Sawtooth mechanism of particle acceleration at shocks in random magnetic fields

Abstract

Since there is a discontinuity in the magnetic field and plasma speed at the shock in a space plasma, the charged particles that pass the shock are accelerated and gain energy. The charged particles are known to move mainly along magnetic field lines. If the magnetic field line crosses the shock many times like a sawtooth, the particles that follow the magnetic field lines can cross the shock many times. The diffusion in pitch angle can cause the particles to encounter the shock several times at each magnetic field-shock crossing. The statistics of the magnetic field-shock crossings can be used to develop the sawtooth mechanism of particle acceleration, including the resulting particle spectrum.