利用射频腔对激光加速质子能谱的优化  

Energy spectrum optimization of laser-produced protons by RF cavity

作　　者：滕建[1] 谷渝秋[1] 洪伟[1] 朱斌[1] 余金清[1,2] 赵宗清[1] 曹磊峰[1] 

机构地区：[1]中国工程物理研究院激光聚变研究中心,四川绵阳621900 [2]电子科技大学物理电子学院,成都610054

出　　处：《强激光与粒子束》2012年第2期467-470,共4页High Power Laser and Particle Beams

基　　金：国家自然科学基金项目(10975121;11175165;10905051);国家高技术发展计划项目

摘　　要：基于靶背鞘层加速机制(TNSA)产生的质子束具有宽能谱的特性,限制了其应用范围。为了产生准单能质子束,研究了基于直线加速器射频腔结构的质子能谱优化方法。在给定射频腔电压和频率情况下,计算了腔间距随优化能量的变化关系,并针对不同优化能量设计了不同大小的腔间距和腔数。在给定腔数情况下,发现只在某个能量附近可以获得单能性最好的单能峰。对能量接受范围进行了分析,要实现最终2%的能散,进入射频腔的质子束能散不能大于15%,并分析了射频腔频率对能量接受范围的影响。最后对PIC模拟得到的半高全宽为15%的一个能谱进行优化,获得了谱宽小于2%的准单色质子能谱。The proton beam accelerated by target normal sheath acceleration （TNSA） mechanism has a wide energy spectrum, which limits its applications. In order to produce quasi-monoenergetic proton beams, the energy spectrum optimization method based on RF cavity has been investigated. At given RF voltage and frequency, the relationship of the cavity length and the optimization energy was calculated and spectrum optimization with different cavity lengths and cavity numbers was designed for different energy. For given number of cavities, only a certain energy range can get the minimum energy divergence. The energy acceptance has been analyzed. To get the final energy divergence of 2 %, the energy divergence of the proton beam before entering RF cavity should not be over 15%. The energy acceptance affected by the RF frequency has also been analyzed. Finally a spectrum calculated by the particle-in-cell simulation with the divergence about 15% was optimized through the RF cavity, and a quasi- monoenergetic proton beam with the energy divergence lower than 2 % was obtained.

关 键 词：质子能谱 能散 射频腔 能量接受范围 

分 类 号：O539[理学—等离子体物理] O572.21[理学—物理]