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By studying the thermal conductivity, specific heat, elastic modulus, and thermal expansion as a function of temperature for Cd3As2, we have unveiled a couple of important thermodynamic features of the low-energy phonons strongly interacting with Dirac electrons. The existence of soft optical phonons, as inferred from the extremely low thermal conductivity, is unambiguously confirmed by low-temperature specific heat revealing significant deviation from Debye’s description. The estimated Debye temperature is small in the range of 100–200 K and varies significantly depending upon the measurement used in its experimental determination. The thermodynamic Grüneisen ratio γ reveals a remarkable reduction below about 100 K, an energy scale that is highly relevant to the Dirac states, towards negative values below about 10 K that are indicative of lattice instability.

CePdAl has been recently recognized as a frustrated antiferromagnetic heavy-fermion compound with a pressure- or field-tuned, extended quantum critical phase at zero temperature. Identifying characteristic signatures of the emerging quantum critical phase, which are expected to be distinct from those near a quantum critical point, remains challenging. In this work, by performing ultrasonic and thermoelectric measurements down to very low temperatures in a 3He–4He dilution refrigerator in the presence of magnetic field, we are able to obtain some crucial thermodynamic and thermal transport features of the quantum critical phase, including a frustration-related elastic softening detected by ultrasound and a Fermi-surface change probed by thermoelectric effect.

In order to diagnose the electron cyclotron resonance (ECR) plasma, a high-efficiency collimation system has been developed at the Institute of Modern Physics, and the bremsstrahlung spectra in the range of 10 keV-300 keV were measured on a third generation superconducting ECR ion source, SECRAL-II, with a CdTe detector. Used as a comparative index of the mean energy of the high energy electron population, the spectral temperature, Ts, is derived through a linear fitting of the spectra in a semi-logarithmic representation. The influences of some main source parameters, such as the neutral gas pressure, extraction voltage, microwave power, and bias disk voltage, on the high energy electrons are systemically investigated.

Ion source development over the last 20 years at the IMP is reviewed. For versatile purposes, several types of ion sources have been involved in the research and development work at the IMP, i.e., the highly charged ECR (Electron Cyclotron Resonance) ion source, intense microwave ion source or the 2.45 GHz intense beam ECR ion source, and laser ion source (LIS). In the development of ECR ion sources, SECRAL (Superconducting ECR ion source with Advanced design in Lanzhou), Lanzhou ECR ion source, and Lanzhou all permanent magnet ECR ion source series have been made, which can cover the operation microwave frequency range of 10–28 GHz. The LIS with an Nd:YAG laser with a maximum output energy of 8 J in 8 ns pulse duration has been developed for very intense short pulse ion beams from solid materials such as C, Ti, Ni, Ag, and so on. Microwave ion sources have been built to produce intense pulsed or direct current beams from several mA to 100 mA for either high intensity accelerators or applications. This paper will give an overview of the high intensity ion source development at the IMP, especially on the recent progress and new results, such as the status of the fourth generation ECR ion source (first fourth generation ECR ion source), the production of recorded highly charged ion beams with SECRAL sources, key technology research studies, and so on.

LAPECR3 (Lanzhou All Permanent magnet Electron cyclotron Resonance ion source No. 3) had been developed as an ion injector of Heavy Ion Medical Machine (HIMM) accelerator facility since 2009. The first HIMM accelerator facility was built in Wuwei city in 2015, and the LAPCER3 ion source has delivered C5+ ion beam to HIMM for more than 1000 days in the past four years. In order to improve the performance of the LAPECR3 ion source for intense carbon beams production, continuous research and development work has been made. The recently developed LAPECR3 ion source together with the new low-energy beam transportation can provide better performance in terms of both beam intensity and quality. This paper will generally review the LAPECR3 ion source operation status for HIMM, and the recent improvement will be presented, especially the stable beams production of C4+ and C5+.

We report a comprehensive investigation of the structural, magnetic, transport and thermodynamic properties of a single crystal PrAlSi, in comparison to its nonmagnetic analogue LaAlSi. PrAlSi exhibits a ferromagnetic transition at $T_C$ = 17.8 K which, however, is followed by two weak phase transitions at lower temperatures. Based on the combined dc and ac magnetic susceptibility measurements, we propose the two reentrant magnetic phases below $T_C$ to be spin glasses or ferromagnetic cluster glasses. When the magnetic glassy states are suppressed by small field, several remarkable features appear. These include a linear, nonsaturating magnetoresistance as a function of field that is reminiscent of a topological or charge-compensated semimetal, and a large anomalous Hall conductivity amounting to $\sim$2000 $\Omega ^{-1}$cm$^{-1}$. Specific-heat measurements indicate a non-Kramers doublet ground state and a relatively low crystal electric field splitting of the Pr$^{3+}$ multiplets of less than 100 K. Shubnikov-de Hass oscillations are absent in LaAlSi, whereas they are clearly observed below about 25 K in PrAlSi, with an unusual temperature dependence of the dominating oscillation frequency $F$. It increases from $F$ = 18 T at 25 K to $F$ = 33 T at 2 K, hinting at an emerging Fermi pocket upon cooling into the ordered phase. These results suggest that PrAlSi is a new system where a small Fermi pocket of likely relativistic fermions is strongly coupled to magnetism. Whether hybridization between $f$ and conduction band is also involved remains an intriguing open problem., Comment: 12 pages, 10 figures

