Monoenergetic ion beams from ultrathin foils irradiated by ultrahigh-contrast circularly polarized laser pulses
Monoenergetic ion beams from ultrathin foils irradiated by ultrahigh-contrast circularly polarized laser pulses
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DOI：
10.1103/physrevstab.11.031301
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发表时间：
2008-03
影响因子：
--
通讯作者：
O. Klimo;J. Psikal;J. Limpouch;V. Tikhonchuk
中科院分区：
文献类型：
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作者：
O. Klimo;J. Psikal;J. Limpouch;V. Tikhonchuk
利用一维和二维粒子模拟方法研究了强圆偏振激光脉冲对离子加速的影响。圆偏振激光波加热电子的效率远低于线性偏振波，离子加速过程发生在箔的前侧。在箔中包含的所有离子都被加速之后，箔的弹道演化变得重要。在加速过程中，整个箔被加速为一个致密的准中性等离子体束，这意味着离子的能谱是准单能的。由于弹道演化，被加速的离子束的速度扩展被保持，而离子的平均速度可以进一步增加。这提供了控制加速离子束的参数的可能性。离子加速过程是由激光束到箔的动量转移来描述的，即使箔包含相当数量的轻离子或一些表面污染物，它也可以相当有效地将能量转移到重离子。二维模拟证实了离子的准单能谱的形成和离子束的相对良好的准直，然而激光强度的空间分布对离子束的最大速度构成限制。本文提出的离子加速机制可能适用于获得高密度的准单能重离子束流，并可用于核物理实验。我们的模拟是由一个简单的理论模型，它提供了关于如何控制加速d离子的能量，数量和能量扩散的见解。
Acceleration of ions from ultrathin foils irradiated by intense circularly polarized laser pulses is investigated using one- and two-dimensional particle simulations. A circularly polarized laser wave heats the electrons much less efficiently than the wave of linear polarization and the ion acceleration process takes place on the front side of the foil. The ballistic evolution of the foil becomes important after all ions contained in the foil have been accelerated. In the ongoing acceleration proce ss, the whole foil is accelerated as a dense compact bunch of quasineutral plasma implying that the energy spectrum of ions is quasimonoenergetic. Because of the ballistic evolution, the velocity spread of an accelerated ion beam is conserved while the av erage velocity of ions may be further increased. This offers the possibility to control the parameters of the accelerated ion beam. The ion acceleration process is described by the momentum transfer from the laser beam to the foil and it might be fairly e fficient in terms of the energy transferred to the heavy ions even if the foil contains a comparable number of light ions or some surface contaminants. Two-dimensional simulations confirm the formation of the quasimonoenergetic spectrum of ions and relati vely good collimation of the ion bunch, however the spatial distribution of the laser intensity poses constraints on the maximum velocity of the ion beam. The present ion acceleration mechanism might be suitable for obtaining a dense high energy beam of q uasimonoenergetic heavy ions which can be subsequently applied in nuclear physics experiments. Our simulations are complemented by a simple theoretical model which provides the insights on how to control the energy, number, and energy spread of accelerate d ions.