New research shows that plasma fusion heat spreads more evenly in tokamak reactors, a milestone in the field of fusion energy. This suggests new ways to improve reactor efficiency and overall service life while reducing the chance of damage.
The new findings from researchers at the US Department of Energy’s (DOE) Princeton Plasma Physics Laboratory (PPPL), in collaboration with Oak Ridge National Laboratory and ITER, currently the largest fusion experiment in the world, show that when reactors on commercial produce large quantities of hydrogen on a large scale Due to the very intense heat emission during plasma fusion, this may not be as potentially harmful to the interior of the reactor as was assumed.
The new research could provide new opportunities to extend the operational life of fusion reactors and upend previous perceptions about the movement of heat and particles between two critical regions at the edge of plasma during the fusion process. The new research was led by PPPL Managing Principal Research Physicist Choongseok Chang.
Tokamaks are large toroidal (that is, doughnut-shaped) devices that scientists use to produce controlled fusion reactions from hot plasmas. During operation, temperatures within a tokamak can often exceed 150 million degrees Celsius to achieve fusion, mimicking processes that naturally occur on the sun and exceeding solar temperatures by about ten times.
Tokamaks require magnetic fields to confine the plasmas within the core of the device, although a few particles and excess heat will escape and collide with the inner walls.
However, based on Chang and his team’s findings, these escaping particles are spread over a larger area than previous findings had suggested, limiting the potential for serious damage.
In the past, it was believed that exhaust heat during fusion reactions would be more closely concentrated on so-called divertor plates. This portion of the inner wall of the tokamak is critical in helping to remove exhaust heat and particles from the hot plasmas within the tokamak. However, concentrations along the divertor plates can sometimes lead to damage, limiting the potential for commercial scale use.
In new simulations conducted by Chang and his team using a computer code known as plasma separates within the magnetic field is disrupted. tokamak from the unrestricted plasma, including the plasma arriving in the divertor area.
Over time, Chang’s research had shown that ions appeared to cross the boundary, concentrating the heat load on a highly focused region of the divertor plate, and that plasma turbulence caused negatively charged electrons to cross the boundary, causing the heat impact zone on the divertor became significantly larger. plates in ITER, the multinational fusion facility currently under construction in France.
However, Chang and the international team’s recent research found that the final confining surface, previously thought to be stable, is disrupted by plasma turbulence during fusion, resulting in what the researchers describe as a “homoclinic tangle.”
Homoclinic tangles were found to increase the width of the heat attack zone by as much as 30 percent more than previous estimates based solely on turbulence had shown. Chang and the team say that the broader heat distribution they discovered in their simulations makes it much less likely that the divertor surface will be damaged when accompanied by radiative cooling that results from the injection of impurities into the divertor plasma.
Although the final confining surface within a tokamak cannot be completely relied upon, the new research nonetheless demonstrates that this instability can actually improve fusion performance and reduce the chance of damage to the divertor surface during steady-state operation.
The risk of sudden release of plasma energy is also reduced. These findings address two of the major performance limiting issues that fusion energy researchers have faced regarding the future commercial use of tokamak reactors.
Micah Hanks is editor-in-chief and co-founder of The Debrief. He can be reached by email at micha@thedebrief.org. Follow his work michahanks.com and on X: @MichaHanks.