论文标题
极度强烈激光脉冲的相对性不足等离子体的不透明度
Opacity of relativistically underdense plasmas for extremely intense laser pulses
论文作者
论文摘要
通常认为，相对性不足的等离子体对于强烈的激光辐射是透明的。然而，粒子中的模拟揭示了高于强度阈值的异常激光场吸收，约为$ 3 \ times 10^{24}〜\ mathrm {w} \，\ Mathrm {cmmathrm {cm}^{ - 2} $，对于$ 1〜μ \ mathrm {m Mathrm的波长。在阈值之上，激光强度的进一步增加不会导致传播距离的增加。这些模拟考虑了硬光子的发射以及随后在激光场中的成对光生源。这些效果导致自我维持的电磁级联反应的开始，并形成了激光场内部的致密电子旋转（$ e^+e^ - $）等离子体。血浆可有效吸收该场，从而确保血浆不透明性。讨论了弱纵向电子电场在级联增长中的作用。
It is generally believed that relativistically underdense plasma is transparent for intense laser radiation. However, particle-in-cell simulations reveal abnormal laser field absorption above the intensity threshold about~$3 \times 10^{24}~\mathrm{W}\,\mathrm{cm}^{-2}$ for the wavelength of $1~μ\mathrm{m}$. Above the threshold, the further increase of the laser intensity doesn't lead to the increase of the propagation distance. The simulations take into account emission of hard photons and subsequent pair photoproduction in the laser field. These effects lead to onset of a self-sustained electromagnetic cascade and to formation of dense electron-positron ($e^+e^-$) plasma right inside the laser field. The plasma absorbs the field efficiently, that ensures the plasma opacity. The role of a weak longitudinal electron-ion electric field in the cascade growth is discussed.
