3 research outputs found
Magnetic Helicity Conservation and Inverse Energy Cascade in Electron Magnetohydrodynamic Wave Packets
Electron magnetohydrodynamics (EMHD) provides a fluid-like description of
small-scale magnetized plasmas. An EMHD wave (also known as whistler wave)
propagates along magnetic field lines. The direction of propagation can be
either parallel or anti-parallel to the magnetic field lines. We numerically
study propagation of 3-dimensional (3D) EMHD wave packets moving in one
direction. We obtain two major results: 1. Unlike its magnetohydrodynamic (MHD)
counterpart, an EMHD wave packet is dispersive. Because of this, EMHD wave
packets traveling in one direction create opposite traveling wave packets via
self-interaction and cascade energy to smaller scales. 2. EMHD wave packets
traveling in one direction clearly exhibit inverse energy cascade. We find that
the latter is due to conservation of magnetic helicity. We compare inverse
energy cascade in 3D EMHD turbulence and 2-dimensional (2D) hydrodynamic
turbulence.Comment: Phys. Rev. Lett., accepted (4pages, 4 figures