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Many studies on carbon nanotubes (CNTs) have revealed that gas transport behaves differently at the nanoscale compared to the macroscale. While traditional gas transport models do not account for the effect of adsorption, as the adsorbed gases at the macroscopic level are relatively minor and can be ignored, the significant specific surface area of nanochannels leads to a significant increase in the proportion of adsorbed gases. Therefore, the impact of adsorption on gas transport must be taken into consideration. In this study, the diffusion and adsorption behaviors of different gas molecules inside CNTs of different diameters were simulated based on equilibrium molecular dynamic and Grand canonical Monte Carlo methods. The transport diffusion coefficients of gases were calculated using flux correlation functions, and the surface diffusion coefficients of gases were derived by combining with rarefied gas kinetics. The results show that the transport diffusion coefficients of gases in carbon nanotubes are several times or even one order of magnitude higher than those calculated by Knudsen's equation, and the surface diffusion of adsorbed molecules in carbon nanotubes is responsible for the rapid transport, and for the first time, the surface diffusion coefficient of different adsorbed gases in CNTs at different pressures and diameters is derived.

To resolve technical issues associated with the plasma-facing components (PFCs) such as divertor installed in a steady state magnetic fusion DEMO reactor, employing high-temperature metals such as tungsten for the surface component, the use of liquid metals (LMs) such as lithium has been proposed, and evaluated as a possible resolution over the past two or so decades, using plasma confinement devices as well as laboratory-scale experimental facilities. The present work is intended to explore the effect of forced convection in liquid metals on the transport behavior of particles and heat from divertor plasma bombardment. Laboratory-scale experiments have been conducted, using GaInSn and molten lithium as the liquid metal targets to be exposed to steady state plasmas and infrared irradiation. Data clearly indicate that electromagnetically induced convection can enhance particles and heat transport in these liquid metals, proof-of-principle data for convected LM-PFCs.

Different drag laws and turbulence models were compared to evaluate gas distribution and fluid flow velocities in a Rheinstahl–Heraeus (RH) reactor. The discrete phase model was adopted to track injected gas bubbles, and the volume of fluid model was applied to describe a more actual free surface. The prediction accuracy of the numerical model was evaluated by the measured flow velocity in an air-water model and the measured circulation flow rate of molten steel in a real RH system. Results indicate that Morsi’s drag law predicts more accurate local velocity compared with Schiller’s and Harmathy’s laws. The influence of turbulent dispersion on the injected gas bubbles is non-negligible for predicting the gas–liquid flow in a RH reactor. In addition, although the large eddy simulation (LES) approach predicts more actual free surface fluctuation, the realizable k-e model shows better agreement with the measured local velocity in the furnace.

The experiments on deuterium plasma-driven permeation through liquid Ga and Li were conducted in a linear plasma device VEHICLE-1. Deuterium transport parameters such as diffusivity and surface recombination coefficient for Ga and Li were measured from the experiments. By using the measured transport parameters, deuterium dynamic retentions in Ga and Li under steady-state plasma bombardment were evaluated with the DIFFUSE code. It has been found that the deuterium dynamic retention in Ga is ~five orders of magnitude lower than that in Li under present experimental conditions. After exposed to the steady-state deuterium plasma at temperatures from 78 °C to 360 °C, deuterium static retentions in liquid Ga are measured by the thermal desorption spectroscopy. It has been found that the deuterium static retentions in Ga are close to the dynamic retentions when the exposure temperatures are below 250 °C.

