Speaker
Description
Turbulence is ubiquitous throughout different space plasma environments, facilitating the cascade of energy down to smaller and smaller length scales. That said, the different parameter regimes at which these plasmas exist have a significant effect on the way the cascade develops- turbulence at the MHD limit will not have the same attributes as turbulence at the kinetic limit. For instance, kinetic fluctuations are compressive and much more liable to Landau damping than those at the MHD-scale, but despite this the kinetic solar wind turbulent cascade is well-documented. Though in-situ measurements can provide a wealth of knowledge about the properties of space turbulence, they are limited by their spatial extent relative to the plasma environment and their reproducibility. Laboratory plasmas can provide insight complementary to satellite data; this has already been the case with several experiments run on the LArge Plasma Device (LAPD) at the University of California-Los Angeles. The space plasma turbulence group at Queen Mary University of London (QMUL) has run Alfvén wave experiments on LAPD studying weak and strong interactions at a range of $k_{\perp} \rho_s$ values, from negligibly small up to order unity. The change in the properties of the drive waves and their interaction products between these limits has been quantified via detailed measurements of magnetic and electric field fluctuations in multiple different counter-propagating wave configurations. Further data runs driven over a range of power inputs allow for an analysis of the residual energy- and cross helicity-dependent properties of the interactions. With this experimental setup, the fundamental physics of the three-wave interaction can be studied in detail while minimizing the impact of other solar wind phenomena. Also being presented at this meeting are results from previous complementary QMUL-group experiments, which showed novel nonlinear interactions in the traditionally MHD regime.
