CHARACTERIZATION OF ALPHA-PARTICLE LOSS DURING DISRUPTIONS IN TFTR DURING DEUTERIUM-TRITIUM OPERATION

The timing of alpha losses, with respect to the various phases of a di sruption, and the impact location of the losses are characterized duri ng high fusion power operation of TFTR with deuterium and tritium fuel s. Characterization of alpha losses is important for the design of fut ure fusion devices such as ITER. In addition, characterization of the alpha losses with respect to the disruption evolution helps in the und erstanding of the dynamics of the disruption process and related MHD e vents such as sawtooth crashes. Disruptions are characterized as havin g several standard phases, applicable to most disruptions in all tokam aks: precursor, thermal quench(es) and current quench. Most of the los ses are observed to occur during the thermal quench phase(s). In high beta disruptions, alpha losses start abruptly during the growth of MHD precursors, just before the onset of the thermal quench. The initial burst of losses, lasting as little as 100 mu s, can release a signific ant fraction (one third) of the total disruption induced losses during the thermal quench. An inventory of alpha particles suggests that the alpha loss distribution during disruptions might be quite different f rom that expected during non-disruptive discharges. There are no obvio us differences between fast fusion product losses during deuterium-deu terium (DD) and deuterium-tritium (DT) disruptions, aside from the lar ge alpha loss component in DT discharges.