Resonant magnetic perturbations (RMPs) are a special type of
magnetic field
A magnetic field is a vector field that describes the magnetic influence on moving electric charges, electric currents, and magnetic materials. A moving charge in a magnetic field experiences a force perpendicular to its own velocity and t ...
perturbations used to control
burning plasma
Plasma, one of the four fundamental states of matter, consists of a gas of ions and free electrons. A burning plasma is one in which most of the plasma heating comes from fusion reactions involving thermal plasma ions.
The Sun
In the Sun and o ...
instabilities called
edge-localized mode An edge-localized mode (ELM) is a disruptive instability occurring in the edge region of a tokamak plasma due to the quasi-periodic relaxation of a transport barrier previously formed during a transition from low to high-confinement mode. This phen ...
s (ELMs) in magnetic fusion devices such as
tokamak
A tokamak (; russian: токамáк; otk, 𐱃𐰸𐰢𐰴, Toḳamaḳ) is a device which uses a powerful magnetic field to confine plasma in the shape of a torus. The tokamak is one of several types of magnetic confinement devices being ...
s. The efficiency of RMPs for controlling ELMs was first demonstrated on the tokamak
DIII-D
DIII-D is a tokamak that has been operated since the late 1980s by General Atomics (GA) in San Diego, USA, for the U.S. Department of Energy. The DIII-D National Fusion Facility is part of the ongoing effort to achieve magnetically confined fusion ...
in 2003.
[
]
Normally the rippled magnetic field will only suppress ELMs for very narrow ranges of the plasma current.
''Fusion Power Breakthrough: New Method for Eliminating Damaging Heat Bursts in Toroidal Tokamaks''
/ref>
See also
*Plasma instability
The stability of a plasma is an important consideration in the study of plasma physics. When a system containing a plasma is at equilibrium, it is possible for certain parts of the plasma to be disturbed by small perturbative forces acting on it ...
*COMPASS tokamak
COMPASS, short for Compact Assembly, is a compact tokamak fusion energy device originally completed at the Culham Science Centre in 1989, upgraded in 1992, and operated until 2002. It was designed as a flexible research facility dedicated mostly ...
* NSTX-U, also uses RMPs to control ELMs
References
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."
Plasma physics
Tokamaks
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