MHD induced alpha particle loss in TFTR

Increases in alpha particle loss due to MHD activity in TFTR were observed for both coherent modes and transient reconnection events using an array of scintillator detectors near the wall. The magnitude of the coherent MHD induced alpha loss was normally comparable to the MHD quiescent first orbit or TF ripple loss, but the magnitude of the alpha loss during reconnection events was up to 1000 times higher than this for a short time. Modelling suggests that the coherent MHD loss mechanism will be less significant for future reactor scale DT tokamaks due to the smaller ratio of the alpha gyroradius to the minor radius. (author)