激光等离子体实验中。许多现象是在微微秒和微米范围内发生的。为了研究这些现象,采用微微秒激光脉冲与高分辨率光学相结合的方法可以提供必要的空间和时间分辨率。实验观察是在碘激光系统AsterixⅢ上进行的。碘激光输出波长为1.3μm,脉冲能量最大输出为300J,脉冲宽度为300ps。靶面功率密度为3×10~(15)W·cm~(-2)相应的半能量点的直径为85μm。利用脉冲宽度为10ps的主被动锁模染料激光脉冲,在与碘激光成90°的方向上,拍摄了时间分辨的阴影照片。同以往的方法相比,染料激光系统作了相当大的改进;特别是染料激光脉冲与碘激光脉冲的同步。染料激光脉冲相对于碘激光脉冲的到达时间可以预先选择,其漂移时间为200ps。所拍得的阴影照片的空间分辨率为10μm。从阴影照片可以看出,除了被加速的冷箔材料之外,还观察到“发丝”、“冲击”等的形成以及沿着靶的表面传导等现象。随着激光强度的增加,这些现象变得愈来愈明显。由于在等离子体与靶架之间存在着很高的电位差,所以对于某些放电现象的观察可能更为可靠。用条纹相机定量地测量了2和10μm厚的塑料薄箔条的膨胀。

Thin plastic foils (2~10 μm thickness) were irradiated with the iodine laser ASTEEIX III (λ=1.3 μm) Pulse energy was 100 J, pulse duration 300 ps; the intensity on target was varied in the range 1014?5x 10炀 W.cm-2- An active-passive mode-locked,fJash -lamp-pumpad dye laser was synchronized with the iodine laser pulse. A siaglo dye ]asei pulse (?10 ps duration) was used to study the gasdynamic motion of the foil matexial during and aifter irradiation by shadowgraphy. Besides the expected acceleration of tZie foil under one-side irradiation we also find strong distuxbaneea of the foil at distances far from the irradiated area, especially at high irxadiances. The results will be discussed and compared with previous, calorimetric measurements of thin foil acceleration.