Demonstrating the Suppression of Edge-Localized Modes via Resonant Magnetic Perturbations in Hydrogen Plasmas

2023 Research Campaign, Prepare for ITER Task Force

Purpose of Experiment

Transient heat loads in the divertor caused by edge-localized modes (ELMs) are predicted to exceed material thresholds in the next step fusion device ITER. Therefore, mitigation or suppression of ELMs will be essential and can be achieved by applying resonant magnetic perturbations (RMPs). The ITER pre-fusion power operation phase utilizes hydrogen and/or helium plasmas at reduced plasma current and toroidal field. This phase should be used to demonstrate the feasibility of techniques and scenarios developed at today’s devices that are critical for safe and successful operation in the following high plasma current high toroidal field deuterium/tritium campaigns. While complete ELM suppression has been demonstrated in deuterium plasma in many different tokamaks worldwide, it has yet me be demonstrated in hydrogen plasmas. This experiment aims at suppressing ELMs via RMPs in hydrogen plasmas by attempting to match the H-mode pedestal to those in deuterium.

Experimental Approach

The plan of this experiment is to create a hydrogen plasma that matches all access criteria to RMP- ELM suppression that have been identified in deuterium plasmas. Those are in particular operating in the correct edge safety factor windows, pedestal top density below the critical threshold, toroidal pedestal top rotation above the critical threshold and a plasma shape that is similar to ITER’s. Some access criteria for ELM suppression are not identified clearly yet which may make it necessary to also match other parameters to deuterium plasma, such as the electron and ion pedestal top temperatures. The different knobs that allow to control all these criteria are the plasma current, toroidal magnetic field, shaping coil currents, gas fueling as well as heating with neutral beam injection and electron cyclotron resonance systems.

See more details, including project leads, at U.S. Department of Energy, Office of Scientific and Technical Information (OSTI).