2025/05/14 by Pratik Patel, Sharad Kumar Yadav, Patel, Pratik +5
Physics and Astronomy · #FOS: Physical sciences #Magnetic confinement fusion research #Plasma Physics (physics.plasm-ph) #Space Physics (physics.space-ph)
paper · pdf · doi:10.48550/arxiv.2505.09537
openalex publication_date 2025/05/14 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/28
We carry out extensive pseudospectral direct numerical simulations (DNSs) of decaying three-dimensional (3D) Hall magnetohydrodynamics (3D HMHD) plasma turbulence at three magnetic Prandtl numbers Prm=0.1, 1.0 and 10.0. Our DNSs have been designed to uncover the dependence of the statistical properties of 3D HMHD turbulence on Prm and to bring out the subtle interplay between three lengths, the kinetic and magnetic dissipation length scales ηu, and ηb and the ion-inertial scale di, below which we see the manifestations of the Hall term. This interplay, qualitatively apparent from isosurface plots of the moduli of the vorticity and the current density, is exposed clearly by the kinetic-energy and magnetic-energy spectra, Eu(k) and Eb(k), respectively. We find two different inertial regions, In the first inertial region k ki, the scaling of Eb(k) depends upon PrM: At Prm=0.1, the spectral-scaling exponent is -17/3, but for Prm=1 and 10 this exponent is -11/3. We then show theoretically that Eu(k) ∼ k2 Eb(k) for Prm ≪ 1 and Eb(k) ∼ k2 Eu(k) for Prm ≫ 1; our DNS results are consistent with our theoretical predictions. We examine, furthermore, left- and right-polarised fluctuations of the fields that lead, respectively, to the dominance of ion-cyclotron or whistler waves.