一种应用于HIRFL-CSR上的非拦截式剩余气体电离束流剖面探测器(英文)

Abstract

兰州重离子加速器冷却储存环主环（CSRm）上成功应用了一种剩余气体电离剖面探测器（IPM），这种新型非拦截式剖面探测器的应用服役对CSRm的束流冷却研究及常规调束的实时剖面监测具有重要意义。IPM探测器通过收集束流与剩余气体之间的电离产物（气体离子或电子），利用偏转静电场将电离产物加速至多重微通道板（MCP），并在其上进行电子放大，放大的信号电子随后在荧光屏（P46等）上进行电子-光子转换，最终含有束流剖面信息的投影光子被真空靶室外的CCD相机获取。在正式应用于CSRm之前，IPM探测器还在分离扇回旋加速器直线（SSC Linac）上进行了束流实验，并与传统单丝扫描剖面探测器进行了对比。IPM探测器与单丝刮束器的剖面测量结果相近，并且具有较好的信噪比和约60 μm的较高空间分辨率。这种IPM探测器可以利用电阻串联进行均匀分压，较便捷地应用于真空度较低的直线加速器，还可以改造为分离电极单独供压的结构，应用在超高真空需要烘烤的环形加速器。最后还介绍了一种全新紧凑型结构的IPM探测器设计，该设计利用一套IPM探测器实现束流横向水平与垂直两个方向的剖面测量功能，这种紧凑型IPM结构尤其在空间紧缺型的强流直线加速器上具有重大的应用价值。 A new non-intercepting beam profile monitor, residual gas Ionization Profile Monitor (IPM), has been developed and tested at the main Cooling Storage Ring of Heavy Ion Research Facility in Lanzhou (HIRFL-CSRm). It has been successfully used for studies of electron cooling mechanisms, as well as profile monitoring under normal-mode operation in HIRFL-CSRm. The IPM measures the distribution of ions resulting from the residual gas ionization during the beam passage. The gas ions are collected and multiplied by tandem-type MCPs and a phosphor screen, and eventually captured by a commercial CCD camera outside the vacuum chamber. Before formally applied in HIRFL-CSRm, the IPM was tested and compared with a conventional wire scanner profile monitor at Sector Separated Cyclotron Linac (SSC Linac). Both results show good agreement. Besides, the IPM has higher signal to noise ratio than the wire scanner. It also has a very high spatial resolution of around 60 μm. This monitor can be used for low vacuum like Linac with resistance for bias voltage, or for ultra-high vacuum with discrete electrodes for bias voltage where the bakeout process is essential. Furthermore, a novel and compact design of one IPM with capability of detecting both horizontal and vertical profile is proposed. This compact IPM is quite suitable for non-invasive profile diagnostics at space shortage and high-current Linac.