1997/10/13 by Eliot Quataert · 7 citations
Physics and Astronomy · #Accretion (finance) #Alfvén wave #Astrophysical Phenomena and Observations #Astrophysics and Cosmic Phenomena #Cyclotron #Dissipation #Energy cascade #Gyrokinetics #Gyroradius #Magnetohydrodynamics #Plasma #Solar and Space Plasma Dynamics #Turbulence #astro-ph
paper · pdf · doi:10.1086/305770
35 pages (Latex), 4 Figures. Submitted to ApJ
arxiv created 1997/10/13 · openalex publication_date 1998/06/20 · arxiv updated 2009/12/01 · openalex created_date 2016/06/24 · openalex updated_date 2026/08/05
Recent work on Alfvénic turbulence by Goldreich & Sridhar (GS) suggests that the energy cascades almost entirely perpendicular to the local magnetic field. As a result, the cyclotron resonance is unimportant in dissipating the turbulent energy. Motivated by the GS cascade, we calculate the linear collisionless dissipation of Alfvén waves with frequencies much less than the proton cyclotron frequency, but with perpendicular wavelengths of order the Larmor radius of thermal protons. In plasmas appropriate to hot accretion flows (proton temperature much greater than electron temperature), the dissipated Alfvén wave energy primarily heats the protons. For a plasma with β ≲ 5, however, where β is the ratio of the gas pressure to the magnetic pressure, the MHD assumptions utilized in the GS analysis break down before most of the energy in Alfvén waves is dissipated; how the cascade then proceeds is unclear. Hot accretion flows, such as advection-dominated accretion flows (ADAFs), are expected to contain significant levels of MHD turbulence. This work suggests that, for β ≳ 5, the Alfvénic component of such turbulence primarily heats the protons. Significant proton heating is required for the viability of ADAF models. We contrast our results on particle heating in ADAFs with recent work by Bisnovatyi-Kogan & Lovelace.