ECR源低能强流高电荷态离子束四维发射度测量仪的研制

为全面研究ECR（Electron Cyclotron Resonance）离子源引出的高电荷态离子束流品质，获取ECR离子源引出离子束流的横向四维相空间分布，提高向加速器的注入效率，中国科学院近代物理研究所研制了一台高精度Pepper Pot型发射度测量仪PEMiL（Pepper pot Emittance Meter in Lanzhou）。根据使用需求，利用KBr晶体喷涂技术取代传统的CsI闪烁体成像技术，解决了束流光斑重叠效应，获得了边界清晰的束流图像；并开发了相应的数据处理分析程序，以分析处理得到的束流横向四维相空间分布。利用PEMiL获得了75 keV，170 eμA的O5+束流横向四维发射度。分析结果表明:PEMiL测量分析后的束流发射度结果可靠性高，荧光屏电荷累积效应造成的发射度差异不超过25%，PEMiL可作为ECR离子源引出离子束流品质诊断的有效装置。

Development of a Four-dimensional Emittance Meter for the Diagnostics of High Intensity Highly Charged Ion Beam From an Electron Cyclotron Resonance Ion Source

To study the four-dimensional (4D) emittances of the ion beams extracted from a highly charged ion source, so as to improve the ion beam coupling efficiency to downstream accelerators, a Pepper Pot type emittance probe PEMiL (Pepper pot Emittance Meter in Lanzhou) has been developed at Institute of Modern Physics (IMP). Based on the application requirements, the typical parameters of PEMiL have been refined. In the development, we utilized a quartz glass target sprayed uniformly with KBr powder as the scintillator instead of the traditional CsI scintillator to mitigate the overlapping effect of ion beam spot images, which has been validated with the measured results that the beam spot overlapping error vanishes and clear boundary spots has been obtained. For this 4D emittance probe, corresponding data processing and analyzing code has also been developed, so as to give the detailed transverse beam quality information of the incident beam in 4D phase space. In this paper, we will present the technical details about the structure design, fabrication and data processing of PEMiL. The preliminary test results of a 75 keV, 170 eμA O5+ beam emittance will also be measured. The analysis results show that beam emittance measured by PEMiL reveals a high reliability, the emittance difference that was caused by the charge accumulation effect of scintillator is lower than 25%, and PEMiL can be used as an efficient meter for the ECR ion source extracted beam property diagnostic.