Gyrotron

From Wikipedia, the free encyclopedia

Gyrotrons are high powered electron tubes which emit a millimeter wave beam by bunching electrons with cyclotron motion in a strong magnetic field. Typical output powers range from 10s of kilowatts to 1-2 megawatts. Output frequencies range from about 20 to 250 GHz. Gyrotrons can be designed for pulsed or continuous operation. Gyrotron manufacturers include CPI (USA), Gycom (Russia), Thales Group (EU), and Toshiba (Japan). A prevalent application of gyrotrons is as a source of plasma heating in nuclear fusion research experiments.

The gyrotron is a type of free electron maser (microwave amplification by stimulated emission of radiation). It has high power at millimeter wavelengths because its dimensions can be much larger than the wavelength, unlike conventional vacuum tubes, and it is not dependent on material properties, as are conventional masers. The bunching depends on a relativistic effect called the Cyclotron Resonance Maser instability. The electron speed in a gyrotron is slightly relativistic (comparable to but not close to the speed of light). This contrasts to the free electron laser (and xaser) that work on different principles and whose electrons are highly relativistic.