Authors: Mel Abler (Space Science Institute & UCLA), Seth Dorfman (Space Science Institute), Alfred Mallet (SSL), Christopher Chen (Queen Mary University of London), Trevor Bowen (SSL)

Alfvénic fluctuations – fluctuations with magnetic-field and velocity fluctuations perpendicular to the background magnetic field which are proportional to each other – are thought to be ubiquitous in magnetized astrophysical plasma environments and are observed across scales in our own solar wind. Recent theoretical work by Mallet et al [1] proposes a mechanism by which small-scale, oblique Alfvén waves undergo a one-dimensional nonlinear steepening process only at dispersive length scales smaller than the ion inertial length (e.g. when one or more of k⊥ρs, k⊥de, or k∥di becomes significant). This work presents the first laboratory tests of this steepening model, comparing predictions for the amplitude of the harmonic of a driven wave to experimental measurements from the Large Plasma Device (LAPD). These tests span highly inertial (vA ≫ vth,e) to highly kinetic (vA ≪ vth,e) conditions at low β to provide insight into turbulence in environments like the solar corona, where the usual counterpropagating Alfvén wave interactions may be suppressed.

 

[1] Mallet, Alfred, et al. “Nonlinear dynamics of small-scale Alfvén waves.” Physics of Plasmas 30.11 (2023).

 

Funded by DE-SC0023326.