Thermal disequilibration of ions and electrons by collisionless plasma turbulence

• DOI: 10.1073/pnas.1812491116
• Publication Date: 2019-01-01T01:10:03Z
• Authors: Yohei Kawazura; Michael Barnes; Alexander A. Sche...
• Keywords: High Energy Astrophysical Phenomena (astro-ph.HE); FOS: Physical sciences; 7. Clean energy; 01 natural sciences; Physics - Plasma Physics; Space Physics (physics.space-ph); Plasma Physics (physics.plasm-ph); Physics - Space Physics; 13. Climate action; Physical Sciences; 0103 physical sciences; Astrophysics - High Energy Astrophysical Phenomena

Significance Large-scale astrophysical processes inject energy into turbulent motions and electromagnetic fields, which carry this energy to small scales and eventually thermalize it. How this energy is partitioned between ions and electrons is important both in plasma physics and in astrophysics. Here we determine this energy partition via gyrokinetic turbulence simulations and provide a simple prescription for the ion-to-electron heating ratio. We find that turbulence promotes disequilibration of the species: When magnetic energy density is greater than the thermal energy density, electrons are preferentially heated, whereas when it is smaller, ions are. This is a relatively rare example of nature promoting an ever more out-of-equilibrium state in an environment where particle collisions are not frequent enough to equalize the temperatures of the species.