Alfvenic tornadoes

Abstract

It is shown that a three-dimensional (3D) modified-kinetic Alfvén waves (m-KAWs) can propagate in the form of Alfvénic tornadoes characterized by plasma density whirls or magnetic flux ropes carrying orbital angular momentum (OAM). By using the two fluid model, together with Ampère's law, we derive the wave equation for a 3D m-KAWs in a magnetoplasma with $m_e/m_i \ll β\ll 1$, where $m_e$ $(m_i)$ is the electron (ion) mass, $β=4 πn_0 k_B (T_e + T_i)/B_0^2$, $n_0$ the unperturbed plasma number density, $k_B$ the Boltzmann constant, $T_e (T_e)$ the electron (ion) temperature, and $B_0$ the strength of the ambient magnetic field. The 3D m-KAW equation admits solutions in the form of a Laguerre-Gauss (LG) Alfvénic vortex beam or Alfvénic tornadoes with plasma density whirls that support the dynamics of Alfvén magnetic flux ropes.

13 pages