Emittance growth mechanisms for laser-accelerated proton beams.
Emittance growth mechanisms for laser-accelerated proton beams.
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DOI：
10.1103/physreve.75.056401
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发表时间：
2007-05
期刊：
影响因子：
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通讯作者：
A. Kemp;J. Fuchs;Y. Sentoku;V. Sotnikov;M. Bakeman;P. Antici;T. Cowan
中科院分区：
文献类型：
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作者：
A. Kemp;J. Fuchs;Y. Sentoku;V. Sotnikov;M. Bakeman;P. Antici;T. Cowan
在最近的实验中，发现激光加速MeV离子束的横向归一化均方根发射度<0.002mmmrad，比加速器中使用的热离子源的发射度至少小100倍[T. E.科万，物理学评论快报。92，204801（2004）]。我们通过研究几种候选的发射度增长机制，研究了激光加速质子束低发射度的起源。作为我们的主要工具，我们使用的分析模型和一维和二维粒子在细胞模拟，已被修改，包括粒子之间的二元碰撞。我们发现，发射率的主要来源是驱动离子加速的激光产生的热电子喷流。在离子被加速之前发生的冷电子-离子碰撞对最终发射率的贡献小于10%。我们的结果与实验定性一致，我们提出了一个精致的分析发射度温度，一个更好的代表的基本光束物理。
In recent experiments the transverse normalized rms emittance of laser-accelerated MeV ion beams was found to be < 0.002 mm mrad, which is at least 100 times smaller than the emittance of thermal ion sources used in accelerators [T. E. Cowan, Phys. Rev. Lett. 92, 204801 (2004)]. We investigate the origin for the low emittance of laser-accelerated proton beams by studying several candidates for emittance-growth mechanisms. As our main tools, we use analytical models and one- and two-dimensional particle-in-cell simulations that have been modified to include binary collisions between particles. We find that the dominant source of emittance is filamentation of the laser-generated hot electron jets that drive the ion acceleration. Cold electron-ion collisions that occur before ions are accelerated contribute less than ten percent of the final emittance. Our results are in qualitative agreement with the experiment, for which we present a refined analysis relating emittance to temperature, a better representative of the fundamental beam physics.