Two-dimensional particle-in-cell simulations show that when an intense picosecond laser pulse irradiates a target with steep but smooth density profile, the target protons can be accelerated to high energies with small divergence by a combination of target normal sheath acceleration and radiation pressure acceleration. The effects of plasma density profile on proton acceleration and collimation are investigated. In general, smaller(larger) density gradients lead to larger(smaller) self-generated azimuthal magnetic fields and smaller(larger) target-back electrostatic sheath fields, and thus proton beams with smaller(larger) divergence angle as well as cutoff energy. Accordingly, within limits, proton beams with desired peaked spectrum, energy, and divergence angle can be obtained by tailoring the target density profiles. It is also demonstrated that target tailoring can be achieved by having two suitable nanosecond lasers separately irradiating the front and back sides of a unifo...

中文翻译：

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使用量身定制的目标密度曲线操纵激光驱动的质子加速

二维单元格粒子模拟显示，当皮秒级高强度激光脉冲以陡峭但平滑的密度分布辐照目标时，可以通过目标正常鞘层加速度和辐射压力的组合，将目标质子加速至高能量且发散度较小。加速。研究了等离子体密度分布对质子加速和准直的影响。通常，较小（较大）的密度梯度会导致较大（较小）的自生方位磁场和较小（较大）的靶背静电鞘电场，因此会产生具有较小（较大）发散角和截止能量的质子束。因此，在限定范围内，可以通过调整目标密度分布来获得具有所需峰值光谱，能量和发散角的质子束。