The German fusion reactor, Wendelstein-7X, has achieved a milestone in the energy conversion of fusion plasma. The reactor ran for eight minutes at 1.3 gigajoules, setting a new record for discharge duration and heating power. Wendelstein-7X is the world’s largest stellarator reactor, and its concept for constructing power plants has been deemed suitable by a study from the Max-Planck-Institut für Plasmaphysik (IPP). The reactor uses a ring of 50 superconducting magnet coils to hold the ultra-hot fusion plasma in place, and unlike Tokamak reactors, it can theoretically run continuously. Wendelstein-7X began experiments in 2015, and after a three-year upgrade, it has doubled its plasma input. Recently, physicists at the German fusion reactor have measured a new milestone, reaching an energy conversion of 1.3 gigajoules, surpassing its old record by 17 times.
To achieve the 1.3 gigajoules, a three-part plasma heating system was used. The first part is a neutral particle injection, where accelerated hydrogen atoms are shot into the plasma, causing collisions that heat it up. The second heating method uses radio waves to make the ions in the plasma vibrate and heat up, similar to a microwave. The last heating method, a microwave electron heating, heats the plasma’s electrons through vibrations. The microwave electron heating is crucial for fusion energy conversion because it can transfer large amounts of energy for several minutes. The innovative plasma heating system and wall cooling in the fusion reactor are essential for Wendelstein-7X’s operation. The reactor’s wall cooling system consists of 120 new divertor modules with a cooling system and 657 cooling circuits that dissipate the plasma’s heat.
The Wendelstein-7X team aims to increase the energy conversion to 18 gigajoules and stabilize the plasma for 30 minutes in the coming years. Physicists must proceed step by step to avoid overloading and damaging the reactor. Wendelstein-7X’s achievement is a significant step towards achieving sustainable energy through fusion power. The reactor’s innovative design and plasma heating system could pave the way for future fusion power plants.
