Studies of whistler and lower hybrid drift waves during asymmetric reconnection in space and laboratory plasmas

Generation and propagation of whistler and lower-hybrid drift wave (LHDW) are studied with data from the Magnetospheric Multiscale (MMS) and the Magnetic Reconnection Experiment (MRX). In particular, the dispersion relation of the whistler mode near the magnetospheric (low-density) separatrix is measured for the first time by using correlations between four MMS satellites. The measured dispersion relation shows that the whistler wave propagates nearly parallel to the magnetic field, which is consistent with a linear analysis. The linear analysis also confirms that the whistler wave is generated by temperature anisotropy in the electron tail population. The temperature anisotropy is likely caused by the loss of electrons with a high velocity parallel to the magnetic field to the exhaust region. A statistical analysis of MRX data shows a positive correlation between whistler and lower-hybrid drift instability (LHDI) activities, indicating LHDI may contribute to the loss of electrons with a high parallel velocity. We have also observed in both laboratory and space plasmas that LHDW is excited inside the current sheet during reconnection with a sizable guide field. LHDW propagates obliquely to the magnetic field. The excitation mechanism of LHDW is discussed via analysis of MRX and MMS data and a linear calculation. Preliminary results show that LHDW induces density fluctuations that are in phase with electric field fluctuations, potentially causing anomalous resistivity and electron heating in the current sheet. This work is supported by DOE Contract No. DE-AC0209CH11466.