A high intensity highly charged laser ion source has been studied at the Institute of Modern Physics for the last few years. In order to investigate the processes of plasma heating and expansion of laser produced plasma, the charge state and energy distributions of the ions from pure copper, silver, and copper-silver alloy, in which the atom number ratio between copper and silver is 2:3, were measured with a 90° cylindrical electrostatic ion analyzer. It was shown that the yields of highly charged copper ions from the pure copper target are higher compared with those of the alloy target. In contrast, higher yields of highly charged silver ions were obtained from the copper-silver alloy target. Moreover, the ion energy distributions were derived from the time-of-flight spectra for the ions with different ion charge states and compared between the pure metal and alloy targets.

We report the discovery of superconductivity in high-quality single crystals of transition-metal pnictides WP grown by chemical vapor transport method. Bulk superconductivity is observed at ${T}_{\text{c}}\ensuremath{\sim}0.8\phantom{\rule{0.28em}{0ex}}\mathrm{K}$ at ambient pressure by electrical resistivity, ac magnetic susceptibility, and specific-heat measurements. The effects of magnetic field on the superconducting transitions are studied, leading to a large anisotropy parameter around 2 with the in-plane and out-of-plane upper critical fields of ${\ensuremath{\mu}}_{0}{H}_{\text{c}2,\ensuremath{\parallel}}=17.2\phantom{\rule{0.28em}{0ex}}\mathrm{mT}$ and ${\ensuremath{\mu}}_{0}{H}_{\text{c}2,\ensuremath{\perp}}=8.5\phantom{\rule{0.28em}{0ex}}\mathrm{mT}$, respectively. The low value of electron-phonon coupling estimated from the normal-state resistivity and specific-heat measurements suggest that WP is a weak-coupling BCS superconductor. Our finding demonstrates that WP is the first superconductor among $5d$--transition metal pnictides with MnP-type structure at ambient pressure, which will help in the search for new superconductors in transition-metal pnictides.

Needle-like single crystals of CeAu2In4 have been grown from In flux and characterized as a new candidate of quasi-one-dimensional Kondo lattice compound by crystallographic, magnetic, transport, and specific-heat measurements down to very low temperatures. We observe an antiferromagnetic transition at T N ≈ 0.9 K, a highly non-mean-field profile of the corresponding peak in specific heat, and a large Sommerfeld coefficient γ = 369 mJ⋅mol−1⋅K−2. The Kondo temperature T K is estimated to be 1.1 K, being low and comparable to T N. While Fermi liquid behavior is observed deep into the magnetically ordered phase, the Kadowaki–Woods ratio is much reduced relative to the expected value for Ce compounds with Kramers doublet ground state. Markedly, this feature shares striking similarities to that of the prototypical quasi-one-dimensional compounds YbNi4P2 and CeRh6Ge4 with tunable ferromagnetic quantum critical point. Given the shortest Ce–Ce distance along the needle direction, CeAu2In4 appears to be an interesting model system for exploring antiferromagnetic quantum critical behaviors in a quasi-one-dimensional Kondo lattice with enhanced quantum fluctuations.

A high-temperature oven based on the inductive heating technology was developed successfully at the Institute of Modern Physics in 2019. This oven features a durable operation temperature of over 2000 °C inside the tantalum susceptor. By carefully designing the oven structure, the material compatibility issue at high temperature has been successfully solved, which enables the production and routine operation of refractory metal ions with SECRAL-II (Superconducting Electron Cyclotron Resonance ion source with Advanced design in Lanzhou No. 2). To further apply this type of oven to the room temperature ECR ion sources LECR4 and LECR5 (Lanzhou Electron Cyclotron Resonance ion source No. 4 and 5), a mini-inductive heating oven has been fabricated and tested in 2020. By directly evaporating calcium oxide, some high charge state calcium beams have been produced successfully, such as 52 euA of 40Ca16+, 30 euA of 40Ca17+, and 12 euA of 40Ca18+. The detailed design and testing results will be presented and discussed.

We report on the large anisotropic magnetocaloric effect of PrAlSi, a ferromagnetic semimetal of current interest with a probable topologically nontrivial electronic structure. The maximum magnetic entropy change amounts to − Δ S M = 22.6 J / kg K near the Curie temperature T C = 17.8 K under a magnetic field change of μ 0 Δ H = 5 T along the magnetic easy c axis. A highly relevant feature is the small crystalline electric field splitting of the Pr 3 + ( J = 4) multiplet, which appears to be comparable with the effective exchange interaction in the magnetic ordering. This leads to the full saturation moment of the Pr 3 + ion in small fields and an accumulation of magnetic entropy in the vicinity of the magnetic ordering. The weakly first-order nature of the ferromagnetic transition and the subsequent reentrant spin-glass transitions below T C are features further enhancing the magnetocaloric effect. Given the strong magnetic anisotropy, a large rotating magnetocaloric effect becomes achievable in this material.

