Novel concept suppressing plasma heat pulses in a tokamak by fast divertor sweeping

Abstract

One of the remaining challenges in magnetic thermonuclear fusion is survival of the heat shield protecting the tokamak reactor vessel against excessive plasma heat fluxes. Unmitigated high confinement edge localized mode (ELM) is a regular heat pulse damaging the heat shield. We suggest a novel concept of magnetic sweeping of the plasma contact strike point fast and far enough in order to spread this heat pulse. We demonstrate feasibility of a dedicated copper coil in a resonant circuit, including the induced currents and power electronics. We predict the DEMO ELM properties, simulate heat conduction, 3D particles motion and magnetic fields of the plasma and coil in COMSOL Multiphysics and Matlab. The dominant system parameter is voltage, feasible 18 kV yields 1 kHz sweeping frequency, suppressing the ELM-induced surface temperature rise by a factor of 3. Multiplied by other known mitigation concepts, ELMs might be mitigated enough to ensure safe operation of DEMO.

Model-based impurity emission front control using deuterium fueling and nitrogen seeding in TCV

“…If impurity injection is used to mitigate radiative fluctuations in the plasma exhaust this accumulation would become a limiting factor in control performance, strategies where impurity injection is kept to a minimum would be required. This is in line with the strategic operation of control, that must simultaneously encompass a limit of reattachment (which can still be temporarily endured by using, for example, strike-point sweeping [35][36][37]), and a hard limit resulting from radiative instability induced disruptions.…”