Congratulations to George Su from the Columbia University Fusion Research Center on winning a best PhD student presenter prize at the 13th Runaway Electron Modelling (REM) meeting, held June 15–18 at the KTH Royal Institute of Technology in Stockholm, Sweden. He shares the prize with Lorenzo Votta (KTH).
Su was recognized for his work on the benign termination of relativistic electron beams, a leading scheme for protecting tokamaks from the localized damage that runaway electrons can inflict during abrupt losses of the plasma current. In benign termination, hydrogenic injection drives magnetohydrodynamic (MHD) instabilities that spread the beam's heat load over a large area rather than allowing it to deposit on a single point. A long-standing puzzle has been the exact role of hydrogenic injection in the termination.
Su's work offers a first-principles answer. Combining kinetic modelling that includes neutrals with nonlinear MHD simulations, he showed that the plasma's resistivity governs access to benign termination: higher resistivity produces a more chaotic edge magnetic field and a larger wetted area over which the runaway beam deposits its energy. The result provides an experimentally consistent picture of the involved physics and presents an essential step toward extrapolating the benign scenario to next-step, reactor-scale devices such as ITER or SPARC.
The presenter prizes are sponsored by the Journal of Plasma Physics and were decided by an anonymous poll of the meeting participants. The Columbia Fusion Research Center congratulates George on this well-earned recognition and looks forward to his continued contributions to runaway electron research.
