Relativistic Turning Acceleration of Resonant Electrons by Coherent Whistler-Mode Waves in a Dipole Magnetic Field(RECENT RESEARCH ACTIVITIES)

Relativistic Turning Acceleration of Resonant Electrons by Coherent Whistler-Mode Waves in a Dipole Magnetic Field(RECENT RESEARCH ACTIVITIES)
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DOI：
10.1029/2006ja012243
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发表时间：
2007-06
期刊：
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影响因子：
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通讯作者：
Y. Omura;D. Summers;H. Usui
Y. Omura;D. Summers;H. Usui
中科院分区：
其他
文献类型：
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作者：
Y. Omura;D. Summers;H. Usui

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[1]我们报道了一种通过地球偶极磁场中的相干哨声模波来加速高能电子的非常有效的过程，我们在最近的测试粒子模拟中发现了这一过程。对于几百千电子伏特的弱相对论种子电子，有效的加速过程发生了。假设哨声波包在内磁层赤道面附近被激发，并在远离赤道的地方传播，加速过程是不可逆的。在一个足够长的S数量级的哨声模波包中，高能电子通过单次共振俘获过程被加速到几兆电子伏特的相对论能量范围。我们称这种特殊的加速过程为相对论转向加速(RTA)，这可能是增加外辐射带中相对论电子通量的一种可行机制。RTA的必要条件是哨声模波的幅度相对较大，范围在50到几百皮特斯拉之间，以及俘获电子的初始动能在几百千电子伏特的能量范围内。对RTA过程加速的电子的最小能量和所获得的最大能量进行了解析推导，并用实验粒子模拟进行了验证。
[1] We report a very efficient process for accelerating high-energy electrons by coherent whistler mode waves in the Earth's dipole magnetic field, which we have found in our recent test particle simulations. The efficient acceleration process takes place for weakly relativistic seed electrons of a few hundred kiloelectronvolts. Under an assumption that the whistler mode wave packets are excited near the equatorial plane of the inner magnetosphere and propagate away from the equator, the acceleration process becomes irreversible. With a sufficiently long whistler mode wave packet of the order of 1 s, the energetic electrons are accelerated to a relativistic energy range of a few megaelectronvolts through a single resonant trapping process. We call this particular acceleration process relativistic turning acceleration (RTA), which could be a viable mechanism for increasing relativistic electron fluxes in the outer radiation belt. Necessary conditions for RTA are a relatively large amplitude of whistler mode waves, in the range of 50 to a few hundred picoteslas, and an initial kinetic energy of trapped electrons in the energy range of a few hundred kiloelectronvolts. The minimum energy of electrons accelerated by the RTA process and the maximum energy attained by it are derived analytically and verified by the test particle simulations.