Design, Test and Analysis of a Gyrotron Cavity Mock-Up Cooled Using Mini Channels

In 2016, we have designed, built, and finally tested at the FE200 facility in Le Creusot, France, a planar mock-up mimicking the water-cooled cylindrical resonance cavity of the European 170-GHz, 1-MW gyrotron to be used for electron cyclotron plasma heating in ITER. The aim of the mock-up is the characterization of the cooling capability of the cavity. A Glidcop target is heated with an electron beam gun with resulting peak heat fluxes relevant for the full-size cavity. Underneath the target surface, whose temperature is monitored by means of a pyrometer, a set of parallel semicircular mini channels, with a diameter of 1.5 mm, allow the flow of pressurized water, entering the mock-up at
_~
9 bar and 40 °C. Several thermocouples measure the target temperature, at different distances from the heated target surface. The experimental results show that the mock-up is capable to withstand heat fluxes of 21 MW/m
²
, while the cooling system keeps the heated surface below
_~
400 °C, for flow conditions comparable to those of the full-size cavity. The test results are used to first calibrate the uncertain model parameters and then, with frozen parameters, to validate a previously developed computational fluid dynamics model, showing good agreement with the experiment. In view of its reliability, this model might eventually be a useful tool for the simulation of the full-size gyrotron cavity operation.