The aim of this research is to investigate the effect of average grain size on electrical and electrochemical performances of La0.9Sr0.1Ga0.8Mg0.2O2.85 (LSGM). For this purpose, the glycine-nitrate method is used to synthesize the LSGM electrolytes and subsequently sintered at 1350, 1400, 1450 and 1500 °C in a muffle furnace with temperature holding for 10 h. XRD study reveals that all of the sintered LSGM ceramic electrolytes crystallize to a single phase of orthorhombic perovskite structure without any impurity phases. Results from scanning electron microscopy (SEM) study demonstrate that increasing sintering temperature from 1350 to 1500 °C leads to increase in average grain size from 1.02 to 4.87 μm. Electrochemical AC impedance tests show that the bulk resistance is nearly independent on the average grain size, and the grain boundary resistance changes because of the difference in the average grain size. The LSGM sample sintered at 1500 °C achieves the maximum electrical conductivity 9.19 × 10−2 S cm−1 at 800 °C. The maximum power density of assembled cell with LSGM sintered at 1500 °C as an electrolyte is 0.76 W cm−2 at 800 °C in air atmosphere.

Ag/tungsten disulfide (WS2)–polyvinylpyrrolidone (PVP)/Cu memristors based on monolayer WS2 nanosheets and polyvinylpyrrolidone (PVP) nanocomposites were fabricated, and the influence of PVP content on the switching behaviors was investigated. The results indicate that the WS2–PVP based memristors show write-once read-many times (WORM) memory behavior. Remarkable resistive switching results such as a low operating voltage (VSET 103), good endurance (>100 cycles), and data retention time (>200 s) are obtained. With the increase in the PVP content, the device VSET gradually increases, and the switching ratio first slightly increases and then remarkably decreases. The double logarithm I–V curves verify that the switching mechanism of the devices is the trap-controlled space charge limited current mechanism, which is explained with the energy band diagram.

From the recent experiments on liquid metal plasma-facing components, convection appears to play an important role in maintaining reduced recycling conditions. Either it is natural or forced convection, the transport of the implanted particle is accelerated in the depth direction whereby the surface saturation would be delayed or avoided. Reviewed in this paper are some of the recent studies on particle recycling from liquid metals under plasma bombardment with the emphasis on liquid convection effects. Natural convection has been observed to enhance deuterium plasma-driven permeation. In addition, the effects of J × B forced convection on particle recycling have been extensively studied under steady-state hydrogen, deuterium, helium, and argon plasma bombardment. Also, preliminary fluid dynamics analysis has been conducted to interpret these experimental observations.

The nanofluidic chips with channels of 100-nm depth and 3-μm width were employed as molecular flow standard leak elements for vacuum technology applications in this paper. The nanofluidic chips are fabricated by MEMS technologies while the macro-micro connection is achieved using glass fusion bonding and standard Swagelok® Fitting. It is found that the choice of annealing temperature and holding time is a key issue regarding fusion bonding and the optimal processing parameters are 780 ℃, 5 min. Meanwhile, the sealing reliability of fusion bonding and the fitting connection is evaluated. Experiment shows that the flow conductance of the as-fabricated leak can reach 10−13 m3∙s−1 magnitude for He, N2 and Ar. This standard leak has the advantages of controlled dimensions, reliable connection, and constant flow conductance over a range of 105 Pa.

In this work, a new leak element based on transfer-free single-layer graphene was developed. The single-layer graphene was synthesized on Cu foil and small holes of about 10 μm were drilled on Cu foil to reveal graphene membrane. The conductance of He, N2 and Ar through the graphene leak element was measured based on the difference method. The results imply that various gases exhibit molecular flow regime under pressures ranging from vacuum up to 105 Pa, and the conductance of the transfer-free graphene is about two orders of magnitude smaller than that of the wet-transferred graphene. The difference of conductance may result from the generation of micron-sized cracks and tears on graphene surface during wet-transfer process. The transfer-free single-layer graphene developed in this work is an excellent material for low-permeation leak element.

In this paper, a gas permeability measurement technique in transitional flow regime was proposed, which could characterize the average pore diameter of nanoporous media non-destructively. With high purity argon and carbon dioxide, the conductance of three groups of porous anodic alumina was tested respectively in the transitional flow regime by the dynamic differential pressure attenuation test system, and the average pore diameter of porous anodic alumina was derived. The average pore diameters obtained through the gas permeability measurement technique are consistent with the SEM image analysis results, and the relative error is less than 8%. This method based on the improved transitional flow conductance theory extends the pore-size range of gas permeability measurement technique from micrometer to the nanometer scale, and does not require high pressure or high vacuum. It has the advantages of non-destruction, high-accuracy and large-area-measurement, which brings significant practical application value.

