Seven studies published last week reveal researchers are closer than ever to developing a fusion reactor that can lead to an electricity-providing, emissions-free power plant by 2030. The timeline is incredibly ambitious but the MIT-lead research team has not hit even one impediment thus far and consider the remaining challenges “manageable.”
“[The papers] help to validate our confidence that we will achieve the mission. We haven’t run into anything where we say, ‘oh, this is predicting that we won’t get to where we want,” said Martin Greenwald, deputy director of MIT’s Plasma Science and Fusion Center and one of the project’s lead scientists. “One of the conclusions is that things are still looking on-track. We believe it’s going to work.”
Nearly three years ago, MIT entered into a research agreement with startup company Commonwealth Fusion Systems to develop a next-generation fusion research experiment, called SPARC. Last week, in a series of seven papers authored by 47 researchers from 12 institutions published in a special issue of the Journal of Plasma Physics, the scientists express a high level of confidence in the plasma physics and the performance predictions for SPARC.
Together, the papers outline both the theoretical and empirical physics basis for the new fusion system, which the consortium expects to start building in June 2021. They explore the specific areas of the physics that had to be further refined, areas that require ongoing research in machine design and the operating procedures and tests that will be involved as work progresses toward the power plant. The papers also describe the use of calculations and simulation tools for the design of SPARC, which have been tested against many experiments around the world.
If SPARC succeeds, it will be the first device in the world to achieve a burning plasma, a self-sustaining fusion reaction that fuses together isotopes of hydrogen to form helium to generate energy—essentially mimicking the way the sun produces energy. Unlike conventional nuclear fission power plants, a fusion plant does not burn fossil fuels or produce greenhouse gas emissions, and does not rely on uranium, an element already in short supply. Thus, understanding the behavior of burning plasma is absolutely critical to moving toward an emissions-free power plant capable of generating electricity.
The SPARC design would be far more powerful than predecessors and the much larger ITER currently being built in France by an international consortium. SPARC is designed to achieve a Q factor—a key parameter denoting the efficiency of a fusion plasma—of at least 2, essentially meaning that twice as much fusion energy is produced as the amount of energy pumped in to generate the reaction. That would be the first time a fusion plasma of any kind has produced more energy than it consumed.
But there’s more—according to the new papers, current calculations show SPARC could actually achieve a Q ratio of 10 or more. The high-power, small-size design is made possible by recent advances in superconducting magnets that allow for a much stronger magnetic field to confine the hot plasma.
The scientists do caution that while the project is trending positively, there is still much work to be done. According to MIT representatives, many of the machine design details are still being worked out, in addition to solving the best ways of getting energy and fuel into the device, getting the power out, dealing with any sudden thermal or power transients, and how and where to measure key parameters to monitor the device’s operation.
Even after the machine is up and running, there will be much to do and learn. The device can unlock previously unattainable information regarding fusion plasma, element-derived fuel and electricity-producing green energy.
Greenwald said the plasma, in particular, can reveal critical insights,
“[Details of the burning plasma] are really novel and important,” he said. “The big mountain we have to get over is to understand this self-heated state of a plasma.”
True to MIT’s commitment to open access research, the new set of papers represents the first time that the underlying physics basis for the SPARC machine has been outlined in detail in peer-reviewed publications and put forth into the scientific literature community. The papers, which can all be viewed here, provide an in-depth snapshot of where scientists are today and where they plan to be in the future. If all goes well, we’ll be reading about their success in less than 10 years.
Photo: This image shows a cutaway rendering of SPARC, a compact, high-field, DT burning tokamak, currently under design by a team from MIT and Commonwealth Fusion Systems. Its mission is to create and confine a plasma that produces net fusion energy. Credits: CFS/MIT-PSFC — CAD Rendering by T. Henderson