Recent theoretical results on the stability of FRCs to the internal tilt mode are presented. An approximate treatment of collisions shows that collisions have a small effect on the growth rate of the mode until the plasma becomes very collisional (lambda/sub ii/ less than or equal to r/sub s/2). Finite Larmor radius theory predicts that the growth rate of the instability normalized to that of MHD depends only on the combination anti s/e, where e is the plasma elongation. However, a full Vlasov stability calculation does not appear to show such a scaling
