According to recent simulations and analysis, the flagship fusion facility of the United States Department of Energy’s (DOE) Princeton Plasma Physics Laboratory (PPPL) might serve as the model for an economically appealing next-generation fusion pilot plant. The pilot plant could be the next step in the United States toward collecting the fusion power that powers the sun and stars on Earth as a safe and clean source of power for producing energy.


The fusion community in the United States has recently pushed for an urgent effort to develop and build a cost-effective pilot plant capable of generating electricity in the 2040s. The PPPL flagship, the National Spherical Torus Experiment-Upgrade (NSTX-U), which is currently being repaired, has unique features that make its design suitable for that role. “It’s all about trying to project whether this route is favorable for a cost-effective pilot plant and beyond,” said Walter Guttenfelder, principal physicist and main author of a study detailing the new discoveries published in the journal Nuclear Fusion.

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

Physicist Walter Guttenfelder with figures from the paper he authored with PPPL researchers including members of the NSTX-U team and 23 collaborative institutions world-wide. Credit: Photo by Elle Starkman/PPPL Office of Communications; collage by Kiran Sudarsanan

The spherically shaped NSTX-U produces high-pressure plasmas required for fusion reactions in a relatively compact and cost-effective configuration. Operating capabilities of the facility are greatly enhanced over its pre-upgraded predecessor. “The primary motivation for NSTX-U is to push up to even higher powers, higher magnetic fields supporting high-temperature plasmas to see if previously observed favorable trends 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. Predicted operating conditions for the NSTX-U include the following:

• Starting up plasma. Modeling has been developed to efficiently optimize plasma initiation and ramp up, and it was applied to help a spherical tokamak facility in the United Kingdom produce its first plasma.
• Understanding the plasma edge. New models simulate the dynamics between the edge of the plasma and the tokamak wall that can determine whether the core of the plasma will reach the 150 million-degree temperatures needed to produce fusion reactions.
• Applying artificial intelligence. AI machine learning has developed a rapid path for optimizing and controlling plasma conditions that closely match predicted test targets.
• Novel techniques. Simulations suggest many novel techniques for shielding interior NSTX-U components from blasts of exhaust heat from fusion reactions. Among these concepts is the use of vaporized lithium to reduce the impact of heat flux.
• Stable performance. Studies found that a window for NSTX-U performance can remain stable in the face of instabilities that could degrade operations.
• What to avoid. Increased understanding of the conditions to avoid come from 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, the Nuclear Fusion paper says. “The next step,” said Guttenfelder, “is to see if new experiments validate what we’re predicting, and to refine the predictions if not. These steps together will enable more confident projections for future devices.”

Reference: “NSTX-U theory, modeling and analysis results” by W. Guttenfelder, D.J. Battaglia, E. Belova, N. Bertelli, M.D. Boyer, C.S. Chang, A. Diallo, V.N. Duarte, F. Ebrahimi, E.D. Emdee, N. Ferraro, E. Fredrickson, N.N. Gorelenkov, W. Heidbrink, Z. Ilhan, S.M. Kaye, E.-H. Kim, A. Kleiner, F. Laggner, M. Lampert, J.B. Lestz, C. Liu, D. Liu, T. Looby, N. Mandell, R. Maingi, J.R. Myra, S. Munaretto, M. Podestà, T. Rafiq, R. Raman, M. Reinke, Y. Ren, J. Ruiz Ruiz, F. Scotti, S. Shiraiwa, V. Soukhanovskii, P. Vail, Z.R. Wang, W. Wehner, A.E. White, R.B. White, B.J.Q. Woods, J. Yang, S.J. Zweben, S. Banerjee, R. Barchfeld, R.E. Bell, J.W. Berkery, A. Bhattacharjee, A. Bierwage, G.P. Canal, X. Chen, C. Clauser, N. Crocker, C. Domier, T. Evans, M. Francisquez, K. Gan, S. Gerhardt, R.J. Goldston, T. Gray, A. Hakim, G. Hammett, S. Jardin, R. Kaita, B. Koel, E. Kolemen, S.-H. Ku, S. Kubota, B.P. LeBlanc, F. Levinton, J.D. Lore, N. Luhmann, R. Lunsford, R. Maqueda, J.E. Menard, J.H. Nichols, M. Ono, J.-K. Park, F. Poli, T. Rhodes, J. Riquezes, D. Russell, S.A. Sabbagh, E. Schuster, D.R. Smith, D. Stotler, B. Stratton, K. Tritz, W. Wang and B. Wirth, 30 March 2022, Nuclear Fusion.
DOI: 10.1088/1741-4326/ac5448

Support for this research comes from the DOE Office of Science with many simulations produced using resources of the National Energy Research Scientific Computing Center, a DOE Office of Science User Facility. Coauthors of the paper include researchers from PPPL and 23 collaborative institutions world-wide.

