Short-pulse high-intensity laser-generated fast electron transport into thick solid targets
Short-pulse high-intensity laser-generated fast electron transport into thick solid targets
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DOI：
10.1103/physreve.56.7193
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发表时间：
1997-12-01
影响因子：
2.4
通讯作者：
Guerin, SM
中科院分区：
文献类型：
--
作者：
Davies, JR;Bell, AR;Guerin, SM
本文用相对论性Fokker-Planck方程研究了波长为1 μ m、光斑直径为20 μ m、峰值强度为2 × 10 ~（18）W·cm ~（-2）的激光脉冲产生的快电子在固体铝靶上的输运。背景由E=eta j（B）表示，其中eta是电阻率，j（B）是背景电流密度。碰撞，电场和磁场，以及电阻率的变化，由于加热的背景。假设旋转对称。该处理是有效的快电子数密度远小于背景，快电子能量远大于背景温度，和时间尺度足够短，磁扩散和热传导可以忽略不计。忽略电离也限制了模型的有效性。电场和磁场变得重要的强度进行评估。电场降低了穿透靶的快速电子的能量。磁场减小了径向扩散，增加了中间能量快电子的穿透，并反射了较低能量的快电子。电阻率的变化显著影响场的产生。K α发射诊断的影响进行了讨论。
The transport of fast electrons generated by 1 ps, 1 mu m wavelength laser pulses focused to spot diameters of 20 mu m and peak intensities of up to 2x10(18) W cm(-2) on to solid aluminum targets is considered using a relativistic Fokker-Planck equation, which is solved by reducing it to an equivalent system of stochastic differential equations. The background is represented by E=eta j(b), where eta is the resistivity and j(b) is the background current density. Collisions, electric and magnetic fields, and changes in resistivity due to heating of the background are included. Rotational symmetry is assumed. The treatment is valid for fast electron number densities much less than that of the background, fast electron energies much greater than the background temperature, and time scales short enough that magnetic diffusion and thermal conduction are negligible. The neglect of ionization also limits the validity of the model. The intensities at which electric and magnetic fields become important are evaluated. The electric field lowers the energy of fast electrons penetrating the target. The magnetic field reduces the radial spread, increases the penetration of intermediate energy fast electrons, and reflects lower energy fast electrons. Changes in resistivity significantly affect the field generation. The implications for K alpha emission diagnostics are discussed.