数值模拟飞秒激光加热金属的热电子发射

研究了超短超强激光脉冲与薄膜靶相互作用中产生的电子热发射.当超短激光脉冲与薄膜靶相互作用时,首先入射超短脉冲激光对吸收深度内的自由电子进行热激发,接下来热激发电子将能量传递到附近的晶格,再通过电子和晶格二体系的热传导,以及电子晶格间的热耦合,将能量传递到材料的内部.因此,电子在皮秒级甚至更短的时间内不能与晶格进行能量耦合,使电子温度超出晶格温度很多,电子热发射就变得非常明显了.用双温方程联合Richardson-Dushman方程的方法对飞秒脉冲激光照射金属靶的电子热发射进行了研究,结果发现电子热发射对飞

Numerical simulation of femtosecond laser heating of metal films using electron thermal emission

The whole process of the electron thermal emission by ultrafast pulsed laser is studied in the paper. When an ultra-short laser pulse interaction with the target film, first of all, the incident laser excites free electrons within the absorption depth; next, electron energy is transferred to nearby lattice through the heat transfer systems of the free electron and lattice, and by the thermal coupling between the electron and the lattice, the energy is delivered to the internal material. Therefore, in a short period of ps and shorter, the energy coupling of the electron and lattice can not be established. So that the electron temperature is much higher than the lattice temperature, the electron thermal emission becomes apparent. The characteristics of thermionic emission of the films during ultrashort pulse laser ablation are investigated using two-temperature model coupled with the Richardson-Dushman equation. It is found that electron thermal emission can significantly change the development of electron and lattice temperatures, meanwhile, the film thickness and laser fluence directly affect electron thermal emission.