Thermal analysis of the CSNS H－ ion source

There are two cooling systems to maintain the thermal stability of the CSNS H^- ion source during its operation： Air-cooling in the source body of the discharging chamber and water-cooling in the flange on which the discharging chamber is installed. The optimal cooling parameters to ensure the operation of the H^- ion source are determined through a thermal analysis. In addition, a transient analysis is also performed to know exactly the transient temperature variation during the whole 40 ms period of the pulsed mode operation of the ion source.     

你知道自己的性格缺陷吗？

一个人的性格决定着其社交方式、学习方式、处事方式等等。我们很多的烦恼表面看都事出有因，其实大部分是自己的性格所致。每个人性格里多少会带点不好的因子，我们必须正视它，然后努力去改变。做做下面的测试，找找你性格中的缺陷吧!     

Parametric resonance and cooling on an atom chip

This paper observes the parametric excitation on atom chip by measuring the trap loss when applying a parametric modulation. By modulating the current in chip wires, it modulates not only the trap frequency but also the trap position. It shows that the strongest resonance occurs when the modulation frequency equals to the trap frequency. The resonance amplitude increases exponentially with modulation depth. Because the Z-trap is an anharmonic trap, there exists energy selective excitation which would cause parametric cooling. We confirm this effect by observing the temperature of atom cloud dropping.     

BEPCⅡ低温控制系统研制

北京正负电子对撞机重大改造工程(BEPCⅡ)首次应用低温超导技术建造低温系统.低温控制系统通过控制前端低温系统的压力、液位、流量和功率等过程变量,分别产生饱和液氦、两相氦和过冷的单相液氦,使用这三种不同形式的氦流来冷却超导设备.低温控制系统采用EPICS+PLC双层架构体系,实现对前端低温超导设备的全自动控制.EPICS主要完成低温系统的过程控制、逻辑控制和PID闭环控制;PLC负责前端关键设备的联锁控制,用于保护低温超导设备的安全.     

Cavity-enhanced laser cooling of solid-state materials in a standing-wave cavity

We propose a new method to cool the yb^3＋-doped ZBLANP glass in a standing-wave cavity. There are two advantages of this cavity-enhanced technique： the pumping power is greatly enhanced and the absorption of the cooling material is greatly increased. We introduce the basic principle of the cavity-enhanced laser cooling and discuss the cooling effect of a solid-state material in a cavity. From the theoretical study, it is found that the laser cooling effect is strongly dependent on the reflectivity of the cavity mirrors, the length of the solid material, the surface scattering of the material, and so on. Some optimal parameters for efficient laser cooling are obtained.     

TEM01模式激光对两能级原子的作用力研究

推导了两能级原子在稳态和小速度一阶微扰近似下的受力矢量方程，并分析表明ＴＥＭ０１模光场以原子的作用力中存在旋涡力，对在大正失谐δ〉〉Ω０〉〉Г和ｚ〈〈ｚ０＝ｋｗ＾２／λ条件下的ＴＥＭ０１模行波和驻波场中原子的受力进行了分析，对行波场，自发辐射对原子运动的影响很大，但在ｒ〈〈λ区域内原子受到横向囚禁力；对驻波场，自发辐射的影响可以忽略，考虑在ｚ方向波长范围内原子的平均受力得到的结论为：在横向，除了有     

HIRFL-CSRm纵向随机冷却-槽形滤波冷却模拟研究

 通过Fokker Planck方程,对拟在HIRFL-CSRm上建造的纵向槽形滤波器（notch filter）的冷却机理进行了研究,得出了冷却原理及冷却时间的表达式,并对影响冷却时间和冷却效果的因素进行了模拟和讨论,模拟结果表明,噪信比越小,冷却时间越短,冷却效果越好;带宽越宽冷却越快。该研究为具体纵向冷却系统的设计和优化提供了依据。     

固体材料反斯托克斯荧光制冷的理论研究及其最新进展

本文首先回顾了反斯托克斯荧光制冷的历史发展,简单讨论了激光制冷的循环过程及其制冷条件;其次,概述了反斯托克斯Raman散射、反斯托克斯荧光制冷的热力学理论和热力学限制,重点介绍了适用于各种制冷材料(如稀土离子掺杂玻璃、半导体和晶体等)反斯托克斯荧光制冷研究的理论模型,并简单讨论了激光制冷实验中各种测量温度变化的实验方法及其基本原理。最后,就反斯托克斯荧光制冷的一种最新应用及其前景进行了简单介绍与展望。