Ion-scale spectral break in turbulent plasmas with low-β_i

The magnetic energy spectrum observed in the solar wind displays at the hydrodynamic scale a power-law behavior consistent with Alfvén turbulence. The transition from Alfvén to kinetic Alfvén turbulence predicts a break in the power law at the ion gyroscale if β_e ~ β_i >> 1, and at the ion acoustic scale if β_i << β_e << 1. The first case is consistent with observations, but in the second case, the available observations favor the ion inertial scale.

In this presentation, we examine the turbulent regime with β_i << β_e << 1 using numerical simulations run with kinetic/fluid hybrid particle-in-cell code Hybrid-VPIC, and we investigate the location of the spectral break and study what physical effects may be responsible for it.