Electrostatic precession of electron layers. Part II: Precession of finite length E layers

The precessional stability of un-neutralized, finite-length E layers is examined both theoretically and experimentally. The theoretical analysis assumes the layer is a rigid cylindrical thin shell. Experimental measurements are consistent with the assumption of rigidity. It is shown that in the absence of a toroidal field, an un-neutralized layer is unstable for all amplitudes. This is in contrast with a neutralized layer, which is stable above a critical amplitude. However, the precessional mode is stabilized by the application of a toroidal field. Experimental measurements of the precession frequency show agreement with theory within a factor of two. The discrepancy is attributed to the finite thickness of the layer.