Reduced edge instability and improved confinement in the MST reversed-field pinch

Area of Science:

• Plasma Physics
• Fusion Energy Research
• Magnetohydrodynamics

Background:

• Improved plasma confinement is crucial for fusion energy.
• Edge-resonant instabilities have limited confinement in MST reversed-field pinch (RFP) plasmas.
• Previous efforts focused on poloidal electric field control, but were insufficient.

Purpose of the Study:

• To suppress edge-resonant instabilities in MST RFP plasmas.
• To enhance plasma confinement beyond previously observed scaling.
• To achieve record energy confinement times and high beta values.

Main Methods:

• Refined control of the poloidal electric field.
• Introduction of toroidal electric field control.
• Suppression of edge-resonant instability bursts.

Main Results:

• Suppression of edge-resonant instability bursts was achieved.
• A total beta of 15% was reached.
• An estimated energy confinement time of 10 ms was recorded, a tenfold increase.

Conclusions:

• Combined poloidal and toroidal electric field control effectively suppresses edge-resonant instabilities.
• This method leads to substantially improved energy confinement in RFP plasmas, exceeding standard scaling.
• The achieved results represent a significant advancement for RFP confinement and fusion energy research.