• Question: Based on the textbook for our course, my understanding is that the main drawback with fusion reactors is how much energy is required to heat the plasma. Do you think the solution for this come from finding ways to make the heating process more efficient, or more likely finding ways to release more energy from the fusion process? Can you give any examples of how scientists have improved the process or the reactors so far to make this more viable as an energy source?

    Asked by Katie S to Leah on 29 Mar 2020.
    • Photo: Leah Morgan

      Leah Morgan answered on 29 Mar 2020:


      Hi Katie, thanks for waiting! 🙂

      You are correct, the main problem with magnetically-confined fusion experiments (separate from inertial-confinement fusion) is that we create less energy than it took to run the experiment. It’s important to note here that we are talking about the reaction energy of the experiment – not electrical energy. That is, the energy created by the physics inside the machine. This ‘energy out’ is limited by the type of reaction we are doing and can’t be increased without changing the fuels we are using. Our highest energy output (at a temperature we can reach) is created while fusing deuterium and tritium – two hydrogen isotopes. Therefore, we must find more efficient ways to run our fusion devices (tokamaks).

      A lot of energy is lost through inefficient heating and cooling methods. For us at the Joint European Torus (JET), this is often due to ‘legacy’ material in the tokamak. This includes things like copper coils in our magnets which rapidly overheat and need to be cooled every time we run an experiment (a pulse).

      In the past, most improvements were made by plasma physicists to the fusion process itself. Now, advancements primarily happen in technological areas. Heating: we are working on developing heating technologies to create smaller and more efficient heating systems; at JET we need to reach temperatures of 150 million degrees! Recently we replaced all the protection tiles inside JET to test new materials for future tokamaks (like ITER which is being built in the south of France). We are also developing technologies linked to fusion like remote handling – which lets us send remote manipulators into fusion devices instead of people.

      Please send me more questions if you have them, thanks for your patience.

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