Role of electron inertia in nonlinear electron magnetohydrodynamics.

This paper reports experimental investigations of nonlinear electron magnetohydrodynamic (EMHD) structures of the size of skin depth. It is shown that the difficulty of exciting EMHD structures with k[SUB⊥]d[SUBe] ∼ 1 is not related to any specifics of antenna-plasma coupling mechanisms but to a general attenuation scaling with antenna size. Formation of null-point or mirror geometry with contribution from antenna current leads to nonlinear effects in case of EMHD structures with k[SUB⊥]d[SUBe] ≪; 1. However, there is weakening of nonlinearity in case of k[SUB⊥]d[SUBe] ∼ 1. Observations indicate that reconnection rates in EMHD may not be independent of the plasma skin depth, in contrast to theoretical predictions. It is pointed out that electron inertia takes the role of magnetic field in the region where adiabatic constants of motion do not remain constant. [ABSTRACT FROM AUTHOR]