Unconventional superconductivity frequently emerges as the transition temperature of a magnetic phase, typically antiferromagnetic (AFM), is suppressed continuously toward zero temperature. Here, we report contrary behavior in pressurized $\mathrm{CeRhG}{\mathrm{e}}_{3}$, a noncentrosymmetric heavy-fermion compound. We find that its pressure-tuned AFM transition temperature (${T}_{N}$) appears to avoid a continuous decrease to zero temperature by terminating abruptly above a dome of pressure-induced superconductivity. Near 21.5 GPa, evidence for ${T}_{N}$ suddenly vanishes, the electrical resistance becomes linear in temperature, and the superconducting transition reaches a maximum. Analysis of high-pressure resistance and x-ray-absorption spectroscopy measurements suggest that the anomalous connection between antiferromagnetic and superconducting phases in pressurized $\mathrm{CeRhG}{\mathrm{e}}_{3}$ is associated with proximity to a critical valence instability.

Strange-metal phenomena often develop at the border of antiferromagnetic order in strongly correlated metals. It has been well established that they can originate from the fluctuations anchored by the point of continuous quantum phase transition out of the antiferromagnetic order, i.e., a quantum critical point. What has been unclear is how these phenomena can be associated with a potential new phase of matter at zero temperature. Here we show that magnetic frustration of the 4f-local moments in the distorted Kagome intermetallic compound CePdAl gives rise to such a paramagnetic quantum-critical phase. Moreover, we demonstrate that this phase turns into a Fermi liquid through a Mott-like crossover; in a two-dimensional parameter space of pressure and magnetic field, this crossover is linked to a line of zero-temperature 4f-electron localization-delocalization phase transitions at low and moderate pressures. Our discovery motivates a new design principle for strongly correlated metallic states with unconventional excitations that may underlie the development of such effects as high temperature superconductivity., Comment: 13 pages, 4 figures

We report results of isothermal magnetotransport and susceptibility measurements at elevated magnetic fields B down to very low temperatures T on high-quality single crystals of the frustrated Kondo-lattice system CePdAl. They reveal a B*(T) line within the paramagnetic part of the phase diagram. This line denotes a thermally broadened 'small'-to-'large' Fermi surface crossover which substantially narrows upon cooling. At B_0* = B*(T=0) = (4.6 +/- 0.1) T, this B*(T) line merges with two other crossover lines, viz. Tp(B) below and T_FL(B) above B_0*. Tp characterizes a frustration-dominated spin-liquid state, while T_FL is the Fermi-liquid temperature associated with the lattice Kondo effect. Non-Fermi-liquid phenomena which are commonly observed near a 'Kondo destruction' quantum critical point cannot be resolved in CePdAl. Our observations reveal a rare case where Kondo coupling, frustration and quantum criticality are closely intertwined., Comment: 13 pages, 10 figures

We report the discovery of superconductivity in pressurized CeRhGe3, until now the only remaining non-superconducting member of the isostructural family of non-centrosymmetric heavy-fermion compounds CeTX3 (T = Co, Rh, Ir and X = Si, Ge). Superconductivity appears in CeRhGe3 at a pressure of 19.6 GPa and the transition temperature Tc reaches a maximum value of 1.3 K at 21.5 GPa. This finding provides an opportunity to establish systematic correlations between superconductivity and materials properties within this family. Though ambient-pressure unit-cell volumes and critical pressures for superconductivity vary substantially across the series, all family members reach a maximum Tcmax at a common critical cell volume Vcrit, and Tcmax at Vcrit increases with increasing spin-orbit coupling strength of the d-electrons. These correlations show that substantial Kondo hybridization and spin-orbit coupling favor superconductivity in this family, the latter reflecting the role of broken centro-symmetry.

We report a comprehensive investigation of the electrical, thermal, and thermoelectric transport properties of bulk single-crystalline black phosphorus in wide temperature (2--300 K) and field (0--9 T) ranges. Electrical transport below $T\ensuremath{\approx}$ 250 K is found to be dominated by extrinsic hole-type charge carriers with large mobility exceeding ${10}^{4}$ ${\mathrm{cm}}^{2}$/V s at low temperatures. While thermal transport measurements reveal an enhanced in-plane thermal conductivity maximum $\ensuremath{\kappa}$ = 180 W/m K at $T\ensuremath{\approx}$ 25 K, it appears still to be largely constrained by extrinsic phonon scattering processes, e.g., the electron-phonon process, in addition to intrinsic umklapp scattering. The thermoelectric power and Nernst effect seem to be strongly influenced by ambipolar transport of charge carriers with opposite signs in at least the high-temperature region above 200 K, which diminishes the thermoelectric power factor of this material. Our results provide a timely update to the transport properties of bulk black phosphorus for future fundamental and applied research.

