强激光等离子体中电子热传导的数值模拟

Numerical Simulation of Electron Thermal Conduction in Ultraintence-laser Plasma Interaction

为了理解超强激光与等离子体相互作用中产生的电子热传导特性,采用相对论电磁粒子模拟程序,估算了激光功率密度下,在等离子体表面所形成的热能和热流的空间分布,得到了超热电子和经典SpitzerHarm理论描述的电子热流随时间的演化情形。结果表明,在飞秒强激光脉冲作用下产生的等离子体,温度梯度非常大,以致电子的热自由程超过温度梯度的标尺长度,因此,不能使用经典的局域型热传导模型,而用的非局域型热传导模型。

In order to understand the electron thermal conduction characteristics in the process of the interaction between ultra-intense laser and plasma,the spatial distribution of the Temperature( thermal energy) and Heat flux laser power density were estimated by means of electromagnetic relativistic particle-in cell program simulation. The electron-thermal evolvement phenomenon was observed as described by the Spitzer-Harm theory. The results show that In intense femtosecond laser pulse,plasma generated under the action of temperature gradient is very large,so that the hot electronic free path is larger than the temperature gradient scale length. Therefore,the local thermal conduction model can not be used; instead the non local thermal conduction model must be used