Relativistic particle acceleration in developing Alfvén turbulence

A new particle acceleration process in a developing Alfvén turbulence in the course of successive parametric instabilities of a relativistic pair plasma is investigated by utilizing one-dimensional electromagnetic full particle code. Coherent wave-particle interactions result in efficient particle acceleration leading to a power-law-like energy distribution function. In the simulation, high-energy particles having large relativistic masses are preferentially accelerated as the turbulence spectrum evolves in time. The main acceleration mechanism is simultaneous relativistic resonance between a particle and two different waves. An analytical expression of maximum attainable energy in such wave-particle interactions is derived.