飞秒激光作用下质子产额及空间分布

在超短超强激光装置SILEX-Ⅰ上,利用HD810辐射变色膜在靶背法线方向测量了质子产额及空间分布。测量结果显示:光学密度与质子流量密切相关，光学密度越大，质子流量就越大；当C8H8厚度相同，Cu厚度增加时，质子产额随辐射变色膜的光学密度平均值减小而减小；当靶相同，激光功率密度越小时，光学密度平均值就越小，则质子产额也越小；实验中还得到了质子呈环状、成丝和圆盘状结构的空间分布，该空间分布的大小与激光焦斑大小无关。

Yield and spatial distributions of femtosecond laser-produced protons

For studying the yield and spatial distributions of protons produced in the interaction of femtosecond laser with plasmas, protons behavior at the normal direction of the rear surface of the target irradiated by ultra-intensity pulse laser irradiated solid targets was explored on SILEX-I laser facility. The yield and spatial distributions of the protons with different target thicknesses were recorded by radiochromic film (RCF) HD810. The results show that the optics density (OD) is closely correlated with the protons flux, OD values increase with the increasing of proton beam flux; For fixed thickness of C8H8 layer, the proton beam flux and yield of protons and OD of RCF decrease with the increasing Cu layer thickness; for the same thickness of targets, the OD and yield of protons decrease with the decreases of laser intensity;And the corresponding spatial profile of proton beam shows ring-, filament-, and disc-like distribution. The size of the distribution is independent of laser focus.