Geophysical research letters vol:23 issue:14 pages:1713-1716
A comparison of full kinetic and hybrid simulations for T-e/T-i > 1, where T-e(T-i) is the electron (ion) temperature, indicates that contact discontinuities cannot persist in collisionless plasmas. A simple analysis suggests that the potential barrier to ion mass and thermal transport identified by Wu et al.  in their hybrid calculations can preserve the contact discontinuity if the contributions of electron thermal transport are small. When T-e/T-i > 1, electron energy transport in kinetic calculations results in large potentials which reduce the effectiveness of the potential barrier. Thus, contact discontinuities are unlikely to be observed in spacecraft observations.