The effects of magnetic vortex acceleration (MVA) are investigated with two-dimensional particle-in-cell (PIC) simulations by laser interaction with near-critical density (NCD) plasma inside a hollow conical plasma. Energetic and collimated proton beams can be accelerated by a longitudinal charge-separation field. Energetic protons with a peak energy of 220 MeV are produced in PIC simulations. Compared with a uniform NCD plasma, both the cutoff energy and collimation of proton beams are improved remarkably. Furthermore, the influence of different gap sizes of cone tip is taken into account. For optimizing magnetic vortex acceleration, the gap size of the cone tip is suggested to match the focal spot size of laser pulse.

中文翻译：

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激光与空心锥形靶内近临界密度等离子体的相互作用增强磁涡旋加速

通过激光与空心锥形等离子体内的近临界密度 (NCD) 等离子体的相互作用，通过二维细胞内粒子 (PIC) 模拟研究了磁涡旋加速 (MVA) 的影响。高能和准直的质子束可以通过纵向电荷分离场加速。在 PIC 模拟中产生峰值能量为 220 MeV 的高能质子。与均匀的NCD等离子体相比，质子束的截止能量和准直度都有显着提高。此外，还考虑了锥尖不同间隙尺寸的影响。为了优化磁涡旋加速度，建议锥尖的间隙尺寸与激光脉冲的焦斑尺寸相匹配。