Laboratory Characterization of a Novel Hall-Driven Alfvén Wave Interaction as an Energy Transfer Mechanism in Imbalanced Turbulence

Imbalanced plasma turbulence (turbulence with a much higher flux of fluctuations traveling in one direction than another) is a fundamental process which occurs throughout the universe, including many regions of the solar wind. The ubiquity of imbalanced plasma turbulence makes understanding the underlying nonlinear interactions critical to our understanding of energy transfer across scales throughout the heliosphere. We present laboratory measurements from the Large Plasma Device (LAPD) of a novel Hall-driven interaction between co-propagating Alfvén waves [1] and show that the amplitude of the lowest order nonlinearly produced modes are consistent with theoretical predictions; we then further compare these mode amplitudes to prior measurements of modes nonlinearly generated by the standard MHD counter-propagating interaction and a Hall-driven wave steepening process to study the relative importance of each process for energy transfer at ion scales in a highly imbalanced regime.

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