团簇在超强超短脉冲激光场中的演化

Evolvement of deuterium clusters in ultrashort ultraintense laser field

利用低温脉冲气阀产生氘团簇束,在SILEX-Ⅰ激光装置上开展实验,研究氘团簇在超强超短脉冲激光场中的演化过程,获得了数十keV的高能氘离子,这些氘离子的能谱分布与库仑爆炸模型计算结果一致。实验结果表明,在一定的激光功率密度条件下,团簇的平均尺度决定了释放出高能离子的能谱分布。激光辐照团簇后,通过阈上电离部分电子逃逸团簇,随着初始电离电子屏蔽作用加强,碰撞电离变成了团簇的主要电离机制。

With large deuterium clusters produced in a supersonic expansion of high pressure gases into vacuum through a cone nozzle,experiments have been carried out to investigate the evolvement of deuterium clusters in ultrashort ultraintense laser field based on the SILEX-Ⅰ laser system.Tens keV deuterium ions were observed.The energy spectrum of these ions agrees with the Coulomb explosion model.It is found that distribution of the energy spectrum is determined by the average size of clusters.A part of electrons escape from the clusters by above threshold ionization after laser irradiation,and then collision ionization starts to dominate with the enhanced screening effect produced by the initial ionization electrons.