15,114 results on '"*LIQUID helium"'
Search Results
2. Tuning the superconducting dome in granular aluminum thin films.
- Author
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Deshpande, Aniruddha, Pusskeiler, Jan, Prange, Christian, Rogge, Uwe, Dressel, Martin, and Scheffler, Marc
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SUPERCONDUCTING transitions , *THICK films , *ALUMINUM films , *CRITICAL temperature , *LIQUID helium - Abstract
The peculiar superconducting properties of granular aluminum, which consists of nanometer-sized aluminum grains separated by aluminum oxide, are attractive for applications in quantum circuitry, and they are interesting from a fundamental materials physics view. The phase diagram of granular aluminum as a function of normal-state resistivity features a superconducting dome with a maximum critical temperature T c well above the T c = 1.2 K of pure aluminum. Here, we show how the maximum T c of this superconducting dome grows if the substrate temperature during deposition is lowered from 300 K to cooling with liquid nitrogen (150 and 100 K) and liquid helium (25 K). The highest T c that we observe is 3.27 K. These results highlight that granular aluminum is a model system for complex phase diagrams of superconductors and demonstrate its potential in the context of high kinetic inductance applications. This is augmented by our observation of comparably sharp superconducting transitions of high-resistivity samples grown at cryogenic temperatures and by a thickness dependence even for films substantially thicker than the grain size. [ABSTRACT FROM AUTHOR] more...
- Published
- 2025
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3. Stochastic computer experiments of the thermodynamic irreversibility of bulk nanobubbles in supersaturated and weak gas–liquid solutions.
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Al-Awad, Abdulrahman S., Batet, Lluis, Rives, Ronny, and Sedano, Luis
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MOLECULAR dynamics , *COMPUTER simulation , *STOCHASTIC processes , *LIQUID helium , *COMPUTERS - Abstract
Spontaneous gas-bubble nucleation in weak gas–liquid solutions has been a challenging topic in theory, experimentation, and computer simulations. In analogy with recent advances in crystallization and droplet formation studies, the diffusive-shielding stabilization and thermodynamic irreversibility of bulk nanobubble (bNB) mechanisms are revisited and deployed to characterize nucleation processes in a stochastic framework of computer experiments using the large-scale atomic/molecular massively parallel simulator code. Theoretical bases, assumptions, and limitations underlying the irreversibility hypothesis of bNBs, and their computational counterparts, are extensively described and illustrated. In essence, it is established that the irreversibility hypothesis can be numerically investigated by converging the system volume (due to the finiteness of interatomic forces) and the initial dissolved-gas concentration in the solution (due to the single-bNB limitation). Helium nucleation in liquid Pb17Li alloy is selected as a representative case study, where it exhibits typical characteristics of noble-gas/liquid-metal systems. The proposed framework lays down the bases on which the stability of gas-bNBs in weak and supersaturated gas–liquid solutions can be inferred and explained from a novel perspective. In essence, it stochastically marches toward a unique irreversible state along out-of-equilibrium nucleation/growth trajectories. Moreover, it does not attempt to characterize the interface or any interface-related properties, neither theoretically nor computationally. It was concluded that bNBs of a few tens of He-atoms are irreversible when dissolved-He concentrations in the weak gas–liquid solution are at least ∼50 and ∼105 mol m−3 at 600 and 1000 K (and ∼ 80 MPa), respectively, whereas classical molecular dynamics -estimated solubilities are at least two orders of magnitude smaller. [ABSTRACT FROM AUTHOR] more...
- Published
- 2024
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4. An anti-maser for mode cooling of a microwave cavity.
- Author
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Blank, Aharon, Sherman, Alexander, Koren, Boaz, and Zgadzai, Oleg
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SUPERCONDUCTING circuits , *CAVITY resonators , *LIQUID helium , *CONDENSED matter , *LOW temperatures , *PHASES of matter , *MICROWAVES - Abstract
The maser, a microwave (MW) analog of the laser, is a well-established method for generating and amplifying coherent MW irradiation with ultralow noise. This is usually accomplished by creating a state of population inversion between two energy levels separated by MW frequency. Thermodynamically, such a state corresponds to a small but negative temperature. The reverse condition, where only the lower energy level is highly populated, corresponds to a very low positive temperature. In this work, we experimentally demonstrate how to generate such a state in condensed matter at moderate cryogenic temperatures. This state is then used to efficiently remove microwave photons from a cavity, continuously cooling it, well below its ambient temperature. Such an "anti-maser" device could be extremely beneficial for applications that would normally require cooling to millikelvin temperatures to eliminate any MW photons. For instance, superconducting MW quantum circuits (such as qubits and amplifiers) could, with the use of this device, operate efficiently at liquid helium temperatures. [ABSTRACT FROM AUTHOR] more...
- Published
- 2023
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5. Numerical Study on Heat Leakage, Thermal Stratification, and Self-Pressurization Characteristics in Liquid Helium Storage Tanks.
- Author
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Xu, Jing, Liu, Fa'an, Zhang, Jianguo, Li, Chao, Liu, Qinghua, Li, Changjun, Jia, Wenlong, Fu, Shixiong, and Li, Longjiang
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LIQUID helium , *HEAT flux , *NATURAL heat convection , *HEAT transfer , *MASS transfer , *STORAGE tanks - Abstract
During the operation of liquid-phase He-4 (LHe-4) storage tanks, heat leakage changes the thermophysical parameters and phase properties of the LHe-4 in the tanks, resulting in the thermal layering phenomenon. This phenomenon is characterized by the LHe-4 temperature gradient and pressure increase (self-pressurization) phenomena in the tanks. Based on the Layer-by-Layer model, a heat transfer model of a composite adiabatic structure with multilayer insulation and liquid nitrogen screen (LNCS) insulation was established, and the Neumann boundary heat flux of the thermal response model was determined. A numerical simulation model of the thermal response of a liquid helium storage tank was established. The spatial and temporal evolutions of the pressure distribution, natural convection characteristics, thermal stratification characteristics, and self-pressurization characteristics of the LHe-4 tank were investigated. Finally, the self-pressurization thermodynamic model of the LHe-4 storage tank was built based on the isothermal saturation and homogeneous model. It is shown that the predictive performance of the mLee model for the self-boosting characteristics (relative deviation of 14.32%) was significantly improved compared with that of the Lee model (relative deviation of 39.64%). The thermal stratification degree (TSD) of the tank increased with the operation time, with TSDs of 1.023, 1.028, and 1.036 at 1 h, 2 h, and 3 h, which exacerbated the self-pressurization of the tank. The wall surface in contact with the phase interface is a strong evaporation point, so the interfacial mass transfer rate maps show a pattern of high at both ends and low in the middle. [ABSTRACT FROM AUTHOR] more...
- Published
- 2024
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6. An ultra-high vacuum scanning tunneling microscope with pulse tube and Joule–Thomson cooling operating at sub-pm z-noise.
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Eßer, Marcus, Pratzer, Marco, Frömming, Marc, Duffhauß, Jonas, Bhaskar, Priyamvada, Krzyzowski, Michael A., and Morgenstern, Markus
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ULTRAHIGH vacuum , *TUNNELING spectroscopy , *LIQUID helium , *RADIO frequency , *MAGNETIC properties - Abstract
Low-temperature scanning tunneling spectroscopy is a key method to probe electronic and magnetic properties down to the atomic scale, but suffers from extreme vibrational sensitivity. This makes it challenging to employ closed-cycle cooling with its required pulse-type vibrational excitations, albeit this is mandatory to avoid helium losses for counteracting the continuously raising helium prices. Here, we describe a compact ultra-high vacuum scanning tunneling microscope (STM) system with an integrated primary pulse tube cooler (PTC) for closed-cycle operation. It achieves temperatures down to 1.5 K via a secondary Joule–Thomson stage and a z-noise down to 300 fmRMS in the STM junction for the frequency range of 0.1 Hz–5 kHz (feedback loop off). This is better than many STMs cooled by an external supply of liquid helium. The challenge to combine an effective vibrational decoupling from the PTC with sufficient thermal conduction is tackled by using a multipartite approach including the concept of bellows with minimal stiffness to decouple the PTC vibrationally from the STM and an optimized STM design with minimal vibrational transfer to the STM junction. As important benchmarks, we could reduce the voltage noise in the tunnel junction down to 120 μV and supply radio frequency excitations up to 40 GHz with amplitudes up to 10 mV in the junction via a close-by antenna. The development principally enables other secondary cooling stages such that it opens the perspective for a helium conserving operation of STMs across the whole interesting temperature range. [ABSTRACT FROM AUTHOR] more...
- Published
- 2024
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7. Essential improvement of the JT cryocooler working at liquid helium temperature for space: Efficient and lightweight.
