High βN pulses with the ILW develop MHD instabilities after 2-3 s of NBI heating; presently, pulses with MHD-free duration in excess of 5 s only exist at βN < 2. Short durations at βN > 3, with the ILW, appear to be caused by intrinsically less stable profiles, in fact sawtooth triggers seldom occur in this range. It is important to remark that, rather than to MHD onset, the systematic lack of long high power pulses with the ILW was due to heat load and impurity problems. Improved impurity control should also lead back towards the previous JET-C stability conditions.
MHD in JET hybrid plasmas with the ITER Like Wall
Pucella, G.;Giovannozzi, E.;Frigione, D.;Buratti, P.
2015-01-01
Abstract
High βN pulses with the ILW develop MHD instabilities after 2-3 s of NBI heating; presently, pulses with MHD-free duration in excess of 5 s only exist at βN < 2. Short durations at βN > 3, with the ILW, appear to be caused by intrinsically less stable profiles, in fact sawtooth triggers seldom occur in this range. It is important to remark that, rather than to MHD onset, the systematic lack of long high power pulses with the ILW was due to heat load and impurity problems. Improved impurity control should also lead back towards the previous JET-C stability conditions.File in questo prodotto:
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