In this paper, simulation study of electron stochastic heating arising from the Raman backscatter radiations during the interaction of the laser pulse with the nitrogen atoms is presented by use of a massively parallel particle-in-cell code. For this purpose, the self-consistent evolutions of the laser pulse via the time–space Fourier transforms of transvers vector potential are investigated at the different times of propagation. It is shown that since the ionization has effect on the emission of the Raman backscattered radiation; it noticeably contributes on the stochastic heating threshold of the electrons. According to our results, it has been found that, when there is the long rise time laser pulse (here 100 fs), the Raman backscattered radiations are seeded by a strong initial noise at the earlier times. Therefore, by considering the ionization, the necessary condition for chaos threshold is met sooner, which, in turn, causes the electron stochastic heating start quickly compared to the case the laser pulse is propagated in the pre-plasma. As a result, in agreement with chaotic nature of the motion, the electrons gain more energy through the stochastic mechanism in the field-ionized plasma.

中文翻译：

---

强激光脉冲与氮原子相互作用中拉曼背散射辐射引起的电子随机加热

在本文中，通过使用大规模平行粒子在细胞内代码，模拟研究了在激光脉冲与氮原子相互作用期间由拉曼背散射辐射引起的电子随机加热。为此，研究了激光脉冲在不同传播时间通过横向矢量势的时空傅立叶变换的自洽演化。结果表明，由于电离对拉曼背散射辐射的发射有影响；它对电子的随机加热阈值有显着贡献。根据我们的结果，已经发现，当存在长上升时间激光脉冲（此处为 100 fs）时，拉曼背向散射辐射在较早的时间被强初始噪声播种。所以，通过考虑电离，更早满足混沌阈值的必要条件，这反过来又导致与激光脉冲在前等离子体中传播的情况相比，电子随机加热更快地开始。结果，与运动的混沌性质一致，电子通过场电离等离子体中的随机机制获得更多能量。