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Part 2 of 2 Parts (Please read Part 1 first)
        At MIT, a class was challenged with the task of finding a way to get rid of excess heat in reactors built to the new designs. Engineers from Mitsubishi Electric Research Laboratories and Commonwealth Fusion Systems worked with fourteen MIT students and Dennis Whyte, the director of MIT’s Plasma Science and Fusion Center who taught the class.
        Whyte compares the system used for expelling heat to the exhaust pipe of a car. He says that in the ARC design, the “pipe” that carries the heat away is longer and wider that the “pipes” that are used in earlier fusion reactor designs. Developing that better “pipe” for the ARC designs will require a lot of complex evaluation. Dozens of possible designs will have to be developed and tested to find the best one.

        In the MIT ARC reactors, the primary magnets are built in sections which can be disassembled. This means that the secondary coils can be installed inside the primary coils. Moving the secondary coils to inside the primary coils means that the secondaries can be smaller. This means that the diverters created by the secondaries can exert more precise control over the plasma and deal with the increase heat in the ARC reactors.
       Professor Whyte said, "It was really exciting, what we discovered. The result is divertors that are longer and larger, and that keep the plasma more precisely controlled. As a result, they can handle the expected intense heat loads. You want to make the 'exhaust pipe' as large as possible. It's really a revolution for a power plant design."

       The student project researched many different possible approaches to dealing with the heat problem before they settled on the size reduction and placement of the secondary coils. The high-temperature superconductors that are used in the ARC designs allow for smaller reactors but also make possible other options for optimizing the designs including the new diverter systems.
      This is just the beginning of the refinement and optimization of the new MIT ARC reactors. There will be further work to be done on fined the exact shape and placement of the secondary magnets that will yield the best results. Whyte says "This is opening up new paths in thinking about divertors and heat management in a fusion device."
       If nuclear fusion reactors can be created that actually generate more energy than they consume, they could have a major impact on the global energy industry. New nuclear fusion power plants that fuse elements such as hydrogen, helium, boron and/or lithium do not require toxic elements like uranium to fuel them. They also do not produce the toxic and long-lived nuclear wastes that are produced by nuclear fission reactors. They should be smaller and much less expensive to build and operate than nuclear fission reactors.
       The recent IPCC report says that we have only twelve years to reduce fossil fuel use by forty percent to forestall devastating climate change. By current estimates, commercial nuclear fusion power reactors will not be available within twelve years, so they cannot help with that goal. However, we will have to reduce fossil fuel use to zero in the next ten years. If we are lucky, nuclear fusion may be able to play a role then.