1．06μm激光辐照金盘靶的软X光转换

SOFT X-RAY CONVERSION FROM Au DISK IRRADIATED BY 1.06μm LASER

在１．０６μｍ激光辐照金盘靶实验中，利用坪响应Ｘ光二极管探测器（ｐｌａｔｅａｕｒｅｓｐｏｎｓｅＸ一ｒａｙｄｉｏｄｅ）测量了软Ｘ光能量（０．１～１５ｋｅＶ）角分布，得到了软Ｘ光转换效率。实验条件：激光波长λ＿Ｌ＝１．０６μｍ，Ｅ＿Ｌ＝６０～５００Ｊ，τ＿ｐ≈８００ｐｓ，ｆ／１．７，Ｉ＿Ｌ＝１０￣（１３）～１０￣（１４）Ｗ／ｃｍ￣２。实验结果表明：软Ｘ光能量角分布粗略呈ａ＋ｂｃｏｓθ分布，软Ｘ光转换效率随激光强度的增加而降低。当靶面激光焦斑直径２３５μｍ，激光强度约５．０×１０￣（１４）Ｗ／ｃｍ￣２时，软Ｘ光转换效率约３１．０％。

Abstract We measured the angular distribution of the soft X-ray energy(0.1～1.5keV)and acquiredthe soft X ray conversion efficiency using the plateau response X ray diode detectros(XRD)￣[8] in experiments of Au disk target irradiated by 1. 06μm laser。In our experiments we used one beam of the“Sheng Guang I”laser facility and the laserparameters are as follows :λ_L 1.06μm,E_L 60～500J,laser FWHM 700～1000ps,f/1.7,I_L 10￣(13)～10￣(14) Wl/cm￣2, laser spot diameter about 235μm and 300μm,laser incident angle 10°,30°,and45°. I_L changed with incident E_L. The construction of Au disk target is shown in Fig.1. Theinteraction between laser and target is shown in Fig.2.The positiolis of XRD in target chamberare shown in Fig. 3.The signal from XRD was recorded by the fast response oscilloscope in our experiments.One ofthe typical signals is shown in Fig.4.In order to acquire the soft X-ray energy from the Au diskirradiated by 1.06μm laser, first of all,we assumed that the distribution of the soft X-ray issymmetrical centering on the normal of the target, secondly,we could find a fit formula from the softx-ray energy ofthe discrete point in space,finally,we integrated the soft X-ray energy in space.The energy distribution of the soft X-ray acquired from the experiments of the Au diskirradiated by 1.06μm laser is shown in Fig.5.The relation curve between the soft X-rayconversion efficiency and the laser intensity is shown in Fig.6.We can make conclusions as follows:(1)The angular distribution of the soft X-ray energy in the experinents of Au disk irradiatedby 1.06μm laser shows approximately the distribution of a+bcosθ,and the soft X-ray conversionefficiency decreases with the increase of laser intensity. (2)The soft X-ray conversion efficiency is about 3 1.0% when the laser spot diameteris 235μm,laser FWHM is 800～900ps,and the laser intensity is about 5.0 × 10￣(14)W/cm￣2 (3)The soft x ray conversion efficiency is not very apparently dependent on the θ.The results from the experiments nearly correspond with the one from the theory.