Excitation and propagation of whistler and lower-hybrid drift waves during reconnection in space and laboratory plasmas*

Magnetic reconnection plays an important role in explosive phenomena in magnetized plasmas such as solar flares and substorms. Various waves and instabilities can be generated during reconnection and make a significant impact on the reconnection dynamics. Here, whistler and lower-hybrid waves during reconnection are studied with data from the Magnetospheric Multiscale (MMS) mission 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. 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 caused by the loss of electrons with a high velocity parallel to the magnetic field to the exhaust region. The correlative behavior of the whistler wave and the lower-hybrid drift instability (LHDI) suggests that LHDI is responsible for the enhanced transport of high parallel velocity electrons to the exhaust. A statistical analysis of MRX data shows a positive correlation between whistler and LHDI activities. Finally, we have observed in both laboratory and space plasmas that the lower-hybrid drift wave (LHDW) is excited inside the current sheet during reconnection with a sizable guide field. LHDW propagates obliquely to the magnetic field. Moreover, LHDW induces density fluctuations that are in phase with electric field fluctuations. The excitation mechanism of LHDW is discussed via analysis of MRX and MMS data and a linear calculation. Initial results indicate that LHDW contributes to anomalous resistivity and electron heating in the current sheet.