These are ~100 GHz generators of High-power RF. They rely on High-temperature superconducting magnets. The resonant frequency is the magnetic field x 28, so that 1 Tesla field leads to a 28 GHz RF source.
According to Jagadishwar (Jag) Sirigiri from Bridge 12, commercial gyrotrons for fusion:
- Can generate 1 MW at 170 GHz with 50% efficiency
- Main failure mode is the lifetime of the collector (~10k shots)
- The main limitations come from cooling the cavity and collector, and thermal stresses
- Frequencies are limited by magnet cost. Can’t go beyond 170 GHz with NbSn.
MIT technological capabilities related to gyrotrons include:
There may be new applications to gyrotrons (see New commercial applications of gyrotrons (WIP)).
It may also be possible to develop a High-powered gyrotron for fusion thanks to advances in magnet technology. Related would be a Better gyrotron for geothermal drilling.
Major vendors
- Bridge 12
- Kyoto Fusioneering
- Forschungszentrum Karlsruhe
- Others…
Challenges today
- Efficiency of gyrotrons and klystrons (currently only 30-40%)
- Lifetimes: Right now, gyrotrons burn out after a few hours of total use.