Recognizing the physics behind the fusion experiment designed by the new MIT MIT News

Eight years ago, MIT entered into a research agreement with Commonwealth Fusion Systems, a startup company, to develop the next-generation fusion research experiment, known as PARK, the forerunner of the practical, emission-free power plant.

Now, after many months of intensive research and engineering work, researchers who have been accused of determining and refining the physics behind the ambitious talkmac design have published a series of papers summarizing their progress and outlining key research questions to enable spark.

Overall, the task is moving smoothly and on track, says Martin Greenwald, deputy director of MIT’s Plasma Science and Fusion Center and one of the project’s lead scientists. He says the papers in this series provide a high level of confidence in plasma physics and performance predictions for spark. No unexpected obstacles or surprises were shown, and the rest of the challenges seemed worth managing. According to Greenworld, this sets a solid foundation for the operation of the device once built.

Greenwald wrote a presentation of a set of seven research papers written by 47 researchers from 12 institutes and published in a special issue today Plasma Physics Journal. Together, the papers outline the theoretical and laboratory physics for the new fusion system, which the consortium expects to begin construction next year.

Spark is thought to be the first experimental device to achieve “burning plasma” – a self-sustaining fusion reaction in which different isotopes of the element hydrogen fuse combine to form helium, without the need for any energy input. . The study of the behavior of this burning plasma – something never seen before on Earth in a controlled fashion – is seen as crucial information for the development of the next step, a functional prototype of a practical, power-generating power plant.

Such fusion power plants can significantly reduce greenhouse gas emissions from the power-generation sector, a major source of these emissions globally. The MIT and CFS project is one of the largest privately funded research and development projects undertaken in the field of fusion.

“The MIT group is taking a very attractive approach to fusion.” Says Chris Hague, a professor of engineering physics at the University of Madison at Wisconsin, who was not involved in the work. “They realized that the emergence of high temperature superconducting technology enabled a high magnetic field approach to obtain net energy from a magnetic limit system. This task is a potential game-changer for the international fusion program.”

The spark design, despite being twice the size of MIT’s current retired Alcater C-mode experiment and similar to many other research fusion machines currently in operation, will be more powerful, comparable to the expected fusion performance in a larger ITER. Tokmak is being built in France by an international consortium. Power in small sizes is made possible by the advancement of high-strength superconducting magnets that allow hot plasma to be confined to a stronger magnetic field.

The Spark project was launched in early 2018, and work on its first phase, the development of superconducting magnets that will allow the construction of small fusion systems, is progressing rapidly. The new set of papers presents for the first time that the underlying physics basis for the spark machine has been described in detail in peer-reviewed publications. The seven papers explore specific areas of physics that had to be further refined, and that still require ongoing research to finalize the final elements of machine design and plant parenting processes and tests that will be involved as work moves toward the power plant. .

These papers also describe the use of calculations and simulation tools for the design of the spark, which has been tested against many experiments around the world. The authors used cutting-edge simulations, which run on powerful supercomputers, developed to aid the design of ITER. Large multi-institutional teams of researchers presented in a new set of papers aimed at bringing consensus tools in SPARC machine design to increase confidence in achieving its goal.

The analysis done so far shows that the planned fusion of Spark TalkMac should be able to meet design specifications with a comfortable margin to save energy output. It is designed to achieve the Q factor – a key parameter indicating the efficiency of fusion plasma – at least 2, which means that twice the amount of fusion produced to produce a reaction produces fusion. It will be the first time that any type of fusion plasma produces more energy than it consumes.

Calculations at this stage show that according to the new papers, the spark can actually achieve a Q ratio of 10 or more. While Greenwald warns that the team is careful not to over-appreciate, and that more work remains to be done, the results so far indicate that the project will at least achieve its goals, and in particular fulfill its main objective of producing burning plasma. Will, in which self-heating dominates the energy balance.

They say the limitations imposed by the Covid-19 epidemic have slowed progress a bit, but not much, and researchers have returned to labs under the new operating guidelines.

Overall, “We still aim to start construction around June ’21,” says Greenwood. “The physics effort is well integrated with the engineering design. What we’re trying to do is project the project on a physics basis.” So that we are confident about how it will operate, and then it provides guidance and answers to questions for engineering design. ”

The design of the machine covers many of the finer details on machine design, covering the best ways to obtain radiation and fuel, power, dealing with sudden thermal or power transistors, and how and where to measure key parameters. In order to monitor machine operation.

So far, only minor changes have been made to the overall design. The diameter of the talkmac has been increased by about 12 per cent, but the other has changed little, Greenwald says. “There’s always the question of getting a little less than this, and there are a lot of things that carry weight, engineering questions, mechanical stress, thermal stress, and even physics – how do you influence that? Machine? “

The publication of this special issue of the journal, he says, “presents a summary, which is like a snapshot of the standards of physics basis today.” Although team members have discussed many aspects of it in physics meetings, “this is our first opportunity to tell a story, review it, get an approval ticket and put it in the community.”

Greenwald says there is still much to learn about the physics of burning plasmas, and once the machine is turned on, key information can be obtained that will help pave the way for commercial, power-generating fusion devices whose fuels – hydrogen isotopes deuterium and tritium Can be made available in unlimited supply.

He says the details of Burning Plasma are “really novel and important.” “The big mountain we have to cross is to understand this self-heating state of plasma.”

“The analysis presented in these papers will provide an opportunity for the world-wide fusion community to better understand the physics of the spark device and measure itself to address the remaining challenges,” says Mechanical and Professor George Tinon. Aerospace engineering at the University of California at San Diego, who was not involved in the work. “His publication is an important goal on the road to the study of burning plasmas and on the road to the first demonstration of clean energy radiation production from controlled fusion, and we appreciate the authors for seeing it all.”

Overall, Greenwald says the work done in the analysis presented in this package of papers “helps validate our confidence that we will achieve the mission.” We don’t get to say anything, ‘Oh, this is predicting that we won’t get where we want to go. In short, he says, “One conclusion is that things are still looking on-track. We believe it will work.”