The unexpected role of evolving longitudinal electric fields in generating energetic electrons in relativistically transparent plasmas
The unexpected role of evolving longitudinal electric fields in generating energetic electrons in relativistically transparent plasmas
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DOI：
10.1088/1367-2630/aae034
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发表时间：
2018-08
影响因子：
3.3
通讯作者：
L. Willingale;A. Arefiev;G. Williams;G. Williams;Hui-Hwa Chen;F. Dollar;A. Hazi;A. Maksimchuk;M. Manuel;E. Marley;E. Marley;W. Nazarov;T. Zhao;C. Zulick
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文献类型：
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作者：
L. Willingale;A. Arefiev;G. Williams;G. Williams;Hui-Hwa Chen;F. Dollar;A. Hazi;A. Maksimchuk;M. Manuel;E. Marley;E. Marley;W. Nazarov;T. Zhao;C. Zulick
在强激光脉冲与相对论透明靶相互作用中，实验观测到了超动能电子。对于一个相对论透明的目标，动力学建模表明，能量电子的产生主要是由能量转移内的主要，经典过密，等离子体体积。激光脉冲在等离子体体积内产生狭窄的漏斗状通道，该通道产生负责电子加热的场结构。场结构结合了由强激光驱动的纵向电子流产生的缓慢演变的方位角磁场，以及意外地由漏斗状通道的壁的反射产生的强传播纵向电场。磁场通过偏转辅助激光脉冲的横向电场对电子进行加热，而纵向电场直接在正向方向上加速电子。由反射产生的纵向电场比入射激光束中的强30倍，并且所产生的直接激光加速贡献了由激光脉冲的横向电场转移到超有质动力尾部的电子的能量的大约三分之一。
Superponderomotive-energy electrons are observed experimentally from the interaction of an intense laser pulse with a relativistically transparent target. For a relativistically transparent target, kinetic modeling shows that the generation of energetic electrons is dominated by energy transfer within the main, classically overdense, plasma volume. The laser pulse produces a narrowing, funnel-like channel inside the plasma volume that generates a field structure responsible for the electron heating. The field structure combines a slowly evolving azimuthal magnetic field, generated by a strong laser-driven longitudinal electron current, and, unexpectedly, a strong propagating longitudinal electric field, generated by reflections off the walls of the funnel-like channel. The magnetic field assists electron heating by the transverse electric field of the laser pulse through deflections, whereas the longitudinal electric field directly accelerates the electrons in the forward direction. The longitudinal electric field produced by reflections is 30 times stronger than that in the incoming laser beam and the resulting direct laser acceleration contributes roughly one third of the energy transferred by the transverse electric field of the laser pulse to electrons of the super-ponderomotive tail.