DESTABILIZATION OF STRONGLY MAGNETIZED JETS

Simulations of strongly magnetized slab jets in uniform expansion in a n external atmosphere have been performed and compared to an unmagneti zed expanding slab jet. A strongly magnetized super-Alfvenic jet with lower magnetosonic Mach number but with sonic Mach number equal to a p urely fluid jet destabilizes in a much shorter distance than the fluid jet. A strongly magnetized sub-Alfvenic jet remains stable until the jet becomes super-Alfvenic. At the Alfven point the jet is submagnetos onic and destabilizes abruptly. Results from a spatial stability analy sis of the magnetized slab jet are compared to the numerical simulatio ns. In general, predictions based on the theory are borne out by the s imulations. In particular, the stability properties of a super-Alfveni c jet are confirmed to be a function of the magnetosonic Mach number, and the theoretical prediction of rapid jet destabilization at the Alf ven point transition between sub-Alfvenic and super-Alfvenic flow is c onfirmed. However, nonlinear effects associated with decreasing the je t density relative to the external density and with increasing the mag netic field strength can increase the destabilization-decollimation le ngth and reduce decollimation, respectively. Some of the implications for three-dimensional jets are considered.