MHD fluctuations in ISX-B

Studies of beam-heated plasmas with Mirnov coils have been continued. Previous observations have shown no correlation between the (1;1) driven modes and confinement; however at higher frequencies, such a correlation can be found. A band-pass filter, monitoring frequencies approx. = 150 kHz, and the integrated fluctuation amplitude from the high-frequency wave-form data are used to obtain B/sub theta//B/sub theta/. The results show increasing B/sub theta//B/sub theta/ is associated with decreasing energy confinement for I/sub p/ and P/sub b/ scans and for cases with and without added neon (known to modify confinement). Using three coils at different toroidal locations, modes with n approx. = 15 have been found under certain conditions. A comparison of co-, counter-, and balanced beam discharges, in which toroidal rotation velocities were measured, allows an estimate of the n values monitored during the scans.