Design and study of a high-current 5-cell superconducting rf cavity

The Advanced Photon Source (APS) at Argonne National Laboratory is considering the development of a superconducting linac-based fourth-generation hard X-ray source to meet future scientific needs of the hard X-ray user community. This work specifically focuses on the design of an optimized 5-cell superconducting radio-frequency structure well suited for a high-energy, high-beam-current energy recovery linac. The cavity design parameters are based on the APS storage ring nominal 7 GeV and 100 mA beam operation. A high-current 5-cell cw superconducting cavity operating at 1.4 GHz has been designed. In order to achieve a high current, the accelerating cavity shape has been optimized and large end-cell beam pipes have been adopted. The beam break-up threshold of the cavity has been estimated using the code TDBBU, which predicts a high threshold beam current for a 7 GeV energy recovery linac model. A copper prototype cavity has been fabricated that uses half-cell modules, initially assembled by clamping the cells together.     

Comparison of Spectra Excited in HF and DC Hollow Cathode Discharges

Spectra excited in hollow cathode discharges operating at high frequency (27.2 MHz) and direct currents have been compared. The cathodes made of copper, brass and steel and argon as a carrier gas were used. Line intensity ratios (I_hf/I_dc) for species excited at different pressures have been investigated and discussed.     

Application of movable collimators to the BEPC Ⅱ

BEPC Ⅱ is a double ring e+e-collider with high beam currents and luminosity,so the high beamrelated backgrounds may disturb the detector.In order to have a good quality of data taking,backgrounds should be kept at a level as low as possible.A series of collimators are designed and installed in both the e+and e-rings.Two of the collimators are horizontally movable,each for one ring,about 8 m upstream from the interaction point.Experiments have been done to identify the effectiveness of the movable collimators with different apertures and beam currents.The results show that the movable collimators are very effective and can reduce as much as about 50% of beam-related backgrounds.     

Relatively Moving Systems in “True Transformations Relativity”

In this paper the physical systems consisting of relatively moving subsystems are considered in the true transformations relativity. It is found in a manifestly covariant way that there is a second-order electric field outside stationary current-carrying conductor. It is also found that there are opposite charges on opposite sides of a square loop with current and these charges are invariant charges.     

用电涡流传感器测金属丝杨氏模量

介绍电涡流传感器测距的基本原理和用它测量金属丝杨氏模量的方法,并把实验结果与光杠杆法相比较。     

A Numerical Simulation of the Winter-Time Current System in the China Sea and Adjacent Areas

The monthly mean circulations in the whole Pacific Ocean are investigated numerically by using a barotropic ocean model with finer horizontal resolutions. The current system in the China Sea and its adjacent areas has been well reproduced. Especially, some warm currents moving windward in winter, such as the South China Sea Warm Current (SCSWC), Taiwan Warm Current (TWO, Yellow Sea Warm Current (YSWC) and Tsushima Warm Current (TsWC) are simulated very well. Numerical results of January show that there exists indeed a so-called "Taiwan-Tsushima-Tsugaru Warm Current System" (TTTWCS) which originates from the area off the southeastern Hainan Island and enters the Pacific Ocean mainly through the Tsugaru Strait in January.     

新型柔性储能器件:柔性锂离子电池

柔性锂离子电池是一种新兴的锂离子电池，虽然与锂离子电池的工作原理相同，但使用柔性的集流体，因此展现出柔性，以及可弯折、可伸缩的特性，所以可以成为柔性/可穿戴器件的动力源。介绍了2种实现柔性锂离子电池的途径：一种是开发基于各种导电集流体（包括碳纳米管、石墨烯和碳布）的柔性锂离子电池；另一种是设计和构筑新型结构（包括电缆/电线型、透明型和可伸缩型）的柔性锂离子电池。     

聚苯乙炔的伏安特性

聚苯乙炔的伏安特性周淑琴（中国科学院化学研究所北京１０００８０）关键词聚苯乙炔，伏 安特性，欧姆电导，空间电荷限制电流，高斯分布陷阱能级，陷阱态密度聚苯乙炔（ＰＰＡ）是一种具有π电子的共轭高分子聚合物，它的光电导特性引起了同行的兴趣［１］．目前高分...     

Thermoconvective instability during electrodialysis

A laser interferometry method is proposed for studying the instability of concentration fields during electrodialysis. It is shown that exceeding the limiting diffusion current density first gives rise to alternating oscillations and then to oscillations at the membrane whose ionogenic groups exhibit the lowest catalytic activity towards the water dissociation reaction. Thereafter, the auto-oscillation process extends over the whole solution volume in the compartments, and dissipative chaos is observed with a further increase in the current density. This instability is presumably a consequence of unevenly distributed heat sources, namely, the Joule heat and the heat of dissociation and recombination of water molecules.