A series of experiments on deuterium plasma interaction with a liquid metal GaInSn alloy have been carried out to investigate the Lorentz-force (J × B-force) convection effects on particle recycling behavior over liquid metals under plasma bombardment. It has been found that deuterium recycling from the liquid is reduced, when forced convection is applied to the liquid. And deuterium recycling is reduced more as the current increases. A finite element analysis method has been applied to simulate the motion of the liquid and the deuterium transport process in the liquid. As a result, the deuterium transport in the liquid is accelerated by the convection.

The application of liquid metals as plasma-facing materials (PFMs) is a potential means to resolve the technical issues associated with power exhausting and particle handing in magnetic fusion devices. Natural convection is a phenomenon commonly present in liquids. To investigate the natural convection effects on deuterium transport behavior in liquid metals, a series of experiments on deuterium Plasma-Driven Permeation (PDP) through a liquid metal GaInSn alloy have been carried out. It has been found that deuterium permeation through the liquid is enhanced by one order of magnitude with natural convection. The motion of the liquid and the deuterium transport process in the liquid have been simulated by a finite element analysis method.

Steady state hydrogen, deuterium and helium plasma interactions with a liquid metal: Ga 67 In 20.5 Sn 12.5 at termperatures between room temperature and ∼250 °C have been investigated with JxB-forced convection, using a laboratory-scale facility: VEHICLE-1. Noticeably reduced recycling has been observed for all these gases, when JxB-forced convection is applied, under respevtive plasma bombardment. Preliminary fluid dynamics modeling has been done to interpret experimental observations. For hydrogenic species, a trend has been found, indicating temperature-dependent retention saturation levels. With thermal desorption spectrometry, the amount of deuterium retention after saturation at ∼250 °C has been evaluated to be of the order of 10 14 D/cm 3 whereas the retention of inert gases is found to be undetectable.

A series of first-of-a-kind laboratory-scale experiments on the JxB -force convected liquid metal divertor concept have been carried out in the temperature range from room temperature to ∼200 °C, employing a eutectic alloy: Ga 67 In 20.5 Sn 12.5 , the melting point of which is 10.5 °C. The electrical current conducted through the alloy is set at about 70A and the magnetic field is set at about 700 G. It has reproducibly been observed that hydrogen as well as helium particle recycling is noticeably reduced under steady state plasma bombardment when the liquid is convected by the JxB force.

The aim of this study is to investigate the effect of grain size on the electrical properties of Ce0.9Gd0.1O1.95-x mol% MgO (GDC-xMgO) and to evaluate them as electrolytes for use in intermediate-temperature solid oxide fuel cells (IT-SOFCs). For this purpose, GDC-xMgO (x = 0–15) electrolytes were synthesized by the glycine-nitrate process and sintered at different temperatures. Impedance spectroscopy measurements revealed that for each composition, the grain-boundary resistivity decreased with decreasing grain size for the samples with grain size of >0.4 μm. Much too small grain sizes (0.2

Grating plays an important role in many fields, so it is of great significance to develop a low-cost and rapid grating fabricating technology. In this paper, the stretching deformation process of PDMS is firstly studied by the COMSOL finite element simulation, and the simulation result proves theoretically that the line-density of PDMS grating could be effectively increased by stretching. Then, we propose a novel method to increase the line-density of grating based on PDMS stretching and PUA replication. The relationship between the elongation and uniform region, line-density increase ratio, groove depth reduction is discussed. The experimental results are consistent with the simulation result. The grating diffraction experiment also proves the effectiveness of the method. Because the process can be repeated several times, the line-density of the grating can be further increased. The experimental results show that the grating period decreased from 10 μm to 5 μm after stretching and replication three times. Besides, the process is also applied to the fabrication of high-density grating. Although this process will lead to some loss of grating contour, compared with other grating fabricating technologies, this process has the advantages of low-cost, simplicity, and rapid fabrication. Therefore, it has good application value in the field of grating fabrication.

