title: Acceleration of particles in imbalanced magnetohydrodynamic turbulence.
abstract: The present work investigates the acceleration of test particles, relevant to the solar-wind problem, in balanced and imbalanced magnetohydrodynamic turbulence (terms referring here to turbulent states possessing zero and nonzero cross helicity, respectively). These turbulent states, obtained numerically by prescribing the injection rates for the ideal invariants, are evolved dynamically with the particles. While the energy spectrum for balanced and imbalanced states is known, the impact made on particle heating is a matter of debate, with different considerations giving different results. By performing direct numerical simulations, resonant and nonresonant particle accelerations are automatically considered and the correct turbulent phases are taken into account. For imbalanced turbulence, it is found that the acceleration rate of charged particles is reduced and the heating rate diminished. This behavior is independent of the particle gyroradius, although particles that have a stronger adiabatic motion (smaller gyroradius) tend to experience a larger heating.
authors.affiliation: Applied Mathematics Research Centre, Coventry University, Coventry CV1 5FB, United Kingdom and Max-Planck/Princeton Center for Plasma Physics and Max-Planck-Institut für Plasmaphysik, D-85748 Garching, Germany and Max Planck Institut für Sonnensystemforschung, Justus-von-Liebig-Weg 3, D-37077, Göttingen, Germany.
authors.forename: Bogdan
authors.initials: B
authors.lastname: Teaca
authors.affiliation: Max-Planck/Princeton Center for Plasma Physics and Max-Planck-Institut für Plasmaphysik, D-85748 Garching, Germany.
authors.forename: Martin S
authors.initials: MS
authors.lastname: Weidl
authors.affiliation: Max-Planck/Princeton Center for Plasma Physics and Max-Planck-Institut für Plasmaphysik, D-85748 Garching, Germany.
authors.forename: Frank
authors.initials: F
authors.lastname: Jenko
authors.affiliation: Institut für Theoretische Physik, Lehrstuhl IV: Weltraum- und Astrophysik, Ruhr-Universität Bochum, D-44780 Bochum, Germany.
authors.forename: Reinhard
authors.initials: R
authors.lastname: Schlickeiser
mesh_terms: D003198:Computer Simulation; D057446:Hydrodynamics; D007700:Kinetics; D060526:Magnetic Fields; D009038:Motion