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Chen, Zhichao, Liu, Shaoshuai, Sha, Xinquan, Shen, Yunwei, Yin, Wang, Huang, Zheng, Ding, Lei, Jiang, Zhenhua, Gan, Zhihua, and Wu, Yinong
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LIQUID helium , *ELECTROMAGNETIC interference , *CRYOSTATS , *COMPRESSORS , *TEMPERATURE , *REFRIGERATION & refrigerating machinery , *REFRIGERATORS - Abstract
Due to long lifetime, low level vibration and negligible electromagnetic interference, the Joule-Thomson (JT) cryocooler working at liquid helium temperature has been used in space. However, its cooling capacity and thermodynamic efficiency still need to be further improved under a certain mass limit, which is an essential improvement for space-efficient application of the JT cryocooler. Therefore, in this study, optimization design is carried out for a JT cryocooler working at liquid helium temperature. Based on the modification of Stirling cryocooler, pulse tube cryocooler and JT compressor, the developed JT cryocooler can provide a cooling capacity of 0.36 W at 4.18 K while the total input power and the total mass (without cryostat) are 1157 W and 26.8 kg, respectively. Compared with the literature research, it can be found that the developed JT cryocooler is suitable for space applications. [ABSTRACT FROM AUTHOR] more...
- Published
- 2024
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8. In-situ superconductor temperature sensor for cryogenic integrated circuits.
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KÜÇÜKYILMAZ, Emre, TEKCİ, Nazif Orhun, RAZMKHAH, Sasan, and BOZBEY, Ali
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JOSEPHSON junctions , *CRYOELECTRONICS , *MICROCONTROLLERS , *LIQUID helium , *MEASUREMENT errors - Abstract
Cryogenic circuits, such as those based on single flux quantum (SFQ) logic, function at extremely low temperatures. Therefore, the designs target the utilization of liquid helium (LHe) temperatures, maintaining them at 4.2 K. These specialized circuits can be subjected to measurement either within liquid helium (LHe) baths or enclosed within closed-cycle cryocoolers. However, when utilizing LHe in cryocooler systems, inherent weak thermal contact can lead to temperature gradients between the circuit chip and the cold head, where conventional temperature sensors are typically placed. To address this challenge, this study introduces an innovative on-chip temperature sensing approach that capitalizes on the temperature dependence of the Josephson junction's (JJ) critical current (IC). The relationship between JJ's IC and temperature (IC vs. T) is meticulously derived and calibrated within the cryocooler system. Subsequently, this IC vs. T profile is mathematically fitted to a polynomial function and integrated into an embedded microcontroller. This microcontroller facilitates the supply and measurement of bias currents and voltages, effectively establishing an autonomous temperature monitoring system. Implementing this sensor mitigates temperature disparities on the chip's surface compared to the intended target temperature and eradicates measurement errors that might arise due to such discrepancies. [ABSTRACT FROM AUTHOR] more...
- Published
- 2024
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9. A Brilliant Magnetic Refrigerant Operating Near Liquid Helium Temperature: Enhanced Magnetocaloric Effect in Ferromagnetic EuTi0.75Al0.125Zr0.125O3.
- Author
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Xie, Huicai, Jiang, Jiaxin, Tian, Lu, Mo, Zhaojun, Liu, Guodong, Gao, Xinqiang, Shen, Jun, and Liu, Yao
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MAGNETOCALORIC effects ,MAGNETIC transitions ,MAGNETIC fields ,LIQUID helium ,ADIABATIC temperature ,MAGNETIC entropy - Abstract
Rare earth‐based perovskites have become an attractive research interest in the field of cryogenic magnetic refrigerants due to their unique advantages in practical applications. The remarkable magnetocaloric effect (MCE) renders EuTiO3 a potential magnetic refrigerant in the liquid helium temperature range. More impressively, the tunability between antiferromagnetism (AFM) and ferromagnetism (FM) provides the feasibility of tailoring the magnetism and enhancing the magnetocaloric performance. In this study, the magnetism of EuTi0.75Al0.125Zr0.125O3 is investigated in depth through first‐principles calculations and experimental methods. Both theoretical calculations and experimental results reveal that it exhibits significant ferromagnetism due to the AFM‐FM magnetic transition promoted by the co‐substitution of Al and Zr. Lattice expansion and altered electronic interactions are responsible for the FM behavior, which leads to a significant enhancement of the MCE. With the field change of 0−1 T, the peak values of magnetic entropy change (−ΔSM), refrigerating capacity (RC), and adiabatic temperature change (ΔTad) reach 18.9 J kg−1 K−1, 77.7 J kg−1, and 7.4 K, respectively. More surprisingly, the values of maximum magnetic entropy change (−ΔSMmax$ - {{\Delta}}S_{\mathrm{M}}^{{\mathrm{max}}}$) and maximum adiabatic temperature change ΔTadmax${{\Delta}}T_{{\mathrm{ad}}}^{{\mathrm{max}}}$ for EuTi0.75Al0.125Zr0.125O3 reach 11.4 J kg−1 K−1 and 3.7 K under the field change of 0−0.5 T, respectively. The remarkable magnetocaloric performance proves it to be a brilliant magnetic refrigerant operating near liquid helium temperature. [ABSTRACT FROM AUTHOR] more...
- Published
- 2024
- Full Text
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10. Optimal design of coolant jacket for cryogen transfer pipelines.
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Sivasree, Sajikumar Pillai and Nitin, Baby
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LIQUID hydrogen ,CRYOGENIC liquids ,LIQUID helium ,BOILING-points ,PRESSURE drop (Fluid dynamics) ,LIQUID nitrogen - Abstract
Cryogenic liquids such as liquid oxygen and liquid hydrogen are extensively used in many processes and manufacturing industries. In these industries, transferring cryogens via pipelines is a routine phenomenon. As the boiling points and latent heat of cryogens are low, excessive vaporization of these cryogens is innate. Therefore, ensuring that the cryogen reaches the utility in its liquid form is challenging. In the case of liquid hydrogen and liquid helium, the pipelines are jacketed with a high boiling cryogen like nitrogen. The idea is to dump most of the heat into cheap nitrogen to limit the loss of precious hydrogen or helium. From a heat inleak point, maximizing the amount of nitrogen in the jacket is advantageous by choosing large cross‐sectional areas. Also, larger flow cross sections would lower pressure drops and, therefore, lower pumping costs. However, such a choice would add to the mass of the pipeline. An increase in the mass of the pipeline increases the need for better structural support of the pipeline assembly. Therefore, the design of cryogen jackets for limiting heat inleak is a multi‐objective optimization problem. In this work, we model the heat leak into the hydrogen via the nitrogen jacket and the pressure drop of liquid nitrogen, and we find the mass of the pipeline assembly. Then, we optimize the design of nitrogen jackets fitted over hydrogen pipelines. We employ the evolutionary optimization technique, genetic algorithm (GA), to perform this optimization.cryogen; genetic algorithm; heat inleak; liquid hydrogen; optimization. [ABSTRACT FROM AUTHOR] more...
- Published
- 2024
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11. Electron thermalization length in solid para-hydrogen at low-temperature.
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Borghesani, A. F., Carugno, G., Messineo, G., and Pazzini, J.
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ELECTRONS , *LIQUID helium , *LENGTH measurement , *ELECTRON temperature - Abstract
We report the first ever measurements of the thermalization length of low-energy electrons injected into solid para-hydrogen at a temperature T ≈ 2.8 K. The use of the pulsed Townsend photoinjection technique has allowed us to investigate the behavior of quasi-free electrons rather than of massive, slow negative charges, as reported in all previous literature. We have found an average thermalization length ⟨z0⟩ = 26.1 nm, which is three to five times longer than that in liquid helium at the same temperature. [ABSTRACT FROM AUTHOR] more...
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- 2023
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12. Nucleation of helium in pure liquid lithium.
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Álvarez-Galera, Edgar, Martí, Jordi, Mazzanti, Ferran, and Batet, Lluís
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TRITIUM , *LIQUID helium , *LITHIUM , *NEUTRON capture , *NUCLEAR reactions , *LIQUID metals - Abstract
Tritium self-sufficiency in fusion nuclear reactors will be based on the neutron capture by lithium in the so-called breeding blankets of the reactor, a nuclear reaction that will produce helium along with tritium. The low solubility of helium in liquid metals could cause the eventual formation of helium bubbles, which may have a negative impact on the performance of the breeding blanket in a way that has yet to be fully understood. In this work, we provide deep insight into the behavior of lithium and helium mixtures at experimentally operating conditions (800 K and pressures between 1 and 100 bars) using a microscopic model suitable to describe the interactions between helium and lithium at the atomic level, in excellent agreement with available experimental data. The simulations predict the formation of helium bubbles with radii around 10 Å at ambient pressure with surface tension values in the range of 0.6–1.0 N/m. We also report the cohesive energies of helium and the work of formation of the cluster of atoms, as well as a quantitative estimation of the Hildebrand and Kumar cohesion parameters. Our results indicate that the segregation between He and Li atoms is strong, and once a bubble is formed, it never dissociates. [ABSTRACT FROM AUTHOR] more...
- Published
- 2023
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13. Ne, Ar, and Kr oscillators in the molecular cavity of fullerene C60.
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Jafari, Tanzeeha, Shugai, Anna, Nagel, Urmas, Bacanu, George Razvan, Aouane, Mohamed, Jiménez-Ruiz, Monica, Rols, Stéphane, Bloodworth, Sally, Walkey, Mark, Hoffman, Gabriela, Whitby, Richard J., Levitt, Malcolm H., and Rõõm, Toomas more...
