MIDPLANE MEASUREMENTS OF MEV ION CONFINEMENT IN TFTR

A new detector has been designed and installed on TFTR for studying the confinement of MeV ions, especially for measuring the losses due to the toroidal field ripple. It is located just below the outer midplane where the peak in ripple-induced losses is expected. The detector consists of a scintillator [ZnS(Ag)] and collimating apertures mounted on a radially movable probe. New design features of this detector are presented along with some of the first results.