SUBJECT: Ph.D. Proposal Presentation
BY: Theresa Wilks
TIME: Wednesday, March 25, 2015, 1:00 p.m.
PLACE: Love Building, 109
TITLE: The Effect of Ion Orbit Loss on the Calculation of the Radial Electric Field in the DIII-D Tokamak
COMMITTEE: Dr. Weston Stacey, Co-Chair (NRE)
Dr. Todd Evans, Co-Chair (General Atomics)
Dr. Bojan Petrovic (NRE)
Dr. Robert McGrath (GTRI)
Dr. Tris Utschig (NRE)


Changes in the radial electric field are correlated with changes in many important edge plasma parameters, including rotation, the L-H transition, and ELM suppression. A self-consistent model for the radial electric field may therefore provide a means of controlling other important parameters in the edge plasma. Implementing a methodology for calculating the radial electric field can be difficult due to the complex interrelationships among rotation, radial ion fluxes, momentum transport, and the radial electric field. The radial electric field enters the calculations for ion orbit loss. This ion orbit loss, in turn affects the radial ion flux both directly and indirectly through return currents, which has been shown theoretically to torque the edge plasma causing rotation. The edge rotation generates a motional radial electric field, both of which can influence the edge pedestal structure, and the ion orbit losses. The application of this methodology to interpret DIII-D H-mode and RMP shots is discussed.
Modeling efforts focus on improving calculations of ion orbit losses and x-loss into the divertor region, as well as formulation models for fast bean ion orbit losses and the fraction of lost particles that return to the confined plasma. Both diffusive and non-diffusive transport are taken into account in the modeling of the background plasma.