Resonant magnetic perturbations explained

Resonant magnetic perturbations (RMPs) are a special type of magnetic field perturbations used to control burning plasma instabilities called edge-localized modes (ELMs) in magnetic fusion devices such as tokamaks. The efficiency of RMPs for controlling ELMs was first demonstrated on the tokamak DIII-D in 2003.^[1]

Normally the rippled magnetic field will only suppress ELMs for very narrow ranges of the plasma current.^[2]

See also

• Plasma instability
• COMPASS tokamak
• NSTX-U, also uses RMPs to control ELMs

Further reading

• Effect of resonant magnetic perturbations on ELMs in connected double null plasmas in MAST
• RMP ELM suppression in DIII-D plasmas with ITER similar shapes and collisionalities 2008, RMP for ITER-like plasma triangularity is harder
• Connection between plasma response and RMP ELM suppression in DIII-D Wingen 2015 free access
• Wide Operational Windows of Edge-Localized Mode Suppression by Resonant Magnetic Perturbations in the DIII-D Tokamak 2020 "The model predicts that wide q95 windows of ELM suppression can be achieved at substantially higher pedestal pressure in DIII-D by shifting to higher toroidal mode number (n=4) RMPs."

Notes and References

1. T.E. Evans . etal . 2004 . Suppression of Large Edge-Localized Modes in High-Confinement DIII-D Plasmas with a Stochastic Magnetic Boundary . . 92 . 23 . 235003 . 10.1103/PhysRevLett.92.235003. 2004PhRvL..92w5003E . 15245164.
2. https://scitechdaily.com/fusion-power-breakthrough-new-method-for-eliminating-damaging-heat-bursts-in-toroidal-tokamaks/ Fusion Power Breakthrough: New Method for Eliminating Damaging Heat Bursts in Toroidal Tokamaks