Solodov A A, Malkin V M, Fisch N J
Princeton Plasma Physics Laboratory, Princeton University, Princeton, New Jersey 08543, USA.
Phys Rev E Stat Nonlin Soft Matter Phys. 2004 Jun;69(6 Pt 2):066413. doi: 10.1103/PhysRevE.69.066413. Epub 2004 Jun 15.
Extremely large laser power might be obtained by compressing laser pulses through backward Raman amplification (BRA) in plasmas. Premature Raman backscattering of a laser pump by plasma noise might be suppressed by an appropriate detuning of the Raman resonance, even as the desired amplification of the seed persists with a high efficiency. In this paper we analyze side scattering of laser pumps by plasma noise in backward Raman amplifiers. Though its growth rate is smaller than that of backscattering, the side scattering can nevertheless be dangerous, because of a longer path of side-scattered pulses in plasmas and because of an angular dependence of the Raman resonance detuning. We show that side scattering of laser pumps by plasma noise in BRA might be suppressed to a tolerable level at all angles by an appropriate combination of two detuning mechanisms associated with plasma density gradient and pump chirp.
通过在等离子体中利用受激拉曼后向放大（BRA）对激光脉冲进行压缩，可以获得极高的激光功率。即使种子光的期望放大能高效持续，通过对拉曼共振进行适当失谐，等离子体噪声对激光泵浦光的过早拉曼背向散射也可能得到抑制。在本文中，我们分析了受激拉曼后向放大器中等离子体噪声对激光泵浦光的侧向散射。尽管其增长率比背向散射的小，但侧向散射仍然可能很危险，这是因为侧向散射脉冲在等离子体中的传播路径更长，以及拉曼共振失谐存在角度依赖性。我们表明，通过与等离子体密度梯度和泵浦啁啾相关的两种失谐机制的适当组合，BRA中等离子体噪声对激光泵浦光的侧向散射在所有角度都可能被抑制到可容忍的水平。
