Radial structure of instability modes in the EBT hot electron annulus

In the ELMO Bumpy Torus (EBT) device, a hot electron annulus is present near the outside edge of a warm core plasma. Although this provides a localized minimum in B and stabilizes low beta interchange modes of the core plasma, a number of instabilities may still persist in such a configuration. These are: the hot electron interchange mode, the coupling of the ring with compressional Alfven waves of the core plasma, core plasma pressure-driven modes, and instabilities present in the cold surface plasma region outside the ring. The radial structure of such modes is of interest because both instabilities localized to the ring region and those extending into the core plasma can be present in the appropriate parameter regions. Also, studies of the radial structure are useful in assessing the importance of effects such as finite k/sub perpendicular/rho/sub i/ and k/sub perpendicular/ rho/sub H/ that are not included in the present theory. Radially resolved calculations have been done for a z-pinch model which corresponds to a bumpless, azimuthally symmetric version of EBT. A shooting method is employed that matches derivatives of the eigenfunction near the center of the annulus. Relativistic effects are included and a variety of boundary conditions and core and hot electron models have been considered. Results are discussed for the various modes that are present