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An Isaac Newton Institute Workshop

Reconnection in the Sun and Magnetosphere (Hewlett-Packard and Spitalfields Days)

Parameter study of ion acoustic resitivity in collisionless plasmas

Authors: Clare E. J. Watt (University of Alberta), Panagiota Petkaki (British Antarctic Survey), Richard B. Horne (British Antarctic Survey), Mervyn P. Freeman (British Antarctic Survey)


In order for magnetic reconnection to proceed, there must be some mechanism which can violate the ideal MHD condition in the diffusion region and allow plasma to diffuse across the magnetic field. One of the candidates for breaking the ideal MHD condition is resistivity or anomalous transport due to wave-particle interactions between unstable waves and the ambient plasma. We propose that in the presence of strong currents, ion-acoustic waves will be driven unstable and can provide significant values of resistivity. We present results from a parameter study of the resistivity due to this instability, concentrating on similar ion and electron temperature ratios. This parameter regime is difficult to study analytically, and so we use self-consistent Vlasov simulations to study the plasma response to the ion-acoustic instability. Our results show that the resistivity is very strongly dependent on the current present to drive the waves unstable.