Researchers at the Princeton Plasma Physics Laboratory (PPPL) have developed a method to stabilize fusion plasmas by applying increased RF power to unstable 'bubbles' within the plasma. This approach enhances the efficiency of the stabilization process by leveraging the feedback between temperature perturbations and current drive sensitivity. The findings indicate that cooler regions in the plasma, which have higher electrical resistance, can absorb RF power, leading to temperature increases that correct instabilities. This novel understanding addresses the sudden collapse of heat in tokamak fusion facilities, which can lead to disruptions and damage.
PREREQUISITESPhysicists, fusion researchers, and engineers involved in plasma physics and tokamak design will benefit from this discussion, particularly those focused on improving plasma stability and efficiency in fusion energy production.
What I got out of this--please correct me if I am wrong--is that cooler regions in the plasma have a naturally higher electrical resistance. When they form the current driven through the plasma, to reach and maintain fusion temperatures, avoids them (taking the path of least resistance) and they cool more. But these cooler regions also happen to be more receptive to RF power, which they absorb, causing their temperature to rise and correcting the instability.https://phys.org/news/2019-01-scientists-stabilizes-fusion-plasmas.html said:The physical mechanism that PPPL has identified works like this:
- The temperature perturbations affect the strength of the current drive and the amount of RF power deposited in the islands.
- The perturbations and their impact on the deposition of power feedback against each other in a complex—or nonlinear—manner.
- When the feedback combines with the sensitivity of the current drive to temperature perturbations, the efficiency of the stabilization process increases.
- Furthermore, the improved stabilization is less to likely to be affected by misaligned current drives that fail to hit the center of the island.
It seems to be something like that. A 'better' (but still not real clear) definition can be found (especially in the last 2 paragraphs) at:jackwhirl said:What I got out of this--please correct me if I am wrong--is that cooler regions in the plasma have a naturally higher electrical resistance. When they form the current driven through the plasma, to reach and maintain fusion temperatures, avoids them (taking the path of least resistance) and they cool more. But these cooler regions also happen to be more receptive to RF power, which they absorb, causing their temperature to rise and correcting the instability.
https://phys.org/news/2022-09-scientists-fusion-energy-sun-stars.htmlPhysicists at the U.S. Department of Energy's (DOE) Princeton Plasma Physics Laboratory (PPPL) have proposed the source of the sudden and puzzling collapse of heat that precedes disruptions that can damage doughnut-shaped tokamak fusion facilities.
Researchers traced the collapse to the 3D disordering of the strong magnetic fields that bottle up the hot, charged plasma gas that fuels the reactions. "We proposed a novel way to understand the [disordered] field lines, which was usually ignored or poorly modeled in the previous studies," said Min-Gu Yoo, a post-doctoral researcher at PPPL and lead author of a Physics of Plasmas paper selected as an editor's pick together with a figure placed on the cover of the July issue. Yoo has since become a staff scientist at General Atomics in San Diego.
The strong magnetic fields substitute in fusion facilities for the immense gravity that holds fusion reactions in place in celestial bodies. But when disordered by plasma instability in laboratory experiments the field lines allow the superhot plasma heat to rapidly escape confinement. Such million-degree heat crushes plasma particles together to release fusion energy and can strike and damage fusion facility walls when released from confinement.