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INELASTIC neutron scattering , *KRYPTON , *FULLERENES , *LIQUID helium , *NOBLE gases , *DIPOLE moments , *LOW temperatures - Abstract
We used THz (terahertz) and INS (inelastic neutron scattering) spectroscopies to study the interaction between an endohedral noble gas atom and the C60 molecular cage. The THz absorption spectra of powdered A@C60 samples (A = Ar, Ne, Kr) were measured in the energy range from 0.6 to 75 meV for a series of temperatures between 5 and 300 K. The INS measurements were carried out at liquid helium temperature in the energy transfer range from 0.78 to 54.6 meV. The THz spectra are dominated by one line, between 7 and 12 meV, at low temperatures for three noble gas atoms studied. The line shifts to higher energy and broadens as the temperature is increased. Using a spherical oscillator model, with a temperature-independent parameterized potential function and an atom-displacement-induced dipole moment, we show that the change of the THz spectrum shape with temperature is caused by the anharmonicity of the potential function. We find good agreement between experimentally determined potential energy functions and functions calculated with Lennard-Jones additive pair-wise potentials with parameters taken from the work of Pang and Brisse, J. Chem. Phys. 97, 8562 (1993). [ABSTRACT FROM AUTHOR] more...
- Published
- 2023
- Full Text
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14. Ne, Ar, and Kr oscillators in the molecular cavity of fullerene C60.
- Author
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Jafari, Tanzeeha, Shugai, Anna, Nagel, Urmas, Bacanu, George Razvan, Aouane, Mohamed, Jiménez-Ruiz, Monica, Rols, Stéphane, Bloodworth, Sally, Walkey, Mark, Hoffman, Gabriela, Whitby, Richard J., Levitt, Malcolm H., and Rõõm, Toomas more...
- Subjects
INELASTIC neutron scattering ,KRYPTON ,FULLERENES ,LIQUID helium ,NOBLE gases ,DIPOLE moments ,LOW temperatures - Abstract
We used THz (terahertz) and INS (inelastic neutron scattering) spectroscopies to study the interaction between an endohedral noble gas atom and the C
60 molecular cage. The THz absorption spectra of powdered A@C60 samples (A = Ar, Ne, Kr) were measured in the energy range from 0.6 to 75 meV for a series of temperatures between 5 and 300 K. The INS measurements were carried out at liquid helium temperature in the energy transfer range from 0.78 to 54.6 meV. The THz spectra are dominated by one line, between 7 and 12 meV, at low temperatures for three noble gas atoms studied. The line shifts to higher energy and broadens as the temperature is increased. Using a spherical oscillator model, with a temperature-independent parameterized potential function and an atom-displacement-induced dipole moment, we show that the change of the THz spectrum shape with temperature is caused by the anharmonicity of the potential function. We find good agreement between experimentally determined potential energy functions and functions calculated with Lennard-Jones additive pair-wise potentials with parameters taken from the work of Pang and Brisse, J. Chem. Phys. 97, 8562 (1993). [ABSTRACT FROM AUTHOR] more...- Published
- 2023
- Full Text
- View/download PDF
15. Infrared Transmission Spectra of TiS3: Fundamental Absorption Edge, Phonons, and Excitons.
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Boldyrev, K. N., Mostovshchikova, E. V., Titov, A. N., Pokrovskii, V. Ya., and Gorlova, I. G.
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CRYSTAL whiskers , *OPTICAL polarization , *ABSORPTION coefficients , *LIQUID helium , *SINGLE crystals - Abstract
Transmission spectra of TiS3 single crystal whiskers in the infrared and optical bands have been studied at various light polarizations in the temperature range from room to liquid helium. The absolute absorption coefficients have been determined. Previously unknown phonon modes have been observed in the far infrared region. The study of the temperature dependence of the band gap width has shown that it increases by 50 meV under cooling from 300 to 5 K. The comparison of spectra measured at different polarization directions indicates that the optical gap is anisotropic. A 1.28-eV absorption peak has been detected below ~150 K and has been attributed to the excitation of excitons. [ABSTRACT FROM AUTHOR] more...
- Published
- 2024
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16. A new LHe-free cryostat for the heterodyne SIS receiver for the Leighton Chajnantor Telescope.
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Li, Yao, Cao, Duo, Zhang, Yi, He, Xiaoyong, Liu, Feng, Shi, Wangzhou, and Shu, Chenggang
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SUBMILLIMETER astronomy , *LIQUID helium , *LABOR costs , *THERMAL analysis , *CRYOSTATS - Abstract
The Leighton Chajnantor Telescope (LCT) is an international collaborative program among Caltech, Shanghai Normal University (ShNU), and Universidad de Concepción (UdeC), aiming at the refurbishment and relocation of the Caltech Submillimeter Observatory (CSO) telescope from Mauna Kea, Hawaii, to the Chajnantor Plateau, northern Chile. A suite of excellent-sensitivity heterodyne superconductor–insulator–superconductor (SIS) receivers will be deployed to the telescope as the first set of instrumentations for high-resolution spectral observation. However, the current refrigeration technology for this receiver utilizes liquid helium (LHe), which greatly increases the cost of cooling and labor. To address this problem, a new LHe-free cryostat for the LCT heterodyne SIS receiver has been designed, fabricated, and tested. Mechanical and thermal analyses were performed to ensure that the cryostat meets the requirements of the telescope pointing accuracy and the SIS junction working environment, respectively. The experiment testing results are in good agreement with the calculation and analysis, indicating that the proposed LHe-free cryostat meets the operational requirements of the telescope at the new site. [ABSTRACT FROM AUTHOR] more...
- Published
- 2024
- Full Text
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17. Repeatability of image quality in very low‐field MRI.
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Poojar, Pavan, Oiye, Ivan Etoku, Aggarwal, Kunal, Jimeno, Marina Manso, Vaughan, John Thomas, and Geethanath, Sairam
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SIGNAL generators ,MAGNETIC field effects ,MAGNETIC flux density ,ROOT-mean-squares ,LIQUID helium - Abstract
Background: Very low‐field MR has emerged as a promising complementary device to high‐field MRI scanners, offering several advantages. One of the key benefits is that very low‐field scanners are generally more portable and affordable to purchase and maintain, making them an attractive option for medical facilities looking to reduce costs. Very low‐field MRI systems also have lower RF power deposition, making them safer and less likely to cause tissue heating or other safety concerns. They are also simpler to maintain, as they do not require cooling agents such as liquid helium. However, these portable MR scanners are impacted by temperature, lower magnetic field strength, and inhomogeneity, resulting in images with lower signal‐to‐noise ratio (SNR) and higher geometric distortions. It is essential to investigate and tabulate the variations in these parameters to establish bounds so that subsequent in vivo studies and deployment of these portable systems can be well informed. Purpose: The aim of this work is to investigate the repeatability of image quality metrics such as SNR and geometrical distortion at 0.05 T over 10 days and three sessions per day. Methods: We acquired repeatability data over 10 days with three sessions per day. The measurements included temperature, humidity, transmit frequency, off‐resonance maps, and 3D turbo spin echo (TSE) images of an in vitro phantom. This resulted in a protocol with 11 sequences. We also acquired a 3 T data set for reference. The image quality metrics included computing SNR and eccentricity (to assess geometrical distortion) to investigate the repeatability of 0.05 T image quality. The image reconstruction included drift correction, k‐space filtering, and off‐resonance correction. We computed the experimental parameters' coefficient of variation (CV) and the resulting image quality metrics to assess repeatability. We have explored the impact of electromagnetic interference (EMI) on image quality in very low‐field MRI. The investigation involved varying both the distance and amplitude of the EMI‐producing coil from the signal generator to analyze their effects on image quality. Results: The range of temperature measured during the study was within 1.5 °C. The off‐resonance maps acquired before and after the 3D TSE showed similar hotspots and were changed mainly by a global constant. The SNR measurements were highly repeatable across sessions and over the 10 days, quantified by a CV of 6.7%. The magnetic field inhomogeneity effects quantified by eccentricity showed a CV of 13.7%, but less than 5.1% in two of the three sessions over 10 days. The use of conjugate phase reconstruction mitigated geometrical distortion artifacts. Temperature and humidity did not significantly affect SNR or mean frequency drift within the ranges of these environmental factors investigated. The EMI experiment showed that as the amplitude increased the SNR decreased, and concurrently the root mean square of the background increased with a rise in EMI amplitude or a reduction in distance. Conclusions: We found that humidity and temperature in the range investigated did not impact SNR or frequency. Based on the CV values computed session‐wise and for the overall study, our findings indicate high repeatability for SNR and magnetic field homogeneity. [ABSTRACT FROM AUTHOR] more...
- Published
- 2024
- Full Text
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18. A Study on the Liquid Helium Temperature Tensile Property of Fe-21Cr-15Ni-5Mn-2Mo Austenitic Stainless Steel after Solution Treatment.
