Edge Localized Modes (ELMs)
Periodic magnetohydrodynamic bursts occurring at the boundary edge pedestal of H-mode tokamak plasmas, expelling heat and particles toward reactor walls.
Governing formula
Magnetohydrodynamic Peeling-Ballooning Boundary Instability
SI unit
MJ (Energy Loss Pulse per ELM)
In depth
Driven when edge pressure gradients and current densities exceed peeling-ballooning MHD stability thresholds. Periodic ELM eruptions dump high heat loads onto divertor armor plates.
Examples in the real world
Using resonant magnetic perturbation (RMP) coils in tokamaks to mitigate or eliminate giant ELM bursts.