Study of efficient ion acceleration by a laser beam

用三维粒子模拟方法研究了激光脉冲照射圆盘靶时的离子加速过程。结果表明，使用一种“轻”材料作为靶材，可以有效地将质子加速到高能，因为在这种材料中，靶材会发生更强的库仑爆炸。此外，由于加速的质子，离子云也产生了很大的移动。这种不断膨胀和移动的离子云有效地加速了质子的运动，通过以氢为靶，可以产生能量为200 MeV、能散度为2%的质子束。在聚乙烯靶中，质子和碳离子形成两层。强烈的库仑爆炸和每一层之间的库仑斥力会导致高能质子的产生。掺杂的靶会变成双层。然后这种双层结构导致了准单能质子束的产生。

Ion acceleration with irradiating a disk target by a laser pulse is studied by 3D particle-in-cell simulations. It was shown that protons are accelerated efficiently to high energy by using a "light" material for a target, because a stronger Coulomb explosion of the target occurs within such a material. Moreover, a large movement of the ion cloud for the accelerated protons is produced. This expanding and moving ion cloud accelerates protons effectively.By using hydrogen for the target, one can generate a proton beam with an energy of 200 MeV and an energy spread of 2%. In a polyethylene target, protons and carbon ions form two layers. A strong Coulomb explosion and Coulomb repulsion between each layer induces a generation of high energy protons. A doped target becomes a double layer. Then this double layer structure causes a generation of a quasi-monoenergetic proton beam.