Habara H, Kodama R, Sentoku Y, Izumi N, Kitagawa Y, Tanaka K A, Mima K, Yamanaka T
Institute of Laser Engineering, Osaka University, Suita, 565-0871 Osaka, Japan.
Phys Rev E Stat Nonlin Soft Matter Phys. 2004 Mar;69(3 Pt 2):036407. doi: 10.1103/PhysRevE.69.036407. Epub 2004 Mar 24.
In order to study the ion acceleration processes in ultraintense laser-plasma interactions with solid targets, neutron spectra from deuteron-deuteron (D-D) nuclear reactions were measured. Spectra were obtained when (50-100 TW, 0.5-1 ps) laser light irradiated obliquely incident deuterated plastic targets as a function of laser polarization, intensity, and density scale length of the preformed plasma. The experimental data are compared with three-dimensional Monte Carlo simulations. The results indicate that the ion momentum distribution is collimated and directed into the bulk of the target to the target normal direction with an energy that is linearly proportional to the laser intensity. The distribution of the accelerated ions was observed to change from isotropic to anisotropic with laser prepulse intensity. All the results indicate that the ion acceleration is dominated by an electrostatic field generated from a charge displacement of the hot electrons at the target surface.
为了研究超强激光与固体靶相互作用中的离子加速过程，测量了氘 - 氘（D-D）核反应产生的中子能谱。当（50 - 100太瓦，0.5 - 1皮秒）的激光斜入射氘化塑料靶时，作为激光偏振、强度和预形成等离子体密度标长的函数获取了能谱。将实验数据与三维蒙特卡罗模拟进行了比较。结果表明，离子动量分布被准直并沿靶的法线方向指向靶体内部，其能量与激光强度成线性比例。观察到加速离子的分布随激光预脉冲强度从各向同性变为各向异性。所有结果表明，离子加速主要由靶表面热电子电荷位移产生的静电场主导。