- Author
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Zhang, Mengxing, Wang, Changjun, Ma, Dangshen, Liu, Yu, Wang, Weijun, Liang, Jianxiong, Fang, Chao, Chu, Weihan, and Huang, Chuanjun
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HIGH strength steel , *AUSTENITIC stainless steel , *TENSILE strength , *SUPERCONDUCTING coils , *LIQUID helium - Abstract
A novel non-magnetic Fe-21Cr-15Ni-5Mn-2Mo austenitic stainless steel with high strength and plasticity has been developed. The microstructure and liquid helium temperature (4.2 K) tensile properties of the top and bottom samples of large-size forged flat steel after solution treatment at 1090 °C were investigated. The results showed that the average grain size of the bottom sample (48.0 ± 6.7 μm) was smaller than that of the top sample (58.8 ± 15.3 μm), and the MX precipitates and Z phases were distributed in the matrix of the samples. The 4.2 K strengths of the samples at the top and bottom were high, and large amounts of annealing twin boundaries played a certain role in strengthening. After cryogenic tensile testing, large amounts of deformation twins, stacking faults, and dislocations were generated inside the austenite grains of both samples, which helped the material to obtain higher plasticity and strength. The top and bottom samples possessed excellent synergies of strength and plasticity at 4.2 K, and the 4.2 K tensile properties of the top sample were as follows: ultimate tensile strength (UTS) of 1850 MPa, yield strength (YS) of 1363 MPa, and elongation (EL) of 26%. The tested steel is thus believed to meet the requirements of combined excellent strength and plasticity within a deep cryogenic environment, and it would be a promising material candidate for manufacturing superconducting coil cases to serve in new generation fusion engineering. [ABSTRACT FROM AUTHOR] more...
- Published
- 2024
- Full Text
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19. Superconducting Self-Shielded and Zero-Boil-Off Magnetoencephalogram Systems: A Dry Phantom Evaluation.
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Tanaka, Keita, Tsukahara, Akihiko, Miyanaga, Hiroki, Tsunematsu, Shoji, Kato, Takanori, Matsubara, Yuji, and Sakai, Hiromu
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SUPERCONDUCTING quantum interference devices , *MAGNETIC shielding , *LIQUID helium , *MAGNETIC fields , *BIOMAGNETISM - Abstract
Magnetoencephalography (MEG) systems are advanced neuroimaging tools used to measure the magnetic fields produced by neuronal activity in the human brain. However, they require significant amounts of liquid helium to keep the superconducting quantum interference device (SQUID) sensors in a stable superconducting state. Additionally, MEG systems must be installed in a magnetically shielded room to minimize interference from external magnetic fields. We have developed an advanced MEG system that incorporates a superconducting magnetic shield and a zero-boil-off system. This system overcomes the typical limitations of traditional MEG systems, such as the frequent need for liquid helium refills and the spatial constraints imposed by magnetically shielded rooms. To validate the system, we conducted an evaluation using signal source estimation. This involved a phantom with 50 current sources of known location and magnitude under active zero-boil-off conditions. Our evaluations focused on the precision of the magnetic field distribution and the quantification of estimation errors. We achieved a consistent magnetic field distribution that matched the source current, maintaining an estimation error margin within 3.5 mm, regardless of the frequency of the signal source current. These findings affirm the practicality and efficacy of the system. [ABSTRACT FROM AUTHOR] more...
- Published
- 2024
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20. Two-level system loss: Significant not only at millikelvin.
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Shan, W. and Ezaki, S.
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LIQUID helium , *DIELECTRIC loss , *DIELECTRIC materials , *ELECTRIC lines , *AMORPHOUS substances - Abstract
Tow-level system (TLS) loss in amorphous dielectric materials has been intensively studied at millikelvin temperatures due to its impact on superconducting qubit devices and incoherent detectors. However, the significance of TLS loss in superconducting transmission lines at liquid helium temperatures remains unclear. This study investigates TLS loss in amorphous SiO 2 at liquid helium temperatures (about 4 K) within a frequency range of 130–170 GHz, using niobium microstrip and coplanar waveguide resonators. Our results demonstrate notable power and temperature dependence of dielectric loss, with the dielectric loss and quasiparticle loss exchanging dominance at around 4 K. These findings are consistent with TLS models and provide crucial insight for the design of superconducting devices operating at liquid helium temperatures. [ABSTRACT FROM AUTHOR] more...
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- 2024
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21. 基于多物理场耦合分析的超导耦合器失超过程研究.
- Author
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周健荣, 常正则, 刘枭, 黄彤明, 张沛, 李少鹏, and 葛锐
- Subjects
LIQUID helium ,ELECTROMAGNETIC fields ,NIOBIUM ,HEATING control ,LEAD time (Supply chain management) - Abstract
Copyright of Acta Scientiarum Naturalium Universitatis Pekinensis is the property of Editorial Office of Acta Scientiarum Naturalium Universitatis Pekinensis and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.) more...
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- 2024
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22. Numerical Calculation of Electric Field Enhancement in Neutron Traps with Rough Walls Coated with Superfluid Helium.
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Kochev, V. D., Mogilyuk, T. I., Kostenko, S. S., and Grigoriev, P. D.
- Abstract
A film of liquid helium on the surface of material traps for ultracold neutrons protects the neutrons from being absorbed by the trap walls. By using surface roughness and an electrostatic field, it is possible to maintain a helium film of sufficient thickness throughout the height of the trap. The field distribution near the tip of such wall roughness of the trap was calculated, and the effect of this field on holding the helium film was estimated. [ABSTRACT FROM AUTHOR] more...
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- 2024
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23. High Current Measurement of Commercial REBCO Tapes in Liquid Helium: Experimental Challenges and Solutions.
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Masi, Andrea, Freda, Rosa, Formichetti, Andrea, Greco, Alberto, Alimenti, Andrea, Khan, Masood Rauf, and Celentano, Giuseppe
- Subjects
HIGH temperature superconductors ,CRITICAL currents ,FUSION reactors ,LIQUID helium ,CONDUCTORS (Musicians) - Abstract
Recent advances in high-temperature superconductors (HTS) have made them extremely attractive for low-temperature, high-magnetic-field-power applications such as in fusion technology, where the advantages over traditional low-temperature superconductors (LTS) allow for the design of fusion reactors operating in different and more convenient regimes. However, the performance enhancement exhibited by novel conductors poses several challenges for the measurement of their superconducting properties. The high critical currents coupled with the relatively low thermal stability of the conductors and their mechanical fragility render this task a challenge, as the angular anisotropies complicate the experimental setup. In this work, we describe the development of our novel high-current measurement facility, focusing on the solutions introduced regarding critical aspects such as the superconducting leads and the sample holder design. We show how simple but effectively designed solutions can be adopted to combat the complexity of the measurement. The results reported in this work guide the development of a measurement system able to withstand high critical currents (I > 1500 A) at high magnetic fields (µ
0 H > 12 T) by evaluating the angular response of 4 mm wide short samples (L ~ 7.5 cm) in a robust and reproducible manner. [ABSTRACT FROM AUTHOR] more...- Published
- 2024
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24. Excited States of Excitons in MoSe2 and WSe2 Monolayers.
- Author
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Golyshkov, G. M., Brichkin, A. S., Bisti, V. E., and Chernenko, A. V.
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- *
EXCITED states , *TRANSFER matrix , *LIQUID helium , *OPTICAL spectroscopy , *EXCITON theory , *BORON nitride - Abstract
Excitons in MoSe2 and WSe2 monolayers encapsulated with hexagonal boron nitride have been studied using optical reflectance spectroscopy. The ground and excited states of A- and B-excitons have been studied at temperatures from liquid helium to room temperature. The lines of excitons A: , B: and their excited states А: , А: , and В: are clearly observed in the reflectance spectrum. The observed line shapes of the reflection spectrum of transition metal dichalcogenide monolayers depend on the thickness of the hexagonal boron nitride layers used in the structure and are in good agreement with the numerical simulation using the transfer matrix method. For the first time, the values of the reduced masses of B-excitons have been obtained from experimental data and the performed calculations of the exciton binding energy. [ABSTRACT FROM AUTHOR] more...
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- 2024
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25. Quantum computation with electrons trapped on liquid Helium by using the centimeter-wave manipulating techniques.
- Author
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Li, Yufen, He, Suirong, Zhang, Miao, and Wei, Lianfu
- Subjects
- *
QUANTUM computing , *QUANTUM states , *LIQUID helium , *ELECTRON traps , *QUANTUM electrodynamics - Abstract
Surface-state electrons floating on liquid Helium have been served as one of the great potential experimental platforms to implement quantum computation, wherein the qubits are usually encoded by either the lowest two levels of the vertical vibrations (i.e., Hydrogen-like atoms) or the electronic spins. Given the relevant operations require additional techniques, such as the corresponding millimeter-wave or magnetic field manipulations, here we investigate how to implement the scalable quantum computation with a trapped electron array by alternatively using the usual centimeter-wave manipulating techniques. This is because the eigenfrequency of the present qubit, encoded by the two lowest levels of the lateral vibration of the trapped electron, is limited in the centimeter-wave band. We show that, by biasing the electrodes properly and driving the coplanar waveguide transmission line resonator, the electrons can be individually trapped in a series of anharmonic potentials on liquid Helium. Therefore, the well-developed circuit quantum electrodynamics technique for the implementation of superconducting quantum computation can be conveniently utilized here in the present quantum computing platform (proposed firstly in Phys Rev Lett 105:040503, 2010, to implement the fundamental logic gates, typically such as the single-qubit rotations of the individually addressable trapped electrons, the switchable two-qubit manipulations between the electrons trapped in the distant traps, and also the high-fidelity readouts of the target qubits. The feasibility of the proposal is also discussed by numerical simulations. [ABSTRACT FROM AUTHOR] more...
