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Title	24: Plasma response to 3D magnetic perturbations in the unfavorable grad-B drift direction
Name:	Devon Battaglia dbattagl@pppl.gov	Affiliation:	Princeton Plasma Physics Laboratory
Research Area:	ELM Control	Presentation time:	Requested
Co-Author(s):	Todd Evans	ITPA Joint Experiment :	No
Description:	The experiment will aim to characterize the plasma response to n=3 magnetic perturbations in a LSN plasma with the toroidal field reversed (unfavorable grad-B drift). A LSN shape is desired in order to take advantage of the lower divertor diagnostics and connect to large database of LSN favorable grad-B drift direction discharges. Reversing the toroidal field will have several consequences that should provide a valuable test for ELM suppression and 3D transport theory: The equilibrium will be right-handed, thus the plasma resonance will be on the positive side of the poloidal mode spectrum. The even parity poloidal mode spectrum is symmetric, thus any difference between right and left-handed resonances will be due to error fields. However, the odd parity poloidal mode spectrum is not symmetric, so reversing the toroidal field will have a large impact on the resonant components. Comparing the plasma response to odd and even parity in right and left-handed equilibriums will provide more information on the nature of the plasma response to the vacuum poloidal mode spectrum and error fields. Neoclassical transport will change, altering the toroidal and poloidal flows near the separatrix. This most likely would change the plasma response by altering the penetration of magnetic perturbations. The larger L-H power threshold will allow a test of plasma response in high-powered L-modes where a weak Te and ne pedestal exist. This may lead to a plasma response more like H-mode (pump-out with minimal temperature response) than L-mode (edge collapse of density and temperature). Diagnostics such as the 3D magnetics and the soft x-ray camera would benefit from testing the detection and analysis of n=3 perturbations in LSN with reversed helicity and co-Ip torque.	ITER IO Urgent Research Task :	No
Experimental Approach/Plan:	The primary objective is to characterize the plasma response to an n=3 magnetic perturbation in L- and H-mode with the toroidal field reversed. This could include phase flips, RMP amplitude scan, even/odd parity and beta scan. The plasma shape would be chosen to match a low-collisionallity LSN ELM suppressed discharge in favorable grad-B direction, preferably with large heating power. If ELM suppression is achieved with reversed toroidal field, the experiment will focus on documenting the plasma response in this particular condition.
Background:	Previous experiments with RMP ELM suppression in the unfavorable grad-B drift direction used USN. As the I-coil current was increased, the discharge would back transition (H-L) before ELM suppression was observed. This experiment would be tried again using a LSN shape (more experience on density control in this configuration) and larger heating power (if available) to maintain H-mode.
Resource Requirements:	One run day to fully develop target discharge and document plasma response.
Diagnostic Requirements:	All available profile and divertor diagnostics.
Analysis Requirements:	XGC0, Kinetic EFIT, Varyped
Other Requirements:	--