Measurements of DT alpha particle loss near the outer midplane of TFTR

Abstract

Measurements of DT alpha particle loss to the outer midplane region of TFTR have been made using a radially movable scintillator detector. The conclusion from this data is that mechanisms determining the DT alpha loss to the outer midplane are not substantially different from those for DD fusion products. Some of these results are compared with a simplified theoretical model for TF ripple induced alpha loss, which is expected to be the dominant classical alpha loss mechanism near the outer midplane. An example is given of plasma driven MHD induced alpha particle loss to the outer midplane, but no sign of any `collective` alpha instability induced alpha particle loss has yet been observed at this location