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- 2024
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26. Development of a superconducting undulator cryostat based on the thermosiphon effect.
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Zhang, Xiangzhen, Xu, Miaofu, Chen, Zilin, Yang, Xiangchen, Zhao, Tongxian, Ye, Rui, Yang, Xiaochen, Bian, Xiaojuan, Gao, Yao, Lu, Huihua, Ge, Rui, Zhu, Zian, and Li, Yuhui
- Subjects
- *
SUPERCONDUCTING magnets , *HIGH temperature superconductors , *LIQUID helium , *CRYOSTATS , *HEATING load , *MAGNETS - Abstract
As a specific device for light production, undulators have been researched and developed since the third generation of synchrotron photon sources. Nowadays, superconducting undulators become a research hotspot. However, the cryostat, which is used to create a liquid helium temperature environment, often causes the failure of the superconducting undulator. In this paper, a cryostat for a superconducting undulator is designed and investigated. First, a new refrigeration distribution is proposed that can provide more excess cooling capacity at 4.2 K temperature. For the cooling of the superconducting magnet, a liquid helium circulation loop based on the thermosiphon effect is designed, which has no pump or any other moving parts. Next, based on high-temperature superconducting technology, six binary current leads are used to decrease the heat load. The beam chamber is cooled below 20 K to reduce possible effect on the magnet. In addition, for the tubes that connect the 4.2 K helium tank to the room temperature component, the thermoacoustic oscillation is studied. In the experiment, the superconducting magnet could be cooled and maintained at 4.2 K depending on the thermosiphon loop. No helium was discharged when the magnet went through a quench which generated large heat in a short time. There was no liquid helium consumption and the excess cooling capacity reached 2.2 W. The maximum magnet current is as high as 470 A. This study can provide a valuable reference for the development of superconducting undulator cryostats. [ABSTRACT FROM AUTHOR] more...
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- 2024
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27. A hydrodynamic approach to reproduce multiple spinning vortices in horizontally rotating three-dimensional liquid helium-4.
- Author
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Tsuzuki, Satori
- Subjects
- *
GRAPHICS processing units , *HELIUM atom , *LIQUID helium , *INTERFACIAL tension , *PARTICLE spin - Abstract
This paper reports a three-dimensional (3D) simulation of a rotating liquid helium-4, using a two-fluid model with spin-angular momentum conservation. Our model was derived from the particle approximation of an inviscid fluid with residual viscosity. Despite the fully classical mechanical picture, the resulting system equations were consistent with those of the conventional two-fluid model. We consider bulk liquid helium-4 to be an inviscid fluid, assuming that the viscous fluid component remains at finite temperatures. As the temperature decreased, the amount of the viscous fluid component decreased, ultimately becoming a fully inviscid fluid at absolute zero. Weak compressibility is assumed to express the volume change because some helium atoms do not render fluid owing to Bose–Einstein condensations or change states because of local thermal excitation. One can solve the governing equations for an incompressible fluid using explicit smoothed-particle hydrodynamics, simultaneously reproducing density fluctuations and describing the fluid in a many-particle system. We assume the following fluid–particle duality: a hydrodynamic interfacial tension between the inviscid and viscous components or a local interaction force between two types of fluid particles. The former can be induced in the horizontal direction when non-negligible non-uniformity of the particles occurs during forced two-dimensional rotation, and the latter is non-negligible when the former is negligible. We performed a large-scale simulation of 3D liquid helium forced to rotate horizontally using 32 graphics processing units. Compared with the low-resolution calculation using 2.4 × 106 particles, the high-resolution calculation using 19.6 × 106 particles showed spinning vortices close to those of the theoretical solution. We obtained a promising venue to establish a practical simulation method for bulk liquid helium-4. [ABSTRACT FROM AUTHOR] more...
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- 2024
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28. Low-field nuclear magnetic resonance as an environmentally benign and energy saving analytical tool in organic laboratories
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Gašparová, M. and Tokárová, Z.
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- 2025
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29. Comments on the Origin and Evolution of the Quantum Fluids and Solids Symposia
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Hallock, R. B.
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- 2024
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30. Tailoring the cryogenic magnetism and magnetocaloric effect from Zr substitution in EuTiO3 perovskite.
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Xie, Huicai, Lv, Xiaodong, Mo, Zhaojun, Gong, Jian, Gao, Xinqiang, Li, Zhenxing, Wu, Jinqi, and Shen, Jun
- Subjects
MAGNETOCALORIC effects ,MAGNETIC entropy ,MAGNETIC cooling ,MAGNETISM ,MAGNETIC transitions ,LIQUID helium - Abstract
• Both first-principles calculation and experimental results demonstrate the ferromagnetic feature for EuTi 0.875 Zr 0.125 O 3. • Lattice expansion and changes in electron interaction induced by Zr substitution contribute to the AFM‒FM transition, accompanied by significantly enhanced low-field MCE. • For Δ μ 0 H =0−1 T, the peaks of -Δ S M , RC, and Δ T ad reach 17.9 J kg
−1 K−1 , 87.4 J kg−1 , and 6.1 K, respectively. • Prominent magnetocaloric performance makes EuTi 0.875 Zr 0.125 O 3 compound one of the best magnetic refrigerants in the liquid helium temperature range. Refrigeration in the liquid helium temperature range provides vital technological support for many scientific frontiers and engineering technologies. The considerable magnetocaloric effect (MCE) makes EuTiO 3 a potential candidate for magnetic refrigeration near liquid helium temperature. More interestingly, the magnetic transition from antiferromagnetism to ferromagnetism offers the possibility to tailor the magnetism and improve the MCE of this magnetic system. In this study, the magnetic properties and MCE of EuTi 0.875 Zr 0.125 O 3 were systematically investigated by first-principles calculation and experiments. The substitution of Zr induces a significant lattice expansion and alters the electronic interactions, leading to a dominance of ferromagnetism in the compound. Remarkable low-field MCE performance has been achieved attributed to the enhanced ferromagnetism and low saturation field. Under the field change of 0–1 T, the maximum magnetic entropy change (− Δ S M m a x ) and adiabatic temperature change (Δ T a d m a x ) are 17.9 J kg−1 K−1 and 6.1 K, respectively. It is worth noting that the − Δ S M m a x of EuTi 0.875 Zr 0.125 O 3 reaches 10.3 J kg−1 K−1 for a field change of 0–0.5 T, making it one of the best magnetocaloric materials ever reported operating in the liquid helium temperature range. [Display omitted] [ABSTRACT FROM AUTHOR] more...- Published
- 2024
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31. Mechanical performance and deformation mechanisms of ultrastrong yield strength Fe-Cr-Ni-Mn-N austenitic stainless steel at 4.2 Kelvin.
- Author
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Xin, Jijun, Zhang, Hengcheng, Lyu, Bingkun, Liang, Panyi, Boubeche, Mebrouka, Shen, Fuzhi, Wang, Wei, Sun, Wentao, Shi, Li, Ma, Ruinan, Shan, Xinran, Huang, Chuanjun, and Li, Laifeng
- Subjects
AUSTENITIC stainless steel ,DEFORMATIONS (Mechanics) ,STRAIN hardening ,STAINLESS steel ,STRAIN rate ,LIQUID helium ,DISLOCATIONS in metals - Abstract
• The Fe-Cr-Ni-Mn-N austenitic stainless steel exhibits an exceptional mechanical property at 4.2 K with a high yield strength of 1.5 GPa. • The deformation nanotwinning, HCP ε-martensite transformation, dislocation slip with L -C locks and stacking fault formation which provided a marked contribution to the Fe-Cr-Ni-Mn-N alloy's ultrahigh strain hardening rate and outstanding strength at liquid helium temperature 4.2 K. • The Fe-Cr-Ni-Mn-N austenitic stainless steel displays outstanding cryogenic mechanical properties through a progressive synergy of deformation mechanisms leading to exceptional strength which provides a new insight into the commercialized development of high-performance alloys for cryogenic applications. We report the mechanical performance and microstructural characteristics of a Fe-Cr-Ni-Mn-N alloy at cryogenic temperatures. The exceptionally high yield strength of 1.5 GPa combined with a high strain-hardening rate and no deterioration in ductility at 4.2 K was displayed. The evolution of deformation microstructure was examined using electron backscatter diffraction (EBSD), the transmission Kikuchi diffraction (TKD), high-resolution transmission electron microscopy (HRTEM), and aberration-corrected scanning TEM (STEM). The deformation microstructure mainly consisted of dislocation slip with L -C locks, {111} stacking fault formation, {111} deformation nanotwinning, and FCC → HCP shear transformation at 4.2 K. The occurrence of FCC-HCP shear transformation inside/near {111} twins to form γ-γ tw -ε dual-phase structure induces a dynamic Hall-Petch effect that promotes the strain-hardening rate and enhances the strength-ductility combination. We believe that this alloy displays outstanding damage tolerance through a progressive synergy of deformation mechanisms leading to exceptional strength which provides a new insight into the commercialized development of high-performance alloys for cryogenic applications. [Display omitted] [ABSTRACT FROM AUTHOR] more...
