Korea Superconducting Tokamak Advanced Research, or KSTAR, scientists have succeeded in sustaining a plasma gas at 100 million kelvin for up to 20 seconds without experiencing significant instabilities. This result is thought to be a significant step forward in the development of a sustainable nuclear fusion reaction.

The KSTAR team’s research paper has been published in Nature.

This result is a major development though a sustainable reactor that produces more energy than it consumes will be a product in the future.

A recent view of the KSTAR tokamak reactor. Image Credit: Korea Superconducting Tokamak Advanced Research.

A primary problem is maintaining the stability and temperature of plasma – the fourth state of matter made up of unbound ions or charged atoms. The KSTAR operates using a hydrogen plasma confined by a magnetic field.

So far scientists have been unable to achieve a sustainable fusion performance, which requires a high temperature above 100 million kelvin and sufficient control of instabilities to ensure steady-state operation in the order of tens of seconds.

The KSTAR scientists now report they have overcome the threshold saying in the Nature paper, “Here we report experiments at the Korea Superconducting Tokamak Advanced Research device producing a plasma fusion regime that satisfies most of the above requirements.”

The authors added, “A low plasma density combined with a moderate input power for operation is key to establishing this regime by preserving a high fraction of fast ions. This regime is rarely subject to disruption and can be sustained reliably even without a sophisticated control, and thus represents a promising path towards commercial fusion reactors.”

The paper’s abstract noted, “A low plasma density combined with a moderate input power for operation is key to establishing this regime by preserving a high fraction of fast ions. This regime is rarely subject to disruption and can be sustained reliably even without a sophisticated control, and thus represents a promising path towards commercial fusion reactors.”

The paper explains a device producing a plasma fusion regime that satisfies most of the above requirements: thanks to abundant fast ions stabilizing the core plasma turbulence, we generate plasmas at a temperature of 100 million kelvin lasting up to 20 seconds without plasma edge instabilities or impurity accumulation.

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Here’s a fact, credible confidence that tokamak fusion will work and confidence that it will work 24 hours a day, seven days a week, 365 days a year and satisfy the economic environment in which it’s got to live does not exist.

Then consider that your energy product is heat at 100,000,000° K. Its likely that dry steam at 700° F will be the goal for driving generators. The question that comes up is, after corralling the heat and making steam, how much electrical energy do you get compared to what went in to drive the fusion?

Getting from the physics to the practical engineering seems to lack materials and processes.

There are other ideas with other types of output. Robert W. Bussard’s polywell comes to mind.


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