ELECTRON ACCELERATIONS AT HIGH MACH NUMBER SHOCKS: TWO-DIMENSIONAL PARTICLE-IN-CELL SIMULATIONS IN VARIOUS PARAMETER REGIMES
ELECTRON ACCELERATIONS AT HIGH MACH NUMBER SHOCKS: TWO-DIMENSIONAL PARTICLE-IN-CELL SIMULATIONS IN VARIOUS PARAMETER REGIMES
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DOI：
10.1088/0004-637x/755/2/109
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发表时间：
2012-04
期刊：
影响因子：
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通讯作者：
Y. Matsumoto;T. Amano;M. Hoshino
中科院分区：
文献类型：
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作者：
Y. Matsumoto;T. Amano;M. Hoshino
利用二维电磁粒子模拟方法研究了不同Alfvén马赫数、离子-电子质量比和上游电子βe（热压力与磁压力之比）条件下高马赫数无碰撞激波中电子的加速。我们发现电子在M/m = 100，βe = 0.5的超高马赫数激波（MA ≥ 30）中得到了有效的加速。电子冲击冲浪加速是一种有效的机制，即使在二维大质量比的粒子向相对论区域加速。在超高马赫数激波中，底部前缘激发的Buneman不稳定性导致了相干静电势结构。虽然多维性允许电子从捕获区域逃逸，但它们可以与强静电场多次相互作用。在各种参数制度的模拟运行表明，电子冲击冲浪加速是一种有效的机制，在超新星遗迹极高的马赫数冲击产生相对论粒子，只要上游电子温度是合理的低。
Electron accelerations at high Mach number collisionless shocks are investigated by means of two-dimensional electromagnetic particle-in-cell simulations with various Alfvén Mach numbers, ion-to-electron mass ratios, and the upstream electron βe (the ratio of the thermal pressure to the magnetic pressure). We find electrons are effectively accelerated at a super-high Mach number shock (MA ∼ 30) with a mass ratio of M/m = 100 and βe = 0.5. The electron shock surfing acceleration is an effective mechanism for accelerating the particles toward the relativistic regime even in two dimensions with a large mass ratio. Buneman instability excited at the leading edge of the foot in the super-high Mach number shock results in a coherent electrostatic potential structure. While multi-dimensionality allows the electrons to escape from the trapping region, they can interact with the strong electrostatic field several times. Simulation runs in various parameter regimes indicate that the electron shock surfing acceleration is an effective mechanism for producing relativistic particles in extremely high Mach number shocks in supernova remnants, provided that the upstream electron temperature is reasonably low.