CO2与Nd:YAG脉冲激光锡等离子体羽辉膨胀特性的研究

为了研究激光光源对极紫外(EUV)等离子体碎屑的影响,采用脉冲Nd:YAG激光与CO2激光激发Sn产生等离子体,基于直接成像法,研究了等离子体羽辉在低气压中的膨胀特性。通过确定等离子体边界,计算出各个角度的等离子体羽辉膨胀边界随时间的变化规律,以及运动动能随运动路径的变化规律。结果表明,气压为10Pa时,在相同激光能量密度(2.5106mJ/cm2)的条件下,CO2脉冲激光作用锡靶产生EUV的等离子体动能小于Nd:YAG脉冲激光作用锡靶产生的等离子体动能;在减缓离子碎屑的研究中,CO2脉冲激光作为EUV的产生光源要优于Nd:YAG脉冲激光。这一结果对研究激光等离子体的应用是有帮助的。

Study on expansion characteristics of tin plasma plume produced by CO2 laser and Nd:YAG laser

In order to study effect of laser on extreme ultraviolet (EUV) plasma debris, CO2 and Nd:YAG pulsed laser was used to produced Sn plasma .Based on direct imaging method , expansion characteristics of plasma plume at low pressure were studied.2-D pictures of Sn plume were taken directly by intensified charge coupled device ( ICCD) and plasma boundary was determined .The time-dependant variation of plasma plume expansion boundary at different angles and the variation of kinetic energy with the change of motion path were calculated .The results show that under the same laser energy density of 2.5 ×106 mJ/cm2 and the atmosphere pressure of 10Pa, EUV Sn plasma kinetic energy produced by Nd:YAG laser is greater than that produced by CO2 laser.CO2 laser is superior to Nd:YAG laser for decreasing plasma debris .This result is helpful for the application of laser plasma .