Development of a new ion-guide with use of magnetic field

利用磁场开发新型离子导向器

基本信息

批准号：
10440069
负责人：
KATAYAMA Ichiro
金额：
$ 3.33万
依托单位：
The University of Tokyo
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (B)
财政年份：
1998
资助国家：
日本
起止时间：
1998 至 1999
项目状态：
已结题

项目摘要

The ion-guide is a novel technique which has been used for nuclear spectroscopy combined with an on-line isotope separator. The principle of the technique is that reaction products recoiling out of the target are stopped and thermalized in a He gas cell while keeping a singly charged state, the ions are carried by gas flow to vacuum, and then accelerated and mass separated by a separator. The advantages of the ion-guide are chemical-property independence and fast separation. There are, however, major drawbacks, i.e., 1) limited yield, 2) poor beam quality, 3) "plasma effect" (presence of primary beam in the cell traps ions). For the point 2), we have developed a cooling device, SPIG (RF sextupole ion beam guide), which has become a standard technique.The aim of the present work is at the points 1) and 3). The origin of the point 1) is in the size of gas cell, which is about 1cm in thickness, and corresponding stopping capability of 10 keV/u. Since the transport is carried only by the g … More as flow, it is hard to increase the size. We have proposed to apply an electric field of a superposition of DC and RF into the cell (RF ion-guide) where ions are totally under control of the field. It allows to use a large cell, e.g., 2 m in length which corresponds to a stopping capability of 5 MeV/u, since the DC electric field keeps fast extraction and the RF electric field protects from diffusion loss to the wall. This large stopping capability also effective to the point 3). The RF ion-guide can be coupled with a projectile fragment separator where the primary beams do not irradiate the gas cell.The present work showed effective transport of ions in a large He gas cell by the RF ion-guide technique. We have also fabricated a funnel structure of RF electrodes with very fine pitch, as fine as 0.3 mm, which allows to use a relatively high pressure of 150 Torr. Though the use of a magnetic field was not tested in the present work, we are certain that it will effective for further increase of effective stopping capability of the cell. Less

离子指导是一种新型技术，已用于核谱与在线同位素分离器结合使用。该技术的原理是，从目标中退出的反应产物被停止并在HE燃气电池中进行热效，同时保持单一充电状态，离子是通过气体流动到真空的，然后加速并由分离器分离的。离子指南的优势是化学质体独立性和快速分离。但是，有主要缺点，即1）有限的产率，2）光束质量差，3）“等离子体效应”（细胞陷阱离子中的原代束存在）。对于点2），我们开发了一个冷却装置，即SPIG（RF Sextupole Ion Beam指南），它已成为标准技术。当前工作的目的是点1）和3）。点1）的起源为燃气电池的大小，厚度约为1厘米，相应的停止功能为10 keV/u。由于运输仅由G携带，而更多的是流动，因此很难增加尺寸。我们已经提议将DC和RF叠加的电场应用于细胞（RF离子指示），其中离子完全控制了该场。它允许使用一个大单元，例如长度为2 m，这对应于5 MeV/u的停止功能，因为直流电场可快速提取，并且RF电场可保护壁的扩散损失。这种大型停止功能也可对点3有效。 RF离子指南可以与弹丸片段分离器结合，在该分离器中，主要梁未照射气电池。目前的工作显示了通过RF离子辅助技术在大HE气电池中有效运输离子。我们还制造了一个非常精细的RF电极的漏斗结构，高达0.3毫米，尽管在演示工作中未测试使用磁场，但我们确定它将有效地提高细胞的有效停止能力。较少的