Analytical and computational studies of the effect of the By-field on the phenomena of cuurent disruption during substorms are proposed. Such a study is warranted by observations of the presence of By in the quiescent as well as the active magnetotail. Recently, we have shown that in the presence of By, the electron tearing mode can be destabilized ?X. Wang, A. Bhattacharjee and A.T.Y. Lui, J. Geophys. Res., 95, 15,047, 1990; attached as Appendix.!. We propose to extend our present work by means of analytical theory as well as particle simulation in the three- dimensional tail, and compare the predictions of theory with the AMPTE/CCE database. The specific tasks proposed are: (i) Unified analytical theory of electron and ion tearing in the presence of By, (ii) Particle simulation in a three-dimensional plasma sheet, (iii) Analytical nonlinear mode-coupling theory and predictions of particle acceleration, and (iv) comparison of theory with observations from AMPTE/CCE.
