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We herein investigate shock formation and particle acceleration processes forboth protons and electrons in a quasi-parallel high-Mach-number collisionlessshock through a long-term, large-scale particle-in-cell simulation. We showthat both protons and electrons are accelerated in the shock and that theseaccelerated particles generate large-amplitude Alfv\'{e}nic waves in theupstream region of the shock. After the upstream waves have grown sufficiently,the local structure of the collisionless shock becomes substantially similar tothat of a quasi-perpendicular shock due to the large transverse magnetic fieldof the waves. A fraction of protons are accelerated in the shock with apower-law-like energy distribution. The rate of proton injection to theacceleration process is approximately constant, and in the injection process,the phase-trapping mechanism for the protons by the upstream waves can play animportant role. The dominant acceleration process is a Fermi-like processthrough repeated shock crossings of the protons. This process is a `fast'process in the sense that the time required for most of the accelerated protonsto complete one cycle of the acceleration process is much shorter than thediffusion time. A fraction of the electrons is also accelerated by the samemechanism, and have a power-law-like energy distribution. However, theinjection does not enter a steady state during the simulation, which may berelated to the intermittent activity of the upstream waves. Upstream of theshock, a fraction of the electrons is pre-accelerated before reaching theshock, which may contribute to steady electron injection at a later time.

Particle acceleration and wave excitation in quasi-parallel high-Mach-number collisionless shocks: Particle-in-cell simulation