Obtaining and maintaining adequate plasma is one of the challenges to overcome in order to harness the enormous amounts of energy provided by nuclear fusion.
Plasmas (“ultrahot soups” of ions and electrons) must be maintained at the proper density, temperature, and duration for atomic nuclei to fuse and the desired release of energy to occur.
One of the recipes for achieving these conditions is to use large donut-shaped devices, equipped with powerful magnets, that contain a plasma while carefully aligned microwave generators heat the atomic mixture.
Now, the Institute for Advanced Energy at Kyoto University in Japan, the Kharkiv Institute of Physics and Technology in Ukraine, and the Max Planck Institute for Plasma Physics in Germany have collaborated to create, using microwaves, plasmas with stabilities and densities suitable for nuclear fusion reactors.
This line of research and development is carried out using the Heliotron J, an experimental plasma fusion device from the Advanced Energy Institute.
During one of the experiments with the Heliotron J, Yurii Victorovich Kovtun, Kazunobu Nagasaki and their colleagues were surprised to discover that plasmas without cyclotron resonance formed.
The team injected intense 2.45 GHz microwave bursts into a gas. Household microwave ovens operate at this same frequency, but the Heliotron J is about 10 times more powerful and concentrates on just a few gas atoms. Unexpectedly, the researchers discovered that firing the microwaves without aligning the Heliotron J’s magnetic field created a discharge that ripped electrons from their atoms and produced an especially dense plasma.
General structure of the Heliotron J. (Image: Kyoto U / Heliotron J group)
The research team exposes the technical details of their latest experiments in the academic journal Problems of Atomic Science and Technology, under the title “Non-Resonant Microwave Discharge Start-Up in Heliotron J”. (Fountain: NCYT by Amazings)