Design of 95 GHz gyrotron based on continuous operation copper solenoid with water cooling

Abstract

The design work for 2nd harmonic 95 GHz, 50 kW gyrotron based on continuous operation copper solenoid is presented. Thermionic magnetron injection gun specifications were calculated according to the linear trade off equation, and simulated with CST program. Numerical code is used for cavity design using the non-uniform string equation as well as particle motion in the "cold" cavity field. The mode TE02 with low Ohmic losses in the cavity walls was chosen as the operating mode. The Solenoid is designed to induce magnetic field of 1.8 T over a length of 40 mm in the interaction region with homogeneity of ±0.34%. The solenoid has six concentric cylindrical segments (and two correction segments) of copper foil windings separated by water channels for cooling. The predicted temperature in continuous operation is below 93 °C. The parameters of the design together with simulation results of the electromagnetic cavity field, magnetic field, electron trajectories, and thermal analyses are presented.

The design of the gyrotron magnetic system

“…To obtain a proper magnetic field profile, hybrid solenoids are used [6]. In many approaches superconducting magnets are used [6], but other solutions are also explored such as permanent magnets [7], [8], warm superconducting magnets [9] and classical coper solenoids [10].…”