Numerical simulation of electron thermal conduction phenomena in femto second-laser plasma interaction
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摘要: 采用相对论电磁粒子模拟程序研究了飞秒激光等离子体相互作用中产生的电流密度、电场和自生磁场的发展演化过程。介绍了电子的非局域热输运的基本特性以及激光加热过程中温度烧蚀前沿稠密等离子体子区的预热效应、临界面附近的限流效应,以及冕区的反扩散与限流效应,得到了经典Spitzer-Harm理论描述的电子热传导随自生磁场的演化情形。数值模拟表明:在线性强激光作用下,由于电子初始时刻的无规则热运动,在等离子体上激发电磁不稳定性,而不稳定性激发的强电磁场使电子束在非常短的距离内沉积能量,同时对在激光有质动力推开电子时形成的超热电子能量输运产生抑制作用。Abstract: The spatio temporal evolution of current density, electric field and self-generated magnetic field in ultraintense laser-plasma interactions are studied by electromagnetic relativistic particle-in-cell program. The main characteristics of nonlocal electron transport are briefly described for laser-produced plasmas, which include the effects of preheating in overdense region, flux inhabitation near critical surface and anti-diffusion in coronal region. The temporal evolution electron thermal conduction with the self-generated magnetic field description of classical Spitzer-Harm theory is obtained. The numerical simulation result shows that electromagnetic instability is excited in the plasma because of the random thermal motion of electrons under irradiation of the linear polarized femtosecond laser. It is the strong magnetic field excited by instability which makes the electron beam deposit energy within very short distance. Meanwhile, it restrains the electron thermo current when the laser ponderomotive force bursts through the electrons.
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