Model Validation for Next Generation Fusion Facilities

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The U.S. Department of Energy’s (DOE) Princeton Plasma Physics Laboratory (PPPL) Flagship Fusion Facility Could Serve as a Model for an Economically Attractive Next-Generation Fusion Pilot Plant, According to Recent Simulations and Analysis . The pilot plant could become America’s next step in harvesting the fusion energy on Earth that powers the sun and stars as a safe and clean energy source to generate electricity.

The US fusion community recently called for an immediate effort to design and build a cost-effective pilot plant to generate electricity in the 2040s. The unique capabilities of PPPL’s ​​flagship, the National Spherical Torus Experiment-Upgrade (NSTX- U) which is currently being repaired, made his design a candidate for this role. “It’s about trying to project whether this path is favorable for a profitable pilot plant and beyond,” said senior physicist Walter Guttenfelder, lead author of a paper in the journal nuclear fusion which details the latest findings.

Fusion produces great energy by combining light elements such as hydrogen in the form of plasma, the hot and charged state of matter composed of free electrons and atomic nuclei or ions. Plasma makes up 99% of the visible universe and powers fusion reactions that produce heat and light that create and sustain life on Earth.

The spherically shaped NSTX-U produces high-pressure plasmas needed for fusion reactions in a relatively compact and economical configuration. The operating capabilities of the facility are greatly improved compared to its pre-upgraded predecessor. “The main motivation for NSTX-U is to push to even higher powers, higher magnetic fields supporting high temperature plasmas to see if the favorable trends previously observed continue,” Guttenfelder said.

Recent theory, analysis, and modeling from the NSTX-U research team predict that many of these trends should be demonstrated in new NSTX-U experiments. The expected operating conditions for the NSTX-U are as follows:

Plasma start. The modeling was developed to efficiently optimize plasma initiation and ramp-up, and it was applied to help a spherical tokamak facility in the UK produce its first plasma.

Understanding the plasma edge. New models simulate the dynamics between the plasma edge and the tokamak wall that can determine whether the plasma core will reach the 150 million degree temperatures needed to produce fusion reactions.

Application of artificial intelligence. AI machine learning has developed a fast path to optimize and control plasma conditions that closely match intended test targets.

New technics. Simulations suggest many new techniques to protect interior NSTX-U components from exhaust heat blasts from fusion reactions. Among these concepts is the use of vaporized lithium to reduce the impact of heat flow.

Stable performance. Studies have shown that an NSTX-U performance window can remain stable in the face of instabilities that can degrade operations.

What to avoid. A better understanding of the conditions to avoid comes from an excellent agreement between the predicted range of unstable plasmas and a large experimental database.

Considerable progress has therefore been made in understanding and projecting how NSTX-U can advance the development of fusion energy, nuclear fusion the paper says. “The next step,” Guttenfelder said, “is to see if new experiments validate what we predict, and to refine the predictions if they don’t. These steps together will allow for more reliable projections for future devices.”

Support for this research comes from the DOE Office of Science with many simulations produced using resources from the National Energy Research Scientific Computing Center, a user facility of the DOE Office of Science. The paper’s co-authors include researchers from PPPL and 23 collaborating institutions around the world.

Source of the story:

Material provided by DOE/Princeton Plasma Physics Laboratory. Original written by John Greenwald. Note: Content may be edited for style and length.

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