飞秒激光作用下高能离子产生的实验研究

Experimental study of femtosecond laser-introduced generation of high energy io ns

摘要:

为了探索飞秒脉冲激光与固体靶相互作用中高能 离子的能量分布特性,在超短超 强激光装置“SILEX-I”上进行了超强激光与平面薄膜Cu靶的相互作用中高能离子能谱分布 的实验研究。采用固体核径迹探测器CR39和Thomson离子谱仪相结合 的方式,在固体 靶背表面法线方向测量了质子和C离子能量分布和产额。结果显示,同时测量到了 H⁺质子和C1＋、C2＋、C3＋和C4＋信号,离子沿靶背法线 方向发射,离子出现能量截断, 离子的截止能量之比为1∶2∶3∶4。在CR39上 质子信号比C离子信号强,质子产额远高于C 离子产额；在同一发打靶中,C1＋、C2＋、C3＋和C⁴⁺随着 荷质比的减小,相应的离子的截 止能量也在减小。这一结果将为惯性约束聚变(ICF)“快点火”方案的可行性分析提供参 考依据。

Abstract:

To study the distribution characteristics of high energy ions in the interaction with femtosecond pulse laser with solid targets,high energy ions behavior at the norm al direction of the rear surface of the target produced from ulintencity pulse lase r irradiated Cu thin film solid targets is explored on SILEX-I laser facility.T he solid nuclear detector CR39and Thomson spectrum are used to detect the energy spectra of protons and carbon ions.Protons H⁺ and carbon ions C¹⁺,C²⁺,C ³⁺ and C⁴⁺ have been observed.In addition,the results show that the ions are cut-off at a cer tain energy,and the ratio of the maximum cut-off energy of the C¹⁺,C²⁺ ,C³⁺ and C⁴⁺ ions is about 1∶2∶3∶4.Moreover,the carbon ions traces are much weaker than the p rotons trace,so the yields of protons can be much higher than carbon ions,and the proto ns have the screening effect on the carbon ions.And the cut-off energy of the carbon ion is increased with the charge-to-mass ratio in the same shot.The results will provide the reference for inertial confinement fusion (ICF) “quick ignition” f easibility analysis.