A short and high-intensity neutron pulse can be produced efficiently by using photonuclear reactions caused by Bremsstrahlung hard X-rays in a lase-irradiated high-Z target. The efficient and repetitive neutron generation was demonstrated with the combination of 1 Hz, 0.5 J, 25 fs, 5 × 1019 W/cm2 laser pulses and a rotating tungsten disc targe. Here we applied double laser pulse irradiation scheme to increase the neutron generation efficiency. The first low-intensity laser pulse produces a long-scale under-critical-density plasma on the tungsten target surface prior to the second pulse irradiatio. High energy electrons above the ponderomotive scaling value are accelerated by the second hig-intensity pulse in the preformed plasm, this results in the increment of hard X-ray photons and photonuclear neutron. 3.5 × 104 neutron/pulse was obtained with optimized laser irradiation conditions.
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机译：通过使用由l致辐射的硬X射线在激光辐照的高Z目标中引起的光核反应，可以有效地产生短而高强度的中子脉冲。结合1 Hz，0.5 J，25 fs，5×1019 W / cm2激光脉冲和旋转的钨圆盘靶，证明了有效且重复的中子产生。在这里我们应用了双激光脉冲辐照方案来提高中子产生效率。在第二脉冲辐照之前，第一低强度激光脉冲在钨靶表面上产生长尺度的低于临界密度的等离子体。预先形成的等离子体中的第二高强度脉冲会加速高于动能定标值的高能电子，从而导致硬X射线光子和光核中子的增加。在优化的激光辐照条件下获得了3.5×104个中子/脉冲。
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