Electron Cooling with and Ultracold Electron Beam and Related Applications

电子冷却和超冷电子束及相关应用

基本信息

批准号：
06402005
负责人：
TANABE Tetsumi
金额：
$ 22.66万
依托单位：
University of Tokyo
依托单位国家：
日本
项目类别：
Grant-in-Aid for General Scientific Research (A)
财政年份：
1994
资助国家：
日本
起止时间：
1994 至 1995
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-06402005/
关键词：
Accelerator Electron cooling Atomic phisics Atomic collisions Dissociative Recombination

项目摘要

Electron cooling is now becoming a very important method in atomic physics research as well as accelerator technology. The cooling time and the final accuracy in experiments are determined by the electron temperature which is limited by the cathode temperature at around 1000 ﾟC.If one can further reduce the electron temperature, more efficient cooling will be attained and the electron and ion beam quality will be improved. So far, the whole electron system had been immersed in a uniform solenoid field and the electron beam size was unchaged throughout the beam line. However, electron temperature can be reduced to a level less than the cathode temperature by expanding the electron beam adiabatically in a gradually decreasing solenoid field. Based on this principle, we modified the existing electron system to such adiabatic expansion type. We have chosen an expansion factor of 12.7 in the cross sectional area of the electron beam which was aimed at the maximum resolution. This expansion … More factor is the biggest in the existing electron coolers in the world. In the fiscal 1994, we completed the entire system after the deliberate disign, construction and installation in the storage ring.As the research competition in this area is furious, we started atomic physics experiments immediately after the completion of the device in the late 1994. Consequently, at the first experiment, we have discovered a fine structure in the dissociate recombination spectrum of the molecular ion HD^+. These data nicely compared with the theoretical predictions based on a multi-channel quantum defect theory. This is the first time for the good agreements between theory and experiment in dissociative recombination process. The results were published in the Physical Review Letters which is the most famous journal in physics and is well known for its highly rapid communication. Furthermore, strong isotope effects have been found in the dissociative recombinations of ^4HeH^+, ^3HeH^+, ^4HeD^+ and ^3HeD^+ with the ultracold electron beam. These results have been appreciated by domestic and foreign atomic physicists and were presented at the conferences in Israel, Canada and Japan. Now we are also designing a superconducting electron cooler aiming at ultrahigh accuracy. Less

电子冷却现在已经成为原子物理研究和加速器技术中非常重要的方法，实验中的冷却时间和最终精度取决于电子温度，电子温度受到1000℃左右的阴极温度的限制。进一步降低电子温度，获得更多的冷却，提高电子和离子束质量，到目前为止，整个电子系统都沉浸在均匀的电磁场中，有效电子束尺寸没有改变。然而，通过在逐渐减小的螺线管磁场中绝热膨胀电子束，可以将电子温度降低到低于阴极温度的水平。基于这一原理，我们将现有的电子系统修改为这种绝热膨胀类型。我们选择电子束横截面积的扩展系数为 12.7，以实现最大分辨率。这一扩展系数是 1994 财年世界上现有电子冷却器中最大的。经过精心设计、建造并安装在储存环中，完成了整个系统。由于这方面的研究竞争非常激烈，我们在1994年底装置完成后立即开始了原子物理实验。经过检验，在第一次实验中，我们在分子离子 HD^+ 的解离重组谱中发现了精细结构，这些数据与基于多通道量子缺陷理论的理论预测进行了很好的比较，这是理论与理论之间的第一次良好一致性。实验在研究结果发表在物理学界最著名的期刊《物理评论快报》上，该杂志以其高度快速的通讯而闻名。此外，在^4HeH^+、^的解离重组中还发现了强同位素效应。超冷电子束3HeH^+、^4HeD^+和^3HeD^+这些成果得到了国内外原子物理学家的赞赏，并在国际原子能科学会议上发表。现在我们还在以色列、加拿大和日本设计了一种旨在超高精度的超导电子冷却器。