PPPL, on Princeton University’s Forrestal Campus in Plainsboro, N.J., is devoted to creating new knowledge about the physics of plasmas — ultra-hot, charged gases — and to developing practical solutions for the creation of fusion energy.

3 in 5 parents say it’s hard to get their child to eat a well-balanced diet because of picky eating, not eating enough fruits and vegetables, and other reasons.

When it comes to eating the healthful things on their plate, children can be stubborn.

And now, a new national poll reaffirms that picky eating is indeed a universal parenting challenge.

According to the University of Michigan Health C.S. Mott Children’s National Poll on Children’s Health, more than half of parents think that it is difficult to get their child to eat a well-balanced diet, and half say their child routinely takes a supplement.

“A balanced diet helps children get the nutrients they need for healthy growth and development,” said Mott Poll co-director Sarah Clark, M.P.H. “An unhealthy diet, on the other hand, can negatively affect short and long-term health outcomes as well as school performance.

“Still, the reality for many parents is that getting children to eat healthy foods isn’t always easy. Our poll finds that many turn to dietary supplements as a solution but may not always consult with a health provider.”

Many parents report problems with their child’s diet, suggests a new national poll from University of Michigan. Credit: University of Michigan Health C.S. Mott Children’s National Poll on Children’s Health

About a third of parents say their child is a picky eater and a third don’t think they eat enough fruits and vegetables. Thirteen percent worried kids weren’t getting enough of certain vitamins and minerals while 9 % said their child needed more fiber in their diet, according to the nationally representative report based on responses from 1,251 parents with at least one child ages one to ten.

Another potential barrier: cost. Half of parents agreed that it was more expensive to provide their child with a healthy diet.

“We know that fresh, healthy foods can be more expensive than processed or packaged items that are often higher in sodium and added sugars,” Clark said.

“This can make it especially frustrating for parents when children waste or refuse to eat healthy foods.”

Most parents polled have given their child dietary supplements, with over three fourths using multivitamins. Close to half had also provided kids with probiotics, which are live bacteria and yeast taken to help digestion by enhancing the quantity of good microbes in the gut.

More than a fifth have used Omega 3 supplements, fatty acids that support cell growth and brain development.

About a third of parents say their child has tried but does not take supplements regularly.  Among parents who have given their child supplements, four in five say they chose products made specifically for children, but only about two in five say they discussed supplement use with their child’s health care provider.

Parents considering supplements will likely need to choose from various products and formulations that may claim specific health benefits.  

“Dietary supplements are often intended to enhance the amount of vitamins children consume through a regular diet,” Clark said. “But parents may not always know whether their child is getting proper nutrition.”

“The use of dietary supplements in children is an important health decision to discuss with doctors, but less than half of parents who have given their child a supplement talked to their child’s health provider.”

It’s unclear, she says, if this lack of consultation is the result of providers not asking about the child’s nutrition, parents not thinking supplement use warrants professional advice or another reason.

Parents in lower-income households were also less likely to talk about supplement use with their child’s health care provider, compared to higher-income parents, according to the report.

“Providers should be diligent about discussing nutrition with families so they understand what a healthy diet should include and are using supplements appropriately,” she said. “In situations where families can’t afford to provide a healthy diet, providers may direct parents to social service programs that can help.”

She noted that since supplements are classified by the U.S. Food and Drug Administration as food, they do not receive the same premarketing evaluation and review as medications.

“There is limited research on the safety and efficacy of supplements and potential side effects for kids. But some parents may not be aware that supplements do not undergo rigorous FDA testing and approval,” Clark said.

“To minimize the risks of supplement use, parents should share concerns about their child’s diet with a pediatrician who can help them identify the best strategies to improve the nutritional quality of their child’s diet and determine whether supplements are recommended.”