Ground-Breaking Efforts Overcome an Operational Limit of Tokamaks, Advancing Efforts to Achieve Fusion Energy

Fuel density in fusion tokamak devices has historically been constrained by limits in device design. Now, however, researchers at the DIII-D National Fusion Facility have for the first time gone beyond these density limits while simultaneously maintaining high confinement quality. These conditions have in the past been mutually exclusive. The result points to a possible solution for a common challenge for tokamak devices.

Yuan Ping: Then and Now / 2013 Early Career Award Winner

Yuan Ping developed a suite of measurement methods and produced data that scientists used to benchmark energy transport models. These models increase scientists’ control of fusion energy losses. The research team improved the efficiency of the energy conversion from the lasers to the final hot fuel.

Predicting Explosive Energy Bursts in Compact Fusion Power Plants

Edge localized modes (ELMs) associated with plasma instabilities in tokamak fusion reactors can damage reactor walls, a challenge in the design of future fusion power plants. Scientists have now discovered that internal resistance of the plasma can cause additional instabilities that drive ELMs in the National Spherical Torus Experiment. This will help researchers mitigate and control ELMs in spherical tokamaks.

For Plasma with a Hot Core and Cool Edges, Super-H Mode Shows Promise

Fusion reactors face a challenge called “core-edge integration,” which involves maintaining a plasma that is hot at the core but not too hot to damage reactor walls. New research finds that a previously identified operating regime called Super H-mode can leverage the use of impurities such as nitrogen to address this challenge. The research also indicates that Super-H mode can be scaled up to future fusion plants.

U.S. Researchers Simulate Compact Fusion Power Plant Concept

The Compact Advanced Tokamak (CAT) concept uses physics models to show that by carefully shaping the plasma and the distribution of current in the plasma, fusion plant operators can suppress turbulent eddies in the plasma. This would reduce heat loss and allow more efficient reactor operation. This advance could help achieve self-sustaining plasma and smaller, less expensive power plants.

Negative Triangularity—a Positive for Tokamak Fusion Reactors

In a conventional tokamak, the cross-section of the plasma is shaped like the letter D. Facing the straight part of the D on the inside side of the donut-shaped tokamak is called positive triangularity. New research suggests that reversing the plasma—negative triangularity–reduces how much the plasma interacts with the surfaces of the tokamak for reduced wear.

Scientists Solve Key Challenge for Controlling “Runaway” Electrons in Fusion Plasmas

Scientists at the DIII-D National Fusion Facility have for the first time studied the internal structure and stability of high-energy runaway electron (RE) beams in a tokamak. The finding could provide a way to control the damaging potential of RE beams and could contribute to future power production using tokamak fusion power plants.