JPP lays out SPARC fusion physics basis

Cutaway of the SPARC engineering design. Image: CFS/MIT-PSFC, CAD rendering by T. Henderson

Seven open-access, peer-reviewed papers on the design of SPARC, Commonwealth Fusion Systems’ (CFS) fusion tokamak, written in collaboration with the Massachusetts Institute of Technology’s Plasma Science and Fusion Center, were published on September 29 in a special edition of the Journal of Plasma Physics.

The papers describe a compact fusion device that will achieve net energy where the plasma generates more fusion power than used to start and sustain the process, which is the requirement for a fusion power plant, according to CFS.

The timeline for this planned device sets it apart from other magnetic confinement fusion tokamaks: Construction is to begin in 2021, with the device coming on line in 2025.

CFS expects the device to achieve a burning plasma—a self-sustaining fusion reaction—and become the world’s first net energy (Q>1) fusion system. The newly released papers reflect more than two years of work by CFS and the Plasma Science and Fusion Center to refine their design. According to CFS, the papers apply the same physics rules and simulations used to design ITER, now under construction in France, and predict, based on results from existing experiments, that SPARC will achieve its goal of Q>2. In fact, the papers describe how, under certain parameters, SPARC could achieve a Q ratio of 10 or more.

A look inside the TFTR plasma vessel. Photo: DOE

The Tokamak Fusion Test Reactor (TFTR) at Princeton University and the Fuel Cycle Facility (FCF) (now known as the Fuel Conditioning Facility) at Idaho National Laboratory have been designated as ANS Nuclear Historic Landmarks. The official awarding of the honors will occur during the 2020 ANS Virtual Winter Meeting, which begins November 16.

The TFTR received the award for demonstrating significant fusion energy production and tritium technologies for future nuclear fusion power plants and for the first detailed exploration of magnetically confined deuterium-tritium (D-T) fusion plasmas.

INL’s FCF and its Experimental Breeder Reactor II (EBR-II) were honored for demonstrating on-site recycling of used nuclear fuel back into a nuclear reactor.

The NSTX-U “umbrella.” Photo: Elle Starkman/ PPPL Office of Communications

The Department of Energy on September 8 announced funding for research at the National Spherical Tokamak Experiment Upgrade (NSTX-U), an Office of Science user facility at the DOE’s Princeton Plasma Physics Laboratory in Princeton, N.J.

Total planned funding is $17 million for the NSTX-U work over five years in duration. As much as $6 million in fiscal year 2020 dollars and out-year funding could be available this year, contingent on congressional appropriations and satisfactory progress.

The initiative will support experiments, data analysis, and computer modeling and simulation of plasma behavior. A major focus will be on the start of laying the scientific groundwork for a next-generation facility through better understanding of the behavior of plasmas in spherical tokamaks, the DOE said.

The Department of Energy announced on September 2 that it has issued $29 million in funding for 14 projects as part of its Galvanizing Advances in Market-aligned fusion for an Overabundance of Watts (GAMOW) program, which is jointly sponsored by the department’s Advanced Research Projects Agency–Energy (ARPA-E) and the Office of Science–Fusion Energy Sciences (SC-FES).

According to the DOE, GAMOW teams will work to close multiple fusion-specific technological gaps that will be needed to connect a net-energy-gain “fusion core,” once it is ready, to a deployable, commercially attractive fusion system.

The Department of Energy on August 19 announced several awards to research teams applying artificial intelligence and machine learning to fusion energy. The planned total funding of $21 million is targeted at projects with time frames of up to three years; $8 million in fiscal year 2020 funding has already been committed to the work. Delivery of the balance-of-project funding will depend on future congressional appropriations.

“These awards will enable fusion researchers to take advantage of recent rapid advances in artificial intelligence and machine learning,” said Chris Fall, director of the DOE’s Office of Science. “AI and ML will help us to accelerate progress in fusion and keep American scientists at the forefront of fusion research.”

PPPL physicists Raffi Nazikian (left) and Qiming Hu, with a figure from their research. Photo: PPPL/Elle Starkman

Stars contain their plasma with the force of gravity, but here on earth, plasma in fusion tokamaks must be magnetically confined. That confinement is tenuous, because tokamaks are subject to edge localized modes (ELM)—intense bursts of heat and particles that must be controlled to prevent instabilities and damage to the fusion reactor.

Researchers at the Department of Energy’s Princeton Plasma Physics Laboratory (PPPL) and at General Atomics (GA) recently published a paper in Physical Review Letters explaining this tokamak restriction and a potential path to overcome it. They have developed a new model for ELM suppression in the DIII-D National Fusion Facility, which is operated by GA for the DOE. PPPL physicists Qiming Hu and Raffi Nazikian are the lead authors of the paper, which was announced on August 10 by PPPL.

Separation of Kr-85 from spent nuclear fuel by a highly selective metal organic framework. Image: Mike Gipple/National Energy Technology Laboratory

According to a story published by the Massachusetts Institute of Technology on July 24, the capture of gaseous fission products such as krypton-85 during the reprocessing of spent nuclear fuel could be aided by the adsorption of gasses into an advanced type of soft crystalline material, metal organic frameworks(MOF), which feature high porosity and large internal surface areas that can trap an array of organic and inorganic compounds.

Those attending the livestreamed July 28 celebration in person (shown here from above) followed recommended social distancing measures.

First-of-a-kind components have been arriving in recent months at the ITER construction site in Cadarache, France, from some of the 35 ITER member countries around the world. The arrival on July 21 of the first sector of the ITER vacuum vessel from South Korea marks the beginning of a four-and-a-half year machine assembly process for the world’s largest tokamak, a magnetic fusion device designed to prove the feasibility of fusion as an energy source.

A three-part free webinar workshop, Separating Nuclear Reactors from the Power Block with Heat Storage: A New Power Plant Design Paradigm, will run for three upcoming Wednesdays, starting this week on July 29. The workshop is being hosted jointly by the Massachusetts Institute of Technology (MIT), Idaho National Laboratory (INL), and the Electric Power Research Institute (EPRI).