DIII-D RESEARCH OPPORTUNITIES FORUM FOR THE 2013 EXPERIMENTAL CAMPAIGN Review | Direct submission with log-in | Request submission without log-in
Print this page

Print this page
Title	168: Influence of the delay time between multiple massive gas injections at different toroidal locations
Name:	Nicolas Commaux commaux@fusion.gat.com	Affiliation:	Oak Ridge National Lab
Research Area:	Disruption Mitigation	Presentation time:	Not requested
Co-Author(s):	L. Baylor, E. Hollmann, D. Humphreys, P. Parks, N. Eidietis, J. Wesley, V. Izzo	ITPA Joint Experiment :	No
Description:	Determine the effect of the delay between multiple injections using the new MGI array at 135R-2 and the existing MEDUSA array at 15R+1 by doing a delay scan between the 2 systems. This scan was previously done on Cmod but the system on DIII-D would have a significantly different disposition (1/1 vs 1/2 on Cmod). The bolometer arrays and IR cameras would provide valuable data on the magnitude of the radiation asymmetry as a function of the delay.	ITER IO Urgent Research Task :	Yes
Experimental Approach/Plan:	Inject 2 MGI pulses using the 2 MGI arrays with a set delay time between the 2 in a regular H mode discharge and scan that delay time between the 2 injections to determine what is the evolution of the IR footprint and radiation asymmetries.
Background:	Radiation asymmetries induced by massive particle injection is a major concern for ITER. These asymmetries could induce local melting of the first wall if the toroidal radiation peaking factor reach a certain value. Injections at multiple toroidal locations are expected to mitigate this effect because it is assumed that the radiation asymmetry is due to the injection asymmetry. But recent results obtained C-mod tend to show the opposite: simultaneous injections on C-mod at 2 opposite toroidal locations induce a significantly stronger asymmetry (during the thermal quench) than one single injection. Simulations on C-mod show that this could be due to a strong n=1 mode growing and locking during the thermal quench. The phase of that mode with respect to an injection site being critical. But these results on C-mod were obtained using a 1/2 injection symmetry. Which might force the n=1 mode to right in front of an injection site (worst case scenario). The system on DIII-D will be a 1/1 symmetry which might prevent that effect and mitigate the asymmetries.
Resource Requirements:	Both MGI arrays. Regular tokamak systems. Good beams availability.
Diagnostic Requirements:
Analysis Requirements:
Other Requirements: