Spectral Cascade and Energy Dissipation in Kinetic Alfven Wave Turbulence

Spectral cascade and energy dissipation of Alfven turbulence is studied using a massively parallel gyrokinetic particle simulation. The simulation observes a magnetic energy spectrum with a power law index of ”-5/3 ” in the long wavelength, which agrees with magnetohydrodynamic results in the inertial range. In the dissipation range, the simulation finds a spectral break point on the ion gyroradius scale, followed by a steepening of the spectrum, a depletion of the spectral energy, and a decoupling of electric and magnetic spectra at an even shorter scale. Simulation results agree well with space plasma observation data and suggest that the dissipation of kinetic Alfven wave is a plausible mechanism for collisionless plasma heating. 1