Li X F, Gibbon P, Hützen A, Büscher M, Weng S M, Chen M, Sheng Z M
Institute for Advanced Simulation, Jülich Supercomputing Centre, Forschungszentrum Jülich, 52425 Jülich, Germany.
Key Laboratory for Laser Plasmas (Ministry of Education), School of Physics and Astronomy, Shanghai Jiao Tong University, Shanghai 200240, China.
Phys Rev E. 2021 Jul;104(1-2):015216. doi: 10.1103/PhysRevE.104.015216.
The production of polarized proton beams with multi-GeV energies in ultraintense laser interaction with targets is studied with three-dimensional particle-in-cell simulations. A near-critical density plasma target with prepolarized proton and tritium ions is considered for the proton acceleration. The prepolarized protons are initially accelerated by laser radiation pressure before injection and further acceleration in a bubblelike wakefield. The temporal dynamics of proton polarization is tracked via the Thomas-Bargmann-Michel-Telegdi equation and it is found that the proton polarization state can be altered by both the laser field and the magnetic component of the wakefield. The dependence of the proton acceleration and polarization on the ratio of the ion species is determined and it is found that the protons can be efficiently accelerated as long as their relative fraction is less than 20%, in which case the bubble size is large enough for the protons to obtain sufficient energy to overcome the bubble injection threshold.
利用三维粒子模拟研究了超强激光与靶相互作用产生多GeV能量极化质子束的过程。质子加速采用了具有预极化质子和氚离子的近临界密度等离子体靶。预极化质子在注入前首先由激光辐射压力加速，并在泡状尾波场中进一步加速。通过托马斯-巴格曼-米歇尔-特勒格迪方程跟踪质子极化的时间动态，发现质子极化状态可由激光场和尾波场的磁场分量改变。确定了质子加速和极化对离子种类比例的依赖性，发现只要质子的相对分数小于20%，质子就能被有效加速，在这种情况下，泡的尺寸足够大，质子能够获得足够的能量来克服泡注入阈值。
