高能质子束流强度绝对测量的二次电子补偿原理研究

Accurate measurements of high energy proton beam by secondary electron compensation

高能质子入射到金属接收体表面诱发的二次电子直接影响束流强度的测量精度,如何消除二次电子影响是实现束流高精度测量的关键.根据高能带电粒子在金属表面诱发二次电子发射理论,对高能质子束流强度测量的二次电子补偿原理进行了研究,设计了二次电子补偿结构.采用三块金属极板构成的实验装置在高能质子源上开展实验研究,实验测得在中间极板上输出的电流与入射质子束流强度的比值小于0.7%,中间极板上二次电子得到补偿,验证了二次电子补偿原理的正确性.研究表明,采用设计的二次电子补偿结构对高能质子束流强度进行测量时二次电子贡献小于1%.

Accuracy in the measurement of an intense high-energy proton beam is generally disturbed by high energy proton induced secondary electron emission. In the present work,the compensation mechanism for secondary electron emission is investigated for the accurate measurement of high-energy proton beam. An experimental approach with using three metal foils to compensate for secondary electron emission is implemented and described. The experiment is carried out on the HI- 13 tandem accelerator. The current detected from the middle metal foil is 0. 7% of the proton beam. The experimental results show that the measured current of the high-energy proton beam is reliable within 1% .