DIII-D RESEARCH OPPORTUNITIES FORUM FOR THE 2013 EXPERIMENTAL CAMPAIGN Review | Direct submission with log-in | Request submission without log-in
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Title	312: Limits to pedestal radiation high beta discharges
Name:	Anthony Leonard leonard@fusion.gat.com	Affiliation:	General Atomics
Research Area:	Steady State Heating and Current Drive	Presentation time:	Not requested
Co-Author(s):		ITPA Joint Experiment :	No
Description:	Document the limits to pedestal/mantle radiation for heat flux control in high beta discharges	ITER IO Urgent Research Task :	No
Experimental Approach/Plan:	Set up high beta discharge currently under study as candidate for FNSF/DEMO. Inject neon or argon for mantle radiation. Use radiated power feedback to control the radiation level. On a shot to shot basis increase the pedestal radiation level until significant degradation of the pedestal and confinement. The primary issue is how much power above the LH threshold must cross the separatrix in order to maintain confinement. Other issues could include the effect of increased Zeff and collisionality on the operational regime.
Background:	FNSF and DEMO scenarios for handling divertor heat flux rely on radiating as much power as possible inside the separatrix. A radiating mantle could this, but it is uncertain how much power can be radiated before the pedestal degrades, affecting confinement. It is generally thought that 1.5xP_LH needs to cross the separatrix, but little data exists to support this. Additionally, the addition of radiating species, such as neon or argon, could have additional effects, including Zeff and collisionality. How this will affect high beta scenarios is also not known.
Resource Requirements:	Radiated power control of neon or argon puffing
Diagnostic Requirements:	Bolometer feedback into the PCS
Analysis Requirements:
Other Requirements: