Resonant helical divertor experiments in ohmic and auxiliary heated JIPP T-IIU plasmas

A series of initial resonant helical divertor (RHD) experiments have been carried out in ohmically and auxiliary heated JIPP T-IIU plasmas. Disruptive and MHD instabilities make the interpretation of the RHD results difficult but an apparent increase in the energy confinement time is observed when the helical magnetic perturbation is applied. This may be due to the suppression of MHD activity or to a reduction in the edge convective heat losses. Magnetic island effects have been observed on the floating potential of a Langmuir probe array and energy scrape off layer widths have been measured with and without helical perturbations during ICRF operation. Basic pump limiter data are presented including ion temperatures and C+4 impurity profiles. Energy confinement times are reported in ohmically and NBI heated discharges. 5 refs., 7 figs