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- 2024
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32. Ohmic contacts on SnO2 produced by hydrogen plasma treatment.
- Author
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Chaplygin, I., Galazka, Z., Herklotz, F., and Lavrov, E. V.
- Subjects
- *
OHMIC contacts , *HYDROGEN plasmas , *LIQUID helium , *TIN oxides , *METALLIC surfaces , *TIN - Abstract
This study introduces a method for creating Ohmic contacts to tin oxide (SnO2) by subjecting the sample surface to hydrogen plasma treatment at moderate temperatures of about 300 °C. This process generates a surface layer of metallic tin droplets, forming suitable electrical contacts. The contacts exhibit remarkable durability and demonstrate Ohmic behavior down to liquid helium temperatures. [ABSTRACT FROM AUTHOR] more...
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- 2024
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33. Unveiling the Stacking Fault-Driven Phase Transition Delaying Cryogenic Fracture in Fe-Co-Cr-Ni-Mo-C-Based Medium-Entropy Alloy.
- Author
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Ding, Hui, Du, Zhenhang, Zhang, Haifeng, Liu, Yu, Zhao, Shiteng, Yang, Yonggang, Wang, Changjun, Lei, Simin, Geng, Ruming, and Wang, Chunxu
- Subjects
- *
PHASE transitions , *MARTENSITIC transformations , *STRAIN hardening , *LIQUID nitrogen , *LIQUID helium , *DISLOCATION density - Abstract
In this work, the tensile deformation mechanisms of the Fe55Co17.5Cr12.5Ni10Mo5−xCx-based medium-entropy alloy at room temperature (R.T.), 77 K, and 4.2 K are studied. The formation of micro-defects and martensitic transformation to delay the cryogenic fracture are observed. The results show that FeCoCrNiMo5−xCx-based alloys exhibit outstanding mechanical properties under cryogenic conditions. Under an R.T. condition, the primary contributing mechanism of strain hardening is twinning-induced plasticity (TWIP), whereas at 77 K and 4.2 K, the activation of martensitic transformation-induced plasticity (TRIP) becomes the main strengthening mechanism during cryogenic tensile deformation. Additionally, the carbide precipitation along with increased dislocation density can significantly improve yield and tensile strength. Furthermore, the marked reduction in stacking fault energy (SFE) at cryogenic temperatures can promote mechanisms such as twinning and martensitic transformations, which are pivotal for enhancing ductility under extreme conditions. The Mo4C1 alloy obtains the optimal strength–ductility combination at cryogenic-to-room temperatures. The tensile strength and elongation of the Mo4C1 alloy are 776 MPa and 50.5% at R.T., 1418 MPa and 71.2% in liquid nitrogen 77 K, 1670 MPa and 80.0% in liquid helium 4.2 K, respectively. [ABSTRACT FROM AUTHOR] more...
- Published
- 2024
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34. Performance Evaluation of the Nanopore Heat Exchanger for Dilution Refrigerator.
- Author
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Temurjonov, Azimjon A., Matsushita, Taku, Hieda, Mitsunori, and Wada, Nobuo
- Subjects
- *
HEAT exchangers , *INTERFACIAL resistance , *LIQUID helium , *NANOPOROUS materials , *DILUTION - Abstract
A crucial problem in the design of heat exchangers (HEx) for dilution refrigerators is thermal boundary resistances between liquid helium and substances rapidly increasing at low temperatures. In addition, thermal resistivity of liquid helium in restricted geometries also increases with decreasing temperature. To solve these problems, recently we developed the nanopore heat exchanger (NHEx), where nanoporous silicate and 75000-nm silver powder are used. Nanoporous materials have huge specific area about of 1000 m 2 /g, which is 3 orders larger compared with conventional fine silver powder sinters widely used for HExs. We have measured the Kapitza resistance of NHEx down to 22 mK and found that it is nearly 10 times smaller than that of conventional sinters with the same size. Use of 75000-nm silver powder instead of 70 nm also allows to reduce thermal resistivity of the liquid. In order to examine performance of the NHEx, quantitative evaluation is performed using numerical simulations. The result shows 3–10 times better performance of NHEx, compared with conventional HExs. [ABSTRACT FROM AUTHOR] more...
- Published
- 2024
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35. Cryogenic Resonant Amplifier for Electron-on-Helium Image Charge Readout.
- Author
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Belianchikov, Mikhail, Kraus, Jakob A., and Konstantinov, Denis
- Subjects
- *
QUANTUM computing , *QUBITS , *ELECTRON transitions , *LIQUID helium , *ELECTRON spin , *CRYOGENICS , *SIGNAL-to-noise ratio - Abstract
An electron-on-helium qubit is a promising physical platform for quantum information technologies. Among all the "blueprints" for the qubit realization, a hybrid Rydberg-spin qubit seems to be a promising one toward quantum computing using electron spins. The main technological challenge on the way to such qubits is a detection of fA range image current induced by a Rydberg transition of a single electron. To address this problem, we aim to use a tank LC-circuit in conjunction with a high-impedance and low power dissipation cryogenic amplifier. Here, we report our progress toward realization of a resonant image current detector with a homemade cryogenic amplifier based on FHX13LG HEMT. We present a detailed characterization of the transistor at room and cryogenic temperatures, as well as details of the amplifier design and performance. At the power dissipation level of amplifier well below 100 μW, the measured voltage and current noise level are 0.6 nV / Hz and below 1.5 fA/ Hz , respectively. Based on the actual image current measurements of the Rydberg transition in a many-electron system on liquid helium, we estimate an SNR = 8 with a measurement bandwidth 1 Hz for the detection of a single-electron transition, providing the noise level at the output is solely determined by the noise of the amplifier. [ABSTRACT FROM AUTHOR] more...
- Published
- 2024
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36. Simulation of Low-Temperature Localized Serrated Deformation of Structural Materials in Liquid Helium Under Different Loading Modes and Potential Energy Accumulation.
- Author
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Vorobyov, E. V. and Anpilogova, T. V.
- Subjects
- *
MECHANICAL behavior of materials , *GRAVITATIONAL potential , *LIQUID helium , *AUSTENITIC steel , *NONLINEAR differential equations - Abstract
Numerical results are presented for the low-temperature serrated deformation process in tension induced by a suspended load of 03Kh20N16AG6 austenitic steel and AMg5 aluminum alloy specimens in liquid helium at 4 K. In practice, large loads at cryogenic temperatures are met with liquefied gas tanks, in particular in hydrogen tanks of launch vehicles. The local one-dimensional multiparametric nonlinear mathematical model of the low-temperature serrated metal deformation process was constructed, with its adequate display and quantitative estimates based on mechanical material properties and loading system characteristics. This effect manifests the local thermomechanical metal deformation instability under adiabatic conditions. The mathematical problem was formulated as a nonlinear differential equation of second order with certain initial and other conditions. It represents the dynamic equilibrium of the specimen-loading device system and describes the process of serrated specimen deformation as the system motion. The model is specified for 03Kh20N16AG6 steel and AMg5 aluminum alloy specimens creep-tested in liquid helium. The numerical experiment demonstrated adequate accuracy with the computational method. The qualitative similarity of the process was revealed for the materials of different classes, with the strain levels achieved differing markedly. Comparative computations established that potential energy of the gravitational field induced a much larger localized deformation of the specimen than potential elastic energy, even in combination with additional factors, viz operation of an electric or hydraulic drive, when the deformation rate is two orders of magnitude higher than the standard one for static metal tests in tension. A very large strain arising and localized under slow loading relaxation inevitably fails before the serrated process is complete. [ABSTRACT FROM AUTHOR] more...
- Published
- 2024
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37. Bose and Fermi Gases in Metric-Affine Gravity and Linear Generalized Uncertainty Principle.
- Author
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Wojnar, Aneta and Gomes, Débora Aguiar
- Subjects
- *
BOSE-Einstein gas , *HEISENBERG uncertainty principle , *QUANTUM gases , *BOSE-Einstein condensation , *ELECTRON gas , *EQUATIONS of state , *GRAVITY - Abstract
Palatini-like theories of gravity have a remarkable connection to models incorporating linear generalized uncertainty principles. Considering this, we delve into the thermodynamics of systems comprising both Bose and Fermi gases. Our analysis encompasses the equations of state for various systems, including general Fermi gases, degenerate Fermi gases, Boltzmann gases, and Bose gases such as phonons and photons, as well as Bose–Einstein condensates and liquid helium. [ABSTRACT FROM AUTHOR] more...
- Published
- 2024
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38. Helium droplet infrared spectroscopy of the butyl radicals.
- Author
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King, Kale E., Franke, Peter R., Pullen, Gregory T., Schaefer III, Henry F., and Douberly, Gary E.
