Noninductively Driven Tokamak Plasmas at Near-Unity Toroidal Beta

Area of Science:

• Plasma Physics
• Fusion Energy Research
• Magnetohydrodynamics

Background:

• Achieving sustained, high-performance toroidal plasmas is crucial for fusion energy.
• Key goals include high plasma-to-magnetic pressure ratio (βt), low internal inductance, high elongation, and non-solenoidal current drive.
• Tokamak research aims to access this desirable parameter space for efficient fusion.

Purpose of the Study:

• To demonstrate stable access to a high-performance plasma regime in tokamaks.
• To investigate the use of local helicity injection for plasma sustainment and heating.
• To characterize the plasma properties, including βt, internal inductance, and magnetic well depth.

Main Methods:

• Utilizing plasmas with ultralow aspect ratio and high elongation.
• Employing local helicity injection for non-solenoidal current drive and sustainment.
• Performing equilibrium analyses to determine plasma parameters and stability.

Main Results:

• Stable access to the desirable high-performance parameter space was demonstrated.
• Local helicity injection successfully provided non-solenoidal sustainment and low internal inductance.
• Equilibrium analyses indicated achievable βt up to ~100% with a significant minimum |B| well.

Conclusions:

• Ultralow aspect ratio and high elongation plasmas enable access to high βt regimes.
• Local helicity injection is an effective method for achieving sustained, low-inductance toroidal plasmas.
• The demonstrated plasma properties are highly promising for future fusion energy applications.