A new laboratory-scale linear plasma device, PSIEC (Plasma-Surface Interaction system under Extreme Conditions), has been designed and constructed at Hefei University of Technology, China, to study plasma-material interactions for fusion reactor application. The PSIEC facility can generate continuous plasmas of hydrogen, deuterium, helium, argon and nitrogen. The electron density of these plasmas ranges from the order of magnitude of 1017 to 1018 /m3 and the electron temperature ranges from 1 to 40 eV. The incident ion energy is adjusted by applying a negative bias up to 110 V to the target. The plasma bombarding flux is varied from the order of magnitude of 1021 to 1022 ions/m2/s. Using the PSIEC facility, first plasma exposure experiments have been conducted on bulk tungsten and coatings. The different microstructure of tungsten have been found to lead to different damage effects under helium plasma exposure. Preliminary results allow us to expect nanocrystalline tungsten to be a promising candidate for plasma-facing material, of which the high concentration of intrinsic defects such as grain boundaries and interfaces offers the possibility of improving their irradiation resistance.

Ni 1 − x Cu x bimetallic-based composite anodes were investigated for intermediate temperature solid oxide fuel cells. Ni 1 − x Cu x O and SDC were synthesized using a glycine nitrate process. The electrical conductivity of the Ni 0.90 Cu 0.10 is higher than Ni. The electrical conductivities of the Ni 1 − x Cu x –SDC increase with increasing Cu content (from x = 0 to x = 0.10) and then decrease at x = 0.15. Addition of appropriate amounts of Cu into Ni–SDC to form Ni 1 − x Cu x –SDC anodes obvious improves the electrochemical performance of solid oxide fuel cells.

NdBa 1 − x Co 2 O 5 + δ (NB 1 − x CO, x = 0.00, 0.02, 0.04, and 0.06) have been synthesized and evaluated as cathode materials for use in intermediate temperature solid oxide fuel cells (IT-SOFCs). The effect of Ba deficiency on the structure, thermal and electrochemical properties of NB 1 − x CO is systematically investigated. NB 1 − x CO have a tetragonal layered-perovskite structure. Iodometric titration indicates that the oxygen content decreases and the concentration of oxygen vacancy increases with increasing Ba deficiency. The thermal expansion coefficient decreases with increasing Ba deficiency. An inflection occurs on the slope approximately 300 °C for NBCO that changes to 250 °C for NB 1 − x CO. The results suggest that introduction of Ba deficiency is beneficial for the release of lattice oxygen. Among all of the samples, NB 0.96 CO exhibits the lowest polarization resistances. Increasing oxygen vacancy by introduction Ba deficiency promotes the area conductivity of the oxygen ion transfer at the interface between the cathode and the electrolyte and the area conductivity of the reduction reaction of atom adsorbed oxygen into adsorbed oxygen ion. Our results demonstrate that the NB 0.96 CO electrode is a potential cathode material for IT-SOFCs.

An innovate constant volume flow meter (ICVFM) using AAO leak element was developed, and then applied to measure the pumping speed of dry vacuum pumps. The AAO leak element was calibrated with dynamic differential pressure decay method. The results imply that the conductance of AAO leak is inversely proportional to the square root of the molecular mass, and remains unchanged with pressure varying from vacuum to atmosphere. Then the pumping speed was measured by a simple test system. In the end, the uncertainties of calibrating AAO leak element and measuring pumping speed were considered to confirm the measurement capability. The newly developed flow meter enables flow measurements at pressures ranging from vacuum through atmospheric pressure, which has potential application in the semiconductor industry.