- Subjects
- *
INFRARED spectroscopy , *LIQUID helium , *HELIUM , *RADICALS (Chemistry) , *TEMPERATURE measurements - Abstract
Butyl radicals (n-, s-, i-, and tert-butyl) are formed from the pyrolysis of stable precursors (1-pentyl nitrite, 2-methyl-1-butyl nitrite, isopentyl nitrite, and azo-tert-butane, respectively). The radicals are doped into a beam of liquid helium droplets and probed with infrared action spectroscopy from 2700 to 3125 cm−1, allowing for a low temperature measurement of the CH stretching region. The presence of anharmonic resonance polyads in the 2800–3000 cm−1 region complicates its interpretation. To facilitate spectral assignment, the anharmonic resonances are modeled with two model Hamiltonian approaches that explicitly couple CH stretch fundamentals to HCH bend overtones and combinations: a VPT2+K normal mode model based on coupled-cluster with single, double, and perturbative triple excitations [CCSD(T)] quartic force fields and a semi-empirical local mode model. Both of these computational methods provide generally good agreement with the experimental spectra. [ABSTRACT FROM AUTHOR] more...
- Published
- 2022
- Full Text
- View/download PDF
39. Electrical transport properties of thick and thin Ta-doped SnO2 films.
- Author
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Gao, Zong-Hui, Wang, Zi-Xiao, Hou, Dong-Yu, Liu, Xin-Dian, and Li, Zhi-Qing
- Subjects
- *
ELECTRON-electron interactions , *THERMAL conductivity , *THICK films , *LIQUID helium , *OPTICAL conductivity , *PHONON scattering , *MAGNETRON sputtering - Abstract
Ta-doped SnO 2 films with high conductivity and high optical transparency have been successfully fabricated using the rf-sputtering method, and their electrical transport properties have been investigated. All films reveal degenerate semiconductor (metal) characteristics in electrical transport properties. For the thick films (t ∼ 1 μ m with t being the thickness) deposited in pure argon, the electron–phonon scattering alone cannot explain the temperature-dependent behaviors of resistivity, the interference effect between electron–phonon and electron–impurity scattering should be considered. For t ≲ 36 nm films, both the conductivity and the Hall coefficient show a linear relation with the logarithm of temperature (ln T) from ∼ 100 K down to liquid helium temperature. The ln T behaviors of conductivity and Hall coefficient cannot be explained by the Altshuler-Aronov type electron–electron interaction effect but can be quantitatively interpreted by the electron–electron interaction effects in the presence of granularity. Our results not only provide strong support for the theoretical results on the electron–phonon–impurity interference effect, but also confirm the validity of the theoretical predictions of charge transport in granular metals in a strong coupling regime. [ABSTRACT FROM AUTHOR] more...
- Published
- 2022
- Full Text
- View/download PDF
40. A hermetic on-cryostat helium source for low temperature experiments.
- Author
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Castoria, K. E., Byeon, H., Theis, J., Beysengulov, N. R., Glen, E. O., Koolstra, G., Sammon, M., Lyon, S. A., Pollanen, J., and Rees, D. G.
- Subjects
- *
LOW temperatures , *HELIUM , *LIQUID helium , *SUPERCONDUCTING resonators , *QUANTUM fluids , *IMAGE stabilization - Abstract
We describe a helium source cell for use in cryogenic experiments that is hermetically sealed in situ on the cold plate of a cryostat. The source cell is filled with helium gas at room temperature and, subsequently, sealed using a cold weld crimping tool before the cryostat is closed and cooled down. At low temperatures, the helium condenses and collects in a connected experimental volume, as monitored via the frequency response of a planar superconducting resonator device sensitive to small amounts of liquid helium. This on-cryostat helium source negates the use of a filling tube between the cryogenic volumes and room temperature, thereby preventing unwanted effects such as temperature instabilities that arise from the thermomechanical motion of helium within the system. This helium source can be used in experiments investigating the properties of quantum fluids or to better thermalize quantum devices. [ABSTRACT FROM AUTHOR] more...
- Published
- 2024
- Full Text
- View/download PDF
41. Upgrading and Experiment of the 6T Superconducting Wiggler Magnets' Cryogenic System.
- Author
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Zhang, Haifeng, Li, Weiming, Kuang, Guangli, Ding, Huaikuang, Zhang, Xuehua, Li, Junjie, Jiang, Shili, and Hu, Juli
- Subjects
- *
WIGGLER magnets , *CRYOGENICS , *HIGH temperature superconductors , *LIQUID helium , *SYNCHROTRON radiation , *ENTHALPY , *BIOMASS liquefaction , *SUPERCONDUCTING magnets - Abstract
In 1998, the Hefei National Synchrotron Radiation Laboratory completed the 6 T superconducting Wiggler magnets system. The consumption of liquid helium increases year by year during long operations. In order to upgrade the cryogenic system and remove the use of liquid helium, GM cryocoolers are introduced as the cooling source. The liquid nitrogen and radiation-proof cold screen of the original cryogenic system were removed, and the original copper current leads were replaced with high-temperature superconducting current leads. The total heat load of the cryogenic system is 2.33 W at 4.2 K and 108 W at 60 K. Three GM cryocoolers are selected as the cryogenic source. They can provide 3.75 W at 4.2 K and 210 W at 60 K. In the absence of an external precooling source, the final cryogenic system was successfully cooled and produced liquid helium at a liquefaction rate of 12 L/day at 1.1 bar (inflationary pressure) and had an excess cooling capacity of more than 1.05 W at 4.1 K. [ABSTRACT FROM AUTHOR] more...
- Published
- 2024
- Full Text
- View/download PDF
42. The wall effect in a plane counterflow channel.
- Author
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Galantucci, Luca and Sciacca, Michele
- Subjects
- *
LIQUID helium , *SUPERFLUIDITY , *MARKETING channels , *VELOCITY - Abstract
In this paper, we study the influence of the boundary conditions of the velocity fields in superfluid helium counterflow experiments. To make progress, we perform numerical simulations where we allow a slip velocity of the viscous component at the walls, and observe how this impacts on velocity fields and density profiles of distribution of quantized vortices. We conclude that the presence of a slip velocity at the walls generates a more homogeneous vortex distribution throughout the channel. [ABSTRACT FROM AUTHOR] more...
- Published
- 2024
- Full Text
- View/download PDF
43. Novel correction procedure for compensating thermal contraction errors in the measurement of the magnetic field of superconducting undulator coils in a liquid helium cryostat.
- Author
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Marchetti, Barbara, Baader, Johann, Casalbuoni, Sara, Yakopov, Grigory, and Yakopov, Mikhail
- Subjects
- *
MAGNETIC field measurements , *SUPERCONDUCTING coils , *LIQUID helium , *MEASUREMENT errors , *SYNCHROTRON radiation sources , *SUPERCONDUCTING magnets , *CRYOSTATS - Abstract
Superconducting undulators (SCUs) can offer a much higher on-axis undulator field than state-of-the-art cryogenic permanent-magnet undulators with the same period and vacuum gap. The development of shorter-period and high-field SCUs would allow the free-electron laser and synchrotron radiation source community to reduce both the length of undulators and the dimensions of the accelerator. Magnetic measurements are essential for characterizing the magnetic field quality of undulators for operation in a modern light source. Hall probe scanning is so far the most mature technique for local field characterization of undulators. This article focuses on the systematic error caused by thermal contraction that influences Hall probe measurements carried out in a liquid helium cryostat. A novel procedure, based on the redundant measurement of the magnetic field using multiple Hall probes at known relative distance, is introduced for the correction of such systematic error. [ABSTRACT FROM AUTHOR] more...
- Published
- 2024
- Full Text
- View/download PDF
44. Design and construction of a refrigerator-cooled adiabatic calorimeter for heat capacity measurement in liquid helium temperature region.
- Author
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Luo, Ji-Peng, Yin, Nan, Lu, Jia-Bao, Tan, Zhi-Cheng, and Shi, Quan
- Subjects
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HEAT capacity , *CALORIMETRY , *LIQUID helium , *THERMODYNAMICS , *CALORIMETERS - Abstract
Heat capacity is a fundamental thermodynamic property of a substance. Although heat capacity values and related thermodynamic functions are available for many materials, low-temperature heat capacity measurements, especially for novel materials, can still provide valuable insights for research in physics, chemistry, thermodynamics, and other fields. Reliable low-temperature heat capacity data are typically measured using classical adiabatic calorimeters, which use liquid helium as the refrigerant to provide a cryogenic environment for heat capacity measurements. However, liquid helium is not only expensive but also not easy to obtain, which greatly limits the application of adiabatic calorimetry. In this work, an accurate adiabatic calorimeter equipped with a Gifford–MacMahon refrigerator was designed and constructed for measuring the heat capacity of condensed matter in the temperature range from 4 to 100 K. The Gifford–MacMahon refrigerator was utilized to provide a stable liquid helium-free cryogenic environment. A simple mechanical thermal switch assembly was designed to facilitate switching between the refrigeration mode and the adiabatic measurement mode of the calorimeter. Based on the measurement results of standard reference materials, the optimized repeatability and accuracy of heat capacity measurements were determined to be within 0.8% and 1.5%, respectively. The heat capacity of α-Fe2O3 nanoparticles was also investigated with this device. Furthermore, this adiabatic calorimeter only requires electricity to operate in the liquid helium temperature range, which may significantly advance the research on low-temperature heat capacity based on adiabatic calorimetry. [ABSTRACT FROM AUTHOR] more...
