源粒子动量分布对激波中费米加速的影响

在不同源粒子动量分布和不同参数的情况下,本文计算了受到激波费米加速的荷电粒子的随时间演化的能谱.计算结果表明:不论源粒子的动量分布如何,当时间足够长时,被加速粒子的能谱的高能部分为幂律谱;但是,被加速粒子的能谱的时间演化过程,则与源粒子的动量分布有关.所以,在短暂的激波过程中,用一个谱指数不变的幂律谱表示被加速粒子能谱的通常做法是不合适的. 

The Influence of Momentum Distribution of Source Particles on Fermi Accleration in Shock Waves

The time dependent energy spectra of acclerated particles in Fermi accleration by shock waves have been calculated for various momentum distributions of source particles and parameters. It is shown that the high energy parts of acclerated particles spectra are power-law forms in the enough long time, no matter what the momentum distribution is possessed by source particles. But the time evolution of energy spectrum of acclerated particles depends on the momentum distribution of source particles. Therefore it is unsuitable for a transient shock process that the energy spectra of acclerated particles are represented by power-law form with constant index.