We report on anisotropic electrical, thermal as well as thermoelectric properties of the prototypical Weyl semimetal TaAs. Compared to the normal metallic behavior along a axis, TaAs is more electrically resistive along c axis and exhibits a semiconductor-like resistivity upturn below [Formula: see text] K. In the same temperature range, the thermal conductivity along c axis shows a pronounced maximum of 183 [Formula: see text] characteristic of a crystalline solid, three times higher than that of a axis. The thermoelectric power, while exhibiting enhanced values around room temperature, becomes diminished in a substantial range of temperature ([Formula: see text] K) for both axes. Together with the enhanced Nernst signals, this hints at a dominating ambipolar diffusion as is frequently seen in a compensated semimetal. An in-depth investigation of the anisotropic transport quantities is expected to yield deep insights into the propagating Weyl fermions in TaAs.

Aiming at developing new generation of high-temperature neutron absorbing materials for both structural and functional usages, (B4C + Al2O3)/Al composites were fabricated. Hot forging and extruding were carried out to adjust the microstructures of the composites. The forged samples exhibited a lamellar structure with Al2O3 staying at the grain boundaries. In the extruded sample, most Al2O3 entered into the interior of ultrafine-grains. Different strengthening effects of intergranular and intragranular Al2O3 at room and high temperatures were studied. It was verified that Al2O3 distributed at the grain boundaries was more beneficial to enhance the high-temperature strength by strengthening the grain boundaries and preventing dislocations from annihilating, therefore the forged samples were much stronger than the extruded sample at 375 °C. The sample forged with a height reduction ratio of 8:1 showed an ultimate strength of 342 MPa at room temperature and an ultimate strength of 96 MPa at 375 °C.

The Space Environment Simulation and Research Infrastructure project, which uses various ion beams as irradiated materials in life science research, is being built at the Harbin Institute of Technology. A new room temperature electron cyclotron resonance ion source, the Lanzhou Electron Cyclotron Resonance Ion Source No. 5 (LECR5), has been designed and constructed. It is an intense, highly charged, heavy ion beam injector which generates ion beams from H to Bi, typically ∼50 eμA 209Bi32+. The LECR5 is designed to operate at microwave frequencies in the range of 14.5–18 GHz. The typical magnetic parameters are designed based on those optimized for SECRAL, which operates at 18 GHz. This paper presents the LECR5 ion source, its test bench, and the preliminary beam results.The Space Environment Simulation and Research Infrastructure project, which uses various ion beams as irradiated materials in life science research, is being built at the Harbin Institute of Technology. A new room temperature electron cyclotron resonance ion source, the Lanzhou Electron Cyclotron Resonance Ion Source No. 5 (LECR5), has been designed and constructed. It is an intense, highly charged, heavy ion beam injector which generates ion beams from H to Bi, typically ∼50 eμA 209Bi32+. The LECR5 is designed to operate at microwave frequencies in the range of 14.5–18 GHz. The typical magnetic parameters are designed based on those optimized for SECRAL, which operates at 18 GHz. This paper presents the LECR5 ion source, its test bench, and the preliminary beam results.

An all permanent magnet Electron Cyclotron Resonance ion source-LAPECR1U (Lanzhou All Permanent magnet ECR ion source no.1 Upgraded), has been built at IMP in 2017 to satisfy the requirements of LEAF (Low Energy intense-highly-charged ion Accelerator Facility) for first two years commissioning. LAPECR1U was designed to be operated at 14.5 GHz to produce intense low and medium charge state ion beams. LAPECR1U features a compact structure, small size, and low cost. A cone-shape iron yoke in injection side and an iron plasma electrode in extraction side were used to enhance the axial magnetic field strength. The typical parameters and the preliminary beam results of the source are given in this paper.

According to the requirements of ion beams extracted from an electron cyclotron resonance ion source transverse phase space coupling research and the afterglow beam property effective measurement, a pepper pot type meter called PEMiL (Pepper Pot Emittance Meter in Lanzhou) has been designed, fabricated, and commissioned to obtain the emittance of high intensity highly charged heavy ion beams. The direct current beam emittance measurement results verify the coupling property caused by the semisolenoid field. This paper also describes the scheme of multiple exposure accumulation which was applied to measure the afterglow beam property, and the transverse phase space distribution of the oxygen afterglow beam which was measured for the first time is presented.

The efficiency of the microwave-plasma coupling is a key issue to enhance the performance of electron cyclotron resonance ion sources (ECRISs) in terms of higher ion beam intensity yield. The coupling properties are affected by the microwave coupling scheme, especially for the high frequency (f > 20 GHz) and high power (P > 5 kW) ECR ion sources. Based on the study of 24 GHz SECRAL ion source performances working at different launching systems, a new microwave coupling scheme, called the Vlasov launcher, is proposed, which can not only realize efficient power matching and feeding but also enhance the microwave power distribution on the ECR surface. The first promising results are presented in this article. Then, a prototype dedicated to the next generation ECRIS is described.

