Pressure anisotropy and viscous heating in weakly collisional plasma turbulence

Pressure anisotropy can strongly influence the dynamics of weakly collisional, high-beta plasmas, but its effects are missed by standard magnetohydrodynamics (MHD). Small changes to magnetic-field strength generate large pressure-anisotropy forces, heating plasma, driving instabilities and rearranging flows, even on scales far above particles’ gyroscales where kinetic traditionally considered most important. Here, we study pressure turbulent plasmas threaded a mean magnetic field (Alfvénic turbulence). Extending previous results that were concerned with Braginskii MHD, consider wide range regimes parameters using simplified fluid model based drift kinetics heat fluxes calculated Landau-fluid closure. We show viscous (pressure-anisotropy) dissipates between quarter (in collisionless regimes) half collisional turbulent-cascade power injected at scales; this does not depend either plasma beta or ion-to-electron temperature ratio. This will in turn plasma's thermodynamics regulating energy partition different dissipation channels (e.g. electron ion heat). Due anisotropy's rapid dynamic feedback onto flows create it – an effect term ‘magneto-immutability’ is confined narrow near forcing scale, supporting nearly conservative, MHD-like inertial-range cascade, via which rest transferred small scales. Despite model, our including rate, distributions spectra compare favourably recent hybrid-kinetic simulations. promising for more general use extended-fluid (or MHD) approaches such as intracluster medium, hot accretion solar wind.