Proton probing of laser-driven EM pulses travelling in helical coils
Proton probing of laser-driven EM pulses travelling in helical coils
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DOI：
10.1017/hpl.2016.47
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发表时间：
2017
影响因子：
4.8
通讯作者：
H. Ahmed;S. Kar;A. Giesecke;D. Doria;G. Nersisyan;O. Willi;C. Lewis;M. Borghesi
中科院分区：
文献类型：
--
作者：
H. Ahmed;S. Kar;A. Giesecke;D. Doria;G. Nersisyan;O. Willi;C. Lewis;M. Borghesi
超强激光脉冲与箔靶相互作用后的超快电荷动力学导致沿连接到靶的导线发射超短、强电磁(EM)脉冲。由于这种激光驱动的电磁脉冲具有很强的电场(数量级为GVm)，因此可以利用行波螺旋几何来控制和优化激光加速质子束的参数。利用质子探测技术研究了电磁脉冲沿螺旋路径的传播。脉冲载流线圈沿横向和平行于线圈轴线的两个垂直方向进行探测。由线圈的横向探测得到的脉冲的时间分布与以前在平面几何中获得的测量结果一致。从线圈的纵向探测获得的数据清楚地表明，质子束发散的能量依赖于减少，这是螺旋线圈靶选择性引导激光驱动离子的机制的基础。
The ultrafast charge dynamics following the interaction of an ultra-intense laser pulse with a foil target leads to the launch of an ultra-short, intense electromagnetic (EM) pulse along a wire connected to the target. Due to the strong electric field (of the order of $\text{GV m}^{-1}$ ) associated to such laser-driven EM pulses, these can be exploited in a travelling-wave helical geometry for controlling and optimizing the parameters of laser accelerated proton beams. The propagation of the EM pulse along a helical path was studied by employing a proton probing technique. The pulse-carrying coil was probed along two orthogonal directions, transverse and parallel to the coil axis. The temporal profile of the pulse obtained from the transverse probing of the coil is in agreement with the previous measurements obtained in a planar geometry. The data obtained from the longitudinal probing of the coil shows a clear evidence of an energy dependent reduction of the proton beam divergence, which underpins the mechanism behind selective guiding of laser-driven ions by the helical coil targets.