The ion beams extracted from an Electron Cyclotron Resonance (ECR) ion source always exist strong transverse coupling effect that is caused by the field of the axis mirror magnets and the extraction solenoid. In order to obtain the four-dimensional (4D) characteristic matrix with coupling elements, a Pepper Pot probe was developed and used to obtain the full 4D transverse phase space distribution of the low energy beam extracted from the ECR ion source at IMP. This paper describes the detailed design and image processing procedure of Pepper Pot probe, especially the analysis results verification compared to another type emittance meter. The first 4D transverse phase space distribution measurement data of oxygen beams from the LECR4 experimental platform are presented and discussed.

A negative oxygen ion source is under development to produce O− and O2− beams used for a secondary ion mass spectrometer at Institute of Modern Physics (IMP), and both filament and radio frequency (RF) schemes are tested. The filament driven ion source, which was initially designed for H− production, has a 10-pole multicusp plasma chamber, two sets of virtual magnetic filters, and a 3-electrode extraction system. The RF scheme, which is improved by changing a RF back plate from the filament ion source, has an external planar spiral RF antenna behind an AlN window. The RF power system consists of a continuous wave (CW) 13.56 MHz/2 kW power supply, a capacitive automatching network and a water-cooled flat RF antenna made from a 6-mm copper tube. Oxygen and carbon dioxide gases are used to produce O− and O2− ion beams, and ion composition is analyzed by using a Wien filter. However, the lifetime of filaments sustains from several minutes to hours before fracture occurred while the RF one can work stably with no maintenance, and the experiment results will be given on O− ion production with two different technologies using our ion source test facility.A negative oxygen ion source is under development to produce O− and O2− beams used for a secondary ion mass spectrometer at Institute of Modern Physics (IMP), and both filament and radio frequency (RF) schemes are tested. The filament driven ion source, which was initially designed for H− production, has a 10-pole multicusp plasma chamber, two sets of virtual magnetic filters, and a 3-electrode extraction system. The RF scheme, which is improved by changing a RF back plate from the filament ion source, has an external planar spiral RF antenna behind an AlN window. The RF power system consists of a continuous wave (CW) 13.56 MHz/2 kW power supply, a capacitive automatching network and a water-cooled flat RF antenna made from a 6-mm copper tube. Oxygen and carbon dioxide gases are used to produce O− and O2− ion beams, and ion composition is analyzed by using a Wien filter. However, the lifetime of filaments sustains from several minutes to hours before fracture occurred while the RF one can work stably with...

From the electrical resistivity and ac susceptibility measurements down to $T$ = 40 mK, a rich temperature-field phase diagram has been constructed for the geometrically frustrated heavy-fermion compound CePdAl. In the limit of zero temperature, the field-induced suppression of the antiferromagnetism in this compound results in a sequence of phase transitions/corssovers, rather than a single critical point, in a critical region of field 3$-$5 T. In the lowest temperature region, a power-law description of the temperature-dependent resistivity yields $A$$\cdot$$T^n$ with $n$$>$2 for all applied fields. However, a quadratic-in-temperature resistivity term can be extracted when assuming an additional electron scattering channel from magnon-like excitations, with $A$ diverging upon approaching the critical regime. Our observations suggest CePdAl to be a new playground for exotic physics arising from the competition between Kondo screening and geometrical frustration., 5 pages, 5 figures

We report on magnetotransport properties of the Kondo semiconducting compound ${\mathrm{CeRu}}_{2}{\mathrm{Al}}_{10}$, focusing on its exotic phase below ${T}_{0}=27$ K. An excess thermal conductivity $\ensuremath{\kappa}$ emerges below ${T}_{0}$ and is gradually suppressed by magnetic field, strikingly resembling those observed in the hidden-order phase of ${\mathrm{URu}}_{2}{\mathrm{Si}}_{2}$. Our analysis indicates that low-energy magnetic excitation is the most likely origin, as was also proposed for ${\mathrm{URu}}_{2}{\mathrm{Si}}_{2}$ recently based on inelastic x-ray scattering measurements of phonon dynamics, despite the largely reduced magnetic moments. Likewise, other transport properties such as resistivity, thermopower, and Nernst effect exhibit distinct features characterizing the very different charge dynamics above and below ${T}_{0}$, sharing similarities to ${\mathrm{URu}}_{2}{\mathrm{Si}}_{2}$, too. Given the exotic nature of the ordered phase in both compounds, whether a unified interpretation to all these observations exists appears to be extremely interesting.

In thin magnetic films with confined geometry, the magnetization can adopt vortex-shaped arrangements. Such vortex states have been studied intensely in ferromagnetic films, but this paper reports the first direct observation of them in an antiferromagnetic system.

