[PAST EVENT] Richard Murijono Tung Ming Reksoatmodjo: Physics Dissertation Defense 

November 16, 2022
10am - 1pm
Small Hall, 122 or Zoom
300 Ukrop Way
Williamsburg, VA 23185Map this location

Richard Murijono Tung Ming Reksoatmodjo, Final Oral Examination for the Ph.D. Degree, Title: "Edge Fueling and Neutral Density Studies of the Alcator C-Mod Tokamak Using the SOLPS-ITER Code"
Zoom info available upon request. Please email Ellie at evwilk@wm.edu.

Abstract: Understanding edge neutral dynamics in high-field tokamaks has strong consequences for both fueling and plasma profile predictions. We validate the ability of SOLPS-ITER, a 2D fluid plasma/kinetic Monte Carlo neutral code, to accurately model upstream neutral density profiles of L-mode, I-mode, and H-mode discharges in the Alcator C-Mod tokamak. Via iterative tuning of perpendicular transport coefficient profiles alone, we achieve simulated Lyman-alpha emission and neutral density profiles within one error bar of empirical measurements for all discharges, providing confidence in the baseline SOLPS model to accurately simulate neutrals in the upstream plasma edge.

SOLPS is then used to assess the relative role of edge fueling versus transport in high density Alcator C-Mod discharges approaching fusion-relevant opaqueness conditions. We model a set of high density H-mode discharges with gas puffs of varying magnitude applied to probe the response of the density pedestal to increased edge fueling. Analysis of the simulated radial neutral e-folding length reveals that in high opacity conditions, neutrals tend to get trapped in the PFR, suggesting that upstream fueling dominates x-point fueling, an important consideration for future fusion devices operating in high density regimes.

Bio: Richard Reksoatmodjo was born on March 21, 1995 in Los Gatos, California. Growing up in Santa Cruz, CA, he became curious about many things related to science and math, but particularly that related to electromagnetism and clean energy. In 2013, he enrolled at Embry-Riddle Aeronautical University in Prescott, Arizona, where he studied Space Physics and minored in Mathematics. He graduated Summa Cum Laude in 2017 as the Outstanding Student in Physics. Dissatisfied with only four years of college-level physics, he entered William & Mary in the fall of 2017. There he studied plasma physics and fusion sciences under Dr. Saskia Mordijck. After graduation, he aspires to continue pursuing a research career in nuclear fusion as a national lab postdoctoral researcher, and hopefully one day as a university physics professor.