Abstract
In this paper, the collimation characteristics of an electron cyclotron resonance heating (ECRH)
system with a 28GHz/50kW gyrotron in EXL-50 are studied experimentally. Through using laser trackers
and designing matching tooling, test errors of horizontal distances and vertical distances between the
transmission line and the flange center are all within 1mm, which are less than 0.4% and 0.07% respectively.
In addition, online beam spot test with a 150 ms short pulse from a 28 GHz gyrotron also proves good
collimation characteristics of the ECRH system. Finally, spherical plasma is formed through injecting the
microwave to the vacuum chamber.