Kondo semimetal CeRu4Sn6 is attracting renewed attention due to the theoretically predicted nontrivial topology in its electronic band structure. We report hydrostatic and chemical pressure effects on the transport properties of single- and poly-crystalline samples. The electrical resistivity ρ(T) is gradually enhanced by applying pressure over a wide temperature range from room temperature down to 25 mK. Two thermal activation gaps estimated from high- and low-temperature windows are found to increase with pressure. A flat ρ(T) observed at the lowest temperatures below 300 mK appears to be robust against both pressure and field. This feature as well as the increase of the energy gaps calls for more intensive investigations with respect to electron correlations and band topology.

The Venus Express mission is scheduled for launch in 2005. Among many other instruments, it carries a magnetometer to investigate the Venus plasma environment. Although Venus has no intrinsic magnetic moment, magnetic field measurements are essential in studying the solar wind interaction with Venus. Our current understanding of the solar wind interaction with Venus is mainly from the long lasting Pioneer Venus Orbiter (PVO) observations. In this paper, we briefly describe the magnetic field experiment of the Venus Express mission. We compare Venus Express mission with PVO mission with respect to the solar wind interaction with Venus. Then we discuss what we will achieve with the upcoming Venus Express mission.

Intense heavy ion beams have been produced from IMP 14.5 GHz LECR3 by optimization of the ion source conditions and transmission efficiency. Highly charged stable beams, such as 325 eμA of Ar11+, 95 eμA of Xe26+, 7 eμA of Xe30+, 140 eμA of Fe13+, and 75 eμA of Ni12+, were obtained by 14.5 GHz rf power 800–1000 W. Furthermore, an advanced superconducting ECR ion source named SECRAL is being constructed. SECRAL is designed to operate at rf frequency 18–28 GHz with axial mirror magnetic fields 4.0 T at injection, 2.2 T at extraction, and sextupole field 2.0 T at the plasma chamber wall. The unique feature of this superconducting ECR source is that the sextupole is located outside of the three axial solenoid coils to reduce the interaction force and make the source more compact. Fabrications of the superconducting coils, cryostat, beam transmission line, and other components are almost completed. Tests of the superconducting magnet with sextupole and solenoid coils are under way.

The electrical and structural properties of C60/Sb bilayers were investigated. In situ direct-current conductivity measurement results indicate that the doping of Sb into C60 induces the C60 order-disorder phase transition temperature to increase to ~278 K. According to the results of a transmission electron microscope and atomic force microscope study, such a transition (near 278 K) implies the formation of an interfacial structure of Sb-doped C60. Annealing and the absorption of gases destroy the interfacial structure of Sb-doped C60. A possible mechanism for such a phase transition is discussed.

Recent development of electron cyclotron resonance (ECR) ion sources in China is reviewed. Emphasis is put on high charge state ECR ion sources which have been mainly developed in China by Institute of Modern Physics (IMP). Presently two ECR ion sources built by IMP for highly charged ion beams are put into operation for cyclotrons and atomic physics research. The development of high charge state ECR ion sources at IMP has progressed with a new magnetic field configuration, better condition for extraction of highly charged ions, high mirror magnetic field, large plasma volume, and special techniques to provide extra cold electrons. These techniques greatly enhance the production of highly charged ions from IMP ECR ion sources. So far more than 185 eμA of Ar11+ and 50 eμA of Xe26+ were produced by the IMP ECR ion sources. The metallic ion beam production was tested and the first beam 40Ca11+ was provided to the cyclotrons at IMP. The beam intensity of 40Ca11+ could reach 130 eμA. The next part of this article will report the latest progress of 2.45 GHz ECR ion sources in China. A 2.45 GHz compact permanent magnet proton ion source was designed and constructed by IMP. A new microwave feeding system is applied on this ion source. The ion source is able to deliver 90 mA of mixed ion beam (H1++H2++H3+) after preliminary commissioning. The article also mentions a small 2.45 GHz ECR ion source which was built by Sichuan University and used for industry applications. The dependence of plasma density and electron temperature on radio frequency power, neutral gas pressure, and different microwave windows was measured by a Langmuir probe on this ion source.

Superconducting ECR ion sources can produce intense highly charged ion beams for the application in heavy ion accelerators. Superconducting Electron Resonance ion source with Advanced Design (SECRAL) is one of the few fully superconducting ECR ion sources that has been successfully built and put into routine operation for years. With enormous efforts and RD work, promising results have been achieved with the ion source. Heated by the microwave power from a 7 kW/24 GHz gyrotron microwave generator, very intense highly charged gaseous ion beams have been produced, such as 455 eμA Xe(27+), 236 eμA Xe(30+), and 64 eμA Xe(35+). Since heavy metallic ion beams are being more and more attractive and important for many accelerator projects globally, intensive studies have been made to produce highly charged heavy metal ion beams, such as those from bismuth and uranium. Recently, 420 eμA Bi(30+) and 202 eμA U(33+) have been produced with SECRAL source. This paper will present the latest results with SECRAL, and the operation status will be discussed as well. An introduction of recently started SECRAL II project will also be given in the presentation.