- Published
- 2024
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45. Structural studies of amorphous polymer films: Experiment and calculation.
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Hurova, D. E., Geidarov, V. G., Braude, I. S., Aksenova, N. A., Stepanian, S. G., Adamowicz, L., and Galtsov, N. N.
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POLYMER films , *RADIAL distribution function , *POLYIMIDE films , *LIQUID helium , *DIFFRACTION patterns - Abstract
To analyze X-ray diffraction patterns obtained from polyimide films subjected to external influence (uniaxial tension and exposure at liquid helium temperature), radial distribution function (RDF) curves were constructed and the geometry of the 4,4′-oxydiphenylene-pyromellitimide monomer (PM) was calculated. From the RDF analysis, it follows that uniaxial tension of PM polymer films leads to a change in the geometry of the monomer, and exposure at low temperatures leads to mutual ordering of the polymer chains. [ABSTRACT FROM AUTHOR] more...
- Published
- 2024
- Full Text
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46. Experimental investigation on the vortex-induced vibration response of a lazy-wave flexible riser filled with different fluid media.
- Author
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Zhu, Hongjun, Liu, Wenli, Gao, Yue, Deng, Kairui, and Zhou, Tongming
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RISER pipe , *FLUIDS , *OPTICAL measurements , *BUOYANCY , *LIQUID helium , *LIQUEFIED gases - Abstract
This paper reports the experimental results of the vortex-induced vibration (VIV) of a lazy-wave flexible riser filled with different fluid media, including the water and helium as typical liquid and light gas examples. The lazy-wave configuration was produced by mounting a buoyancy module of approximately triple the riser diameter on the one-third of the riser length measured from the riser base. The VIV tests were carried out in the depth-averaged reduced velocity ( U ¯ r ) range of 9.32–23.19 using the non-intrusive optical measurement with a couple of high-speed cameras. The experimental results indicate that not only the excited mode of in-plane response but also the response amplitude is significantly adjusted when the internal fluid changes, while the excited mode of the out-of-plane response has no obvious modification. Both the water- and helium-filled risers experience the space-varying dominant frequency. However, the helium-filled riser segment possessing a higher dominant frequency is significantly shortened as compared to the water-filled one. When the internal fluid shifts from water to helium, the in-plane mode transition from the first to second becomes incomplete, and the mode transition becomes smoother as U ¯ r grows. It is found that the starting position of the mode transition is related to the dominant mode as well as the response direction. Then, the influenced length of the riser response from the buoyancy module and the affecting length of the riser on the buoyancy module response are quantified in terms of the spatial distribution of the dominant frequency in comparison with the natural frequencies. The in-plane response of the helium-filled riser is more vulnerable to the oscillation of the buoyancy module, and hence, the coupling between the in-plane and out-of-plane responses is weaker than the water-filled riser. When the impact of buoyancy module on the riser response is enhanced, the reverse effect is weakened. [ABSTRACT FROM AUTHOR] more...
- Published
- 2024
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47. 60 T pulsed magnetic field in Bitter magnet made of tungsten and coiled by liquid helium.
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BEDNAREK, Stanisław
- Subjects
LIQUID helium ,MAGNETS ,MAGNETIC fields ,SUPERCONDUCTING magnets ,SUPERCONDUCTING transition temperature ,TUNGSTEN ,ELECTROMAGNETIC induction - Abstract
Copyright of Przegląd Elektrotechniczny is the property of Przeglad Elektrotechniczny and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.) more...
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- 2024
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48. Numerical simulations of proppant transportation in cryogenic fluids: Implications on liquid helium and liquid nitrogen fracturing for subsurface hydrogen storage.
- Author
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Patel, Sanket, Wilson, Isaac, Sreenivasan, Hari, and Krishna, Shanker
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LIQUID nitrogen , *CRYOGENIC fluids , *HYDROGEN storage , *LIQUID helium , *UNDERGROUND storage , *GLOW discharges , *GREENHOUSE gases , *GAS condensate reservoirs - Abstract
The over dependence on fossil fuels for human energy requirements together with the resultant adverse environmental effects in the form of greenhouse gas discharges has redirected our attention towards renewable energy sources. Researchers have identified hydrogen, a non-carbonaceous energy source holding the capacity to substitute fossil fuels, as a viable fuel option that has the potential to be generated utilizing eco-friendly techniques. Studies have identified underground sites that are operational or have the potential to be used for hydrogen storage. Shale formations, characterized by their low permeability, offer promising opportunities for underground hydrogen storage. These formations require stimulation techniques to generate flow channels. Pumping frac-fluid into these formations at high pressure induces fractures in them and the engineered fractures are supported by the proppants injected along with the fluid. Propped fractures form a vital conduit in unconventional gas reservoirs, which are a potential medium for storage of hydrogen. Cryogenic fracturing is an innovative approach that aims to enhance and broaden the capabilities of conventional hydraulic fracturing processes. The transmission and settlement of proppants are influenced by certain critical aspects including their density, size and volume fraction and fluid velocity, which are investigated in this contribution. This study incorporates water and cryogenic fluids like liquid nitrogen (LN 2) and liquid helium (LHe) as fracturing fluids. The primary objective of this effort is to analyze proppant transportation phenomenon and the key influential factors in LN 2 and LHe. The proppant volume fraction contour, equilibrium dune level (EqDL) and dune height (EqDH) data are illustrated in this research for better understanding of proppant migration. It was observed that when the fracturing fluid is given a higher velocity, the proppant grains experience increased drag force, causing them to penetrate deeper into the fracture. The desired range of proppant volume fraction for improved grain transmission was determined as 0.45 to 0.50 and the critical proppant density that significantly affected the EqDL as 187.2839 lb/ft3. • Fracturing of impermeable formations for enhanced underground hydrogen storage. • Eulerian-Granular model for studying the proppant bearing ability of cryogenic fluids. • Desired proppant volume fraction range for improved grain transmission is 0.45–0.50 • Higher fluid velocity enables better proppant transportation. • Cryo-fluids carry low-diameter, low-density proppants deeper into the fractures. [ABSTRACT FROM AUTHOR] more...
- Published
- 2024
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49. Study of power diodes used for MRI applications.
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Nandawadekar, Ajit, Singh, Mukhtiar, and Kar, Soumen
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DIODES , *LIQUID helium , *SUPERCONDUCTING magnets , *MAGNETIC resonance imaging , *LOW temperatures , *MAGNETS , *ELECTRIC current rectifiers - Abstract
Rectifier diodes play a vital role in the operational aspects of a superconducting magnet, and their selection and characterization are crucial for optimal performance and reliability. These diodes are placed within the magnet cryostat, which subjects them to liquid helium (4.2 K) or cryogenic temperatures. The behavior of power diodes can change significantly at cryogenic temperatures. Hence, it is essential to verify their performance before they are installed onto a superconducting magnet system. Thus, a test bench was developed to determine the V–I characteristics of power diodes at low temperatures. In this paper, the two power diodes were tested at 300 K, 77 K, and 4.2 K. The forward voltage was found to increase and have a modest reduction in the on-resistance with the decreases in temperature. The diodes withstood low temperatures down to 4.2 K. The observed forward voltage for the power diode was 4.78 V at 4.2 K, which is around 6–7 times higher than that at room temperature. [ABSTRACT FROM AUTHOR] more...
- Published
- 2024
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50. Environmental modifications of atomic properties: The ground and 1s2p excited states of compressed helium.
- Author
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Pyper, N. C., Naginey, T. C., and Whelan, Colm T.
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HELIUM , *LIQUID helium , *HELIUM atom , *ELECTRON configuration , *ELECTRON scattering , *ATOMIC models - Abstract
Atoms remaining as recognizably distinct constituents of bulk condensed phases can have properties modified from those of the isolated species. Dense helium bubbles at high pressures are a common form of radiation damage degrading the mechanical and electrical properties of host materials. Detailed knowledge is critical for predicting their long term performance. Modifications of the ground and first singlet excited states of confined compressed helium are investigated using an entirely non-empirical theory based on the results of ab initio self-consistent field calculations with corrections for the effects of electron correlation. For finite sized portions representing bulk condensed fcc and bcc phases of helium atoms, Hartree–Fock wavefunctions, energies, and charge distributions were computed as a function of different atomic densities using two models. The first model for the first excited state localizes the excitation on the central atom; in the second model, this is partially delocalized over the closest atomic neighbors. Total energies for the finite size portions are derived by adding the inter-atomic dispersive attractions and a density functional description of the short-range inter-atomic correlation energy. The experimental energy of the first allowed electronic transition increases with density being larger than in an isolated atom. The intra-atomic correlation energy does not contribute to this energy shift. The calculated energy shifts agree well with experiment for both bulk solid and liquid helium. The 2p orbital is increasingly compressed by density enhancement, thus generating the energy shifts. Consequently, calculations of the inelastic electron scattering cross sections are substantially incorrect if the compression of the final 1s2p state is not included. The character of the excitations is examined, and it is argued that these are of Frenkel rather than the Wannier type. [ABSTRACT FROM AUTHOR] more...
- Published
- 2021
- Full Text
- View/download PDF
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