Anomalous resistivity in non‐Maxwellian plasmas

Abstract

Vlasov simulations of the current‐driven ion‐acoustic instability produced in Maxwellian and non‐Maxwellian (Lorentzian, κ = 2) electron‐ion plasma with number density 7 × 106 cm−3, reduced mass ratio mi/me = 25, and electron to ion temperature ratio Te/Ti = 1 are presented and compared. A concise stability analysis of current‐driven ion‐acoustic waves in Maxwellian and non‐Maxwellian plasmas modeled by generalized Lorentzian distribution function with index 2 ≤ κ ≤ 7 and electron to ion temperature ratio 1 ≤ Te/Ti ≤ 100 is also presented. The ion‐acoustic instability is excited in low temperature ratio Lorentzian (κ = 2) plasma for lower absolute electron drift velocity (up to half the critical electron drift velocity of a Maxwellian). The anomalous resistivity resulting from ion acoustic waves in a Lorentzian plasma is a strong function of the electron drift velocity and in the work presented here varies by a factor of ∼100 for a 1.5 increase in the electron drift velocity. Furthermore, ion‐acoustic anomalous resistivity is excited for electron drift velocities that would be stable for Maxwellian plasmas. The magnitude of resistivity which can be generated by unstable ion‐acoustic waves may be important for magnetic reconnection at the magnetopause.