Evaporative cooling technology utilizes phase-change heat transfer mode to achieve the cooling for heating equipment. The heat transfer capacity of evaporative cooling technology is far more than air or water cooling technology. The Electron Cyclotron Resonance ion source magnet is a typical super-high power density magnet, and the evaporative cooling technology is an ideal cooling method for the coils of magnet. In this paper we show the structure and process of coils and the special design of flow channels of coolant for an experiment magnet model. Additionally, the heat transfer circulation is presented and analyzed. By the finite element method, the flow channels are optimized to rationally allocate coolant and to reduce the temperature of coils. For the experiment model, the current density of copper wire of coils is 19 A/mm(2), and the coil-windows current density is larger than 12 A/mm(2). The max temperature of coils is below 80 °C, and the total heat is about 200 kW.

At Institute of Modern Physics, a cw 35 keV, 20 mA intense proton source and the low energy beam transport system (LEBT) have been developed for China Initiative Accelerator Driven Sub-Critical reactor system. In order to ensure high quality transmission of the intense ion beam from the exit of ion source to Radio Frequency Quadrupole (RFQ), a low energy beam transport line is used to focus beam to the RFQ entrance and match the Twiss parameters to the RFQ requirements. The 35 keV, 20 mA ion beam extracted by a three-electrode extraction system from the ion source passes through the LEBT to the RFQ entrance and the root-mean-square emittance is measured to be less than 0.2 π mm mrad. The commissioning results of the ion source and low energy beam transport system are described in this paper. The beam quality and transmission efficiency are also studied.

The magnetothermoelectric characteristics of permalloy film have been investigated by exquisite manipulation of heat flow. Through the angle and field dependence of thermal voltages V-x and V-y, the hybrid of the anomalous and the planar Nernst effect can be observed in the combined longitudinal and transverse temperature field. The interplay between the magnetization of Py and the temperature gradient gives rise to the complex field-dependent behaviors of the anomalous and the planar Nernst effect during magnetization reversal.

A low energy beam transport (LEBT) system has been built for a compact pulsed hadron source (CPHS) at Tsinghua University in China. The LEBT, consisting of two solenoids and three short-drift sections, transports a pulsed proton beam of 60 mA of energy of 50 keV to the entrance of a radio frequency quadrupole (RFQ). Measurement has shown a normalized RMS beam emittance less than 0.2 π mm mrad at the end of the LEBT. Beam simulations were carried out to compare with the measurement and are in good agreement. Based on the successful CPHS LEBT development, a new LEBT for a China ADS projector has been designed. The features of the new design, including a beam chopper and beam simulations of the LEBT are presented and discussed along with CPHS LEBT development in this article.

In order to study the transmission properties of multicharged ion beams between the electron cyclotron resonance (ECR) ion source and the analyzing magnet, a new diagnostic system composed of three Wien filters with three single wires has been built and installed on the IMP ECR source test bench. The single wire is used to measure the beam profile and the beam density distribution, and the Wien filter is used to measure the charge state distribution of ion beam. The single wire and the Wien filter were tested successfully. With this diagnostic system, the beam profile, charge state distributions and beam losses along the transmission line from IMP LECR3 to the analyzing magnet are experimentally studied in different conditions of the ion source.

We have designed and built an emittance scanner which was installed at the beam line of IMP LECR3. The scanner measures the emittance of ECR ion source by the method of electric-sweep, typically named as Electric-Sweep Scanner (ESS). The horizontal and vertical emittances were both measured by two ESSs at the beam line of IMP LECR3. Some preliminary results were obtained. The detailed results and discussions will be presented.

Many experiments have been made to produce metallic ion beams since 1998 at IMP (Institute of Modern Physics). We have designed a small oven that can reach a temperature of more than 1300 °C using 110 W electric power. Typical ion beam currents of 70 eμA of Ca12+, 60 eμA of Mg8+, 25 eμA of Pb27+ have been provided to the IMP cyclotron operation by the LECR2 (LanZhou ECR No. 2). We have also obtained some good results by the metallic ions from volatile compounds method on LECR3 (LanZhou ECR No. 3).

SECRAL (superconducting ECR ion source with advanced design in Lanzhou) ion source has been in routine operation for Heavy Ion Research Facility in Lanzhou (HIRFL) accelerator complex since May 2007. To further enhance the SECRAL performance in order to satisfy the increasing demand for intensive highly charged ion beams, 3-5 kW high power 24 GHz single frequency and 24 GHz +18 GHz double frequency with an aluminum plasma chamber were tested, and some exciting results were produced with quite a few new record highly charged ion beam intensities, such as (129)Xe(35+) of 64 eμA, (129)Xe(42+) of 3 eμA, (209)Bi(41+) of 50 eμA, (209)Bi(50+) of 4.3 eμA and (209)Bi(54+) of 0.2 eμA. In most cases SECRAL is operated at 18 GHz to deliver highly charged heavy ion beams for the HIRFL accelerator, only for those very high charge states and very heavy ion beams such as (209)Bi(36+) and (209)Bi(41+), SECRAL has been operated at 24 GHz. The total operation beam time provided by SECRAL up to July 2011 has exceeded 7720 hours. In this paper, the latest performance, development, and operation status of SECRAL ion source are presented. The latest results and reliable long-term operation for the HIRFL accelerator have demonstrated that SECRAL performance for production of highly charged heavy ion beams remains improving at higher RF power with optimized tuning.