Ba 1−x Sr x Co 0.7 Fe 0.2 Nb 0.1 O 3−δ (x = 0.0–0.2) are proposed as the electrodes for intermediate temperature solid oxide fuel cells (IT-SOFCs) for the first time. The minimum polarization resistance value is achieved at Ba 0.8 Sr 0.2 Co 0.7 Fe 0.2 Nb 0.1 O 3−δ (BSCFN). In this work, BSCFN-xSDC(x = 0–40wt.%) are investigated as the cathodes for IT-SOFCs with SDC electrolyte. The structures of the cathodes are characterized by X-ray diffraction and SEM. The electrode performance of BSCFN-xSDC is measured at various temperatures and oxygen partial pressures. Comparison of the results demonstrate that introduction of ionic conductive SDC to BSCFN-xSDC composite cathode can make the oxygen reduction reaction processes from the three processes into two processes, the charge transfer process and the adsorption and dissociation of gaseous oxygen process. The charge transfer process is the major rate limiting step when oxygen partial pressure is higher than 0.05 atm. The microstructure of BSCFN-30SDC is characterized by more appropriate grain size and more adequate porosity. The area conductivity of adsorption and dissociation of gaseous oxygen process for BSCFN-30SDC is the highest. Comparison of the power density of single cell results demonstrate that BSCFN-xSDC composite cathode has higher power density than BSCFN cathode. BSCFN-30SDC electrode exhibits the highest cathode performance among BSCFN-xSDC composite cathodes.

The composites of Ce 0.85 Sm 0.15 O 1.925 (SDC) and BaCe 0.83 Y 0.17 O 3− δ (BCY) are investigated as electrolytes for solid oxide fuel cells (SOFCs). The electrolyte materials SDC and BCY are synthesized by the glycine–nitrate route and the sol–gel process, respectively. Composite electrolytes are then prepared by mixing SDC and BCY in weight ratios of 9:1 (SB91), 8:2 (SB82), 7:3 (SB73) and 5:5 (SB55). Results from X-ray diffraction (XRD) demonstrate that Sm 3+ can diffuse from SDC to BCY. The SEM results reveal that the average grain size decreases with increasing BCY content. Impedance spectroscopy measurements reveal that the grain boundary resistance can be significantly reduced by adding 10–20 wt.% BCY to SDC. Among all of the samples, SB91 exhibits the lowest total resistance. In the impedance spectra of SB73 and SB55, two grain boundary responses can be identified. Compared with SDC and BCY, the composite electrolytes exhibit lower electrode interfacial polarization resistances. Single cells based on the electrolytes are fabricated using Ni 0.9 Cu 0.1 O x /SDC as anode and LaSr 0.25 Ba 0.75 Co 2 O 5+ δ as cathode. The cell based on SB91 electrolyte exhibits the lowest total resistance under open circuit conditions and the maximum power density of the cell based on SB91 electrolyte reaches 0.495 W cm −2 at 800 °C.

The Torr-Seal gluing method was often used to attach the nanofabricated leak elements to the vacuum system. However, such new leaks are difficult to be applied in ultrahigh vacuum due to the strong outgassing effect of Torr-Seal. To eliminate such issue and achieve enclosed sealing of leak element and CF flange, a new nanofluidic channels type leak assembly has been fabricated based on the glass frit sealing method. Nanofluidic channels with a feature dimension of ∼162 nm were enclosed as a leak element using reactive ion etching and silicon direct bonding processes. The outgassing rate of the leak assembly was analyzed by a residual gas analyzer. The results exhibit that the outgassing rate with the glass paste is 1 order of magnitude lower than that with the Torr-Seal. The flow conductance of helium, nitrogen, and argon was characterized by the difference method. It is found that the measured values are close to the calculated values and the molecular flow is achieved from vacuum to atmosphere pressure.

Hydrogen Plasma-driven Permeation (PDP) experiments through two different liquid metal membranes: lithium and GaInSn have been conducted in the temperature range from 300 to 500 ◦C. A technique employing a mesh sheet to hold a liquid metal for PDP has been utilized for the first time. It has been found that PDP is surface recombination limited for lithium and is diffusion limited for GaInSn. Hydrogen surface recombination coefficients for liquid lithium and hydrogen diffusivity in GaInSn have been obtained respectively.