Schwarz S, Baumann T M, Kittimanapun K, Lapierre A, Snyder A
National Superconducting Cyclotron Laboratory (NSCL), Michigan State University, East Lansing, Michigan 48824, USA.
Rev Sci Instrum. 2014 Feb;85(2):02B705. doi: 10.1063/1.4827109.
The Electron Beam Ion Trap (EBIT) in NSCL's reaccelerator ReA uses continuous ion injection and accumulation. In order to maximize capture efficiency and minimize breeding time into high charge states, the EBIT requires a high-current/high current-density electron beam. A new electron gun insert based on a concave Ba-dispenser cathode has been designed and built to increase the current transmitted through the EBIT's superconducting magnet. With the new insert, stable EBIT operating conditions with 0.8 A of electron beam have been established. The design of the electron gun is presented together with calculated and measured perveance data. In order to assess the experimental compression of the electron beam, a pinhole CCD camera has been set up to measure the electron beam radius. The camera observes X-rays emitted from highly charged ions, excited by the electron beam. Initial tests with this camera setup will be presented. They indicate that a current density of 640 A/cm(2) has been reached when the EBIT magnet was operated at 4 T.
国家超导回旋加速器实验室（NSCL）的重加速器ReA中的电子束离子阱（EBIT）采用连续离子注入和积累。为了使捕获效率最大化并将高电荷态的孕育时间最小化，EBIT需要高电流/高电流密度的电子束。一种基于凹面钡 dispenser 阴极的新型电子枪插入件已被设计并制造出来，以增加通过EBIT超导磁体传输的电流。使用新的插入件，已建立了电子束电流为0.8 A的稳定EBIT运行条件。介绍了电子枪的设计以及计算和测量的导流系数数据。为了评估电子束的实验压缩情况，已设置了一个针孔CCD相机来测量电子束半径。该相机观测由电子束激发的高电荷离子发射的X射线。将展示使用此相机设置的初步测试。测试表明，当EBIT磁体在4 T下运行时，电流密度已达到640 A/cm² 。