A laser (Nd:YAG laser, 3 J, 1064 nm, 8-10 ns) ion source has been built and under development at IMP to provide pulsed high-charge-state heavy ion beams to a radio frequency quadrupole (RFQ) for upgrading the IMP accelerators with a new low-energy beam injector. The laser ion source currently operates in a direct plasma injection scheme to inject the high charge state ions produced from a solid target into the RFQ. The maximum power density on the target was about 8.4 × 10(12) W∕cm(2). The preliminary experimental results will be presented and discussed in this paper.

CoO/Ag/Fe/Ag(001) films were grown epitaxially and studied using magneto-optic Kerr effect and x-ray magnetic circular dichroism (XMCD). Instead of exponential decay as reported in previous works, we find that both the exchange bias and the coercivity in the epitaxially grown films exhibit a nonmonotonous behavior with the Ag spacer layer thickness. By purposely increasing the film roughness, the nonmonotonous interlayer coupling evolves into a monotonic decrease by increasing the Ag thickness. Furthermore, we show that the interlayer coupling peak diminishes or shifts its peak position by inserting a Cr layer between CoO and Ag.

Electron cyclotron resonance (ECR) ion sources are used for cyclotron complex and atomic physics research at the Institute of Modern Physics (IMP). Intense beams of highly charged gaseous and metallic ions could be produced by the IMP 14.5 GHz ECR ion source (LECR2-Lanzhou Electron Cyclotron Resonance Ion Source No. 2). A particular emphasis has been put on the production of metallic ion beams recently. Metallic ion beams of Mg, Ca, Fe, Ni, Cu, Zn, and Pb were tested at the IMP 14.5 GHz ECR ion source (LECR2) to improve beam intensities and long-term stability. A new ECR ion source (Lanzhou Electron Cyclotron Resonance Ion Source No. 3), an upgraded version of the IMP 14.5 GHz ECR (LECR2) but with double-frequency wave heating (10 GHz+14.5 GHz), is under commissioning. The preliminary results of this new source will be presented. To satisfy the requirements of the heavy ion cooling storage ring that is under construction at IMP, a fully superconducting ECR ion source (Lanzhou Electron Cyclotron Resonance ...

CoO/Fe/Ag(001) films were grown epitaxially and studied by X-ray Magnetic Circular Dichroism (XMCD) and X-ray Magnetic Linear Dichroism (XMLD). After field cooling along the Fe[100] axis to 80 K, exchange bias, uniaxial anisotropy, and 4-fold anisotropy of the films were determined by hysteresis loop and XMCD measurements by rotating the Fe magnetization within the film plane. The CoO frozen spins were determined by XMLD measurement as a function of CoO thickness. We find that among the exchange bias, uniaxial anisotropy, and 4-fold anisotropy, only the uniaxial magnetic anisotropy follows thickness dependence of the CoO frozen spins.

Fe/NiO/MgO/Ag(001) films were grown epitaxially, and the Fe and NiO spin orientations were determined using x-ray magnetic dichroism. We find that the NiO spins are aligned perpendicularly to the in-plane Fe spins. Analyzing both the in-plane and out-of-plane spin components of the NiO layer, we demonstrate unambiguously that the antiferromagnetic NiO spins undergo a continuous spin reorientation transition from the in-plane to out-of-plane directions with increasing of the MgO thickness.

Co thin films were epitaxially grown on Mo(110) and investigated by spin-polarized low-energy electron microscopy. We find that the spin asymmetry of the electron reflectivity from the Co film alternates its sign as a function of both the electron energy and the Co film thickness as a result of spin-polarized quantum well states in the Co film. By measuring spin-dependent quantum well states, we are able to resolve the spin-split energy dispersions of the Co film precisely. The determined spin-resolved energy bands are further tested by fitting the quantum well states using the phase accumulation model, and the result shows an excellent agreement between the fitting and the experimental data.

Tunneling giant magnetoresistance (MR) of the Fe–Al2O3 nanogranular films has been observed over a wide range of Fe volume fraction x and it took a maximum of 4.4% at room temperature for the film with x=0.45 at H=10 kOe. Furthermore, the field dependence of MR of the samples is well described by the form proportional to the square of the magnetization. Moreover, an estimate of the magnetic anisotropy energy density Ku increases with the decrease of x, yielding a value 2 orders of magnitude greater than the value for bulk Fe when x=0.23. The Bloch’s law, MS(T)=MS0(1−BTb), can also hold for all the samples but with nonbulk parameters dependent on the Fe volume fraction. These results reveal a percolation effect on the magnetic properties, as well as the conductance, in such nanogranular films.