激光平面靶3ω0/2谐波空间精细结构的时间和光谱特性

我们从实验上观察到3ω₀/2谐波沿90°辐射精细结构,并从运动细丝底部附近n_c/4处辐射3ω₀/2谐波来解释3ω₀/2谐波细丝结构的存在;从运动的细丝底部对TPD带来的Doppler修正解释3ω₀/2谐波的双峰结构以及红强蓝弱的特点,数量上对红移、蓝移的估算与实验大体相符。用宽带激光打靶,由于靶面照明均匀及宽频带作用,细丝不易形成,对抑制TPD产生的超热电子可能是有益的。 关键词：

TEMPORAL AND SPECTRAL FEATURE OF THE 3(ω0)/2 SPATIALLY FINE STRUCTURES IN LASER IRRADIATED PLANAR TARGETS

Both temporally and Spectrally resolved fine structures of 90° lateral 3/2ω₀ harmo-nic emission were experimentally observed. The existence of 3/2ω₀ harmonic filaments isattributed to the 3/2ω₀ harmonic radiation emitted from neighborhood of the bottom ofmoving filament, about n_c/4 away from it. The double hump structure with intensered hump of laterally emitted 3/2ω₀ spectrum can also be explained by Doppler correc-tion besides the thermal correction due to fast moving TPD process occuring in the unstable filaments. Estimation of both red and blue shifts using our simple model is wellconsistent with experimental results. Experiments showed that the 3/2ω₀ emission wasobviously suppressed by using broad band laser owing to more uniform illumination on the target surface and broad band effect. These may be promissing for superhot electron suppression.