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Title	113: Heat Load during slow current quench phase of disruptions/VDEs and its relation with poloidal halo c
Name:	Alberto Loarte-Prieto Alberto.Loarte@iter.org	Affiliation:	ITER Organization
Research Area:	Disruption Mitigation	Presentation time:	Requested
Co-Author(s):	M. Sugihara, E. Hollmann, R. Pitts, A. Loarte, V. Izzo, N. Eidietis, D. Humphreys	ITPA Joint Experiment :	No
Description:	Measure heat deposition due to particles together with halo current.	ITER IO Urgent Research Task :	Yes
Experimental Approach/Plan:	Set up fast diagnostics, especially IR cameras and wall probes, for accurate (total) heat load measurements. Set up also fast diagnostics for only radiation power deposition to derive the net heat load only due to particles. Simultaneously measure the halo current. It is ideal if plasma temperature can be directly measured, but if not, temperature should be estimated from the current quench rate. From these measurements, heat load associated with the halo current is to be derived. Create intentional downward hot VDEs and repeat to get shot-shot repeatibility. Create several different current quench (CQ) speeds, e.g., fast quench, slow quench and intermediate quench speed. In order to create different CQ speeds, a scan of the initial plasma thermal energy and a series of hot VDEs (no mitigation) and a series of mitigated VDEs by using different species of impurity and amount (from H2/D2 to Ne or Ar) for triggering thermal quench during vertical movement should be performed. It is expected that the halo current magnitude as well as the dissipated energy fraction by radiation and particles is very different for these different CQ speed discharges, which should make the derivation of the relation between the heat load and the halo current clearer and more reliable.
Background:	During the current quench phase of VDEs (center disruption case also), ITER plasma will have always strong contact with the wall/divertor. So far, ITER has assumed that radiation energy dissipation will dominate during this phase, so that no significant heat load has been specified. However, recent experiments in various machines, e.g., JET ILW, indicate that significant fraction of magnetic energy seems to be dissipated convectively and/or conductively. This indication is supported by the observed small radiation power during this phase, especially for slow current quench discharges. In ITER, melting of beryllium wall is a large concern, if heat load is localized to the upper and lower first wall region. Thus, following information is particularly important for the assessment of the impact of the heat load during CQ phase; (1) Width of the convective/conductive heat flux during CQ phase and their parameter dependence, (2) Relation of these heat flux width to the halo current width.
Resource Requirements:	1 run day. 6 beams, 4 gyrotrons.
Diagnostic Requirements:	IR fast cameras (aimed at lower divertor and at main chamber, if possible), fast visible cameras (aimed at main chamber to the extent possible), SPRED, SXR, interferometers, fast filterscopes, CER spectrometers, Tile current monitor and Rogowski loops for halo current measurement.
Analysis Requirements:	some analysis will be required to estimate plasma temperature and Zeff.
Other Requirements:	None