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Electron Cyclotron Resonance Heating

60 GHz-300 kW Gyrotron General Design for the Mexican Tokamak "T"

Gyrotron scheme

We present the preliminary design of our source for ECRH system applied in our Tokamak "T" device, a gyrotron device 60 GHz-300 kW which is currently developed by the Fusion Research Group at the Nuevo Leon State University (UANL, Spanish acronyms) in Monterrey, Mexico.

A gyrotron is a source of coherent elec-tromagnetic radiation capable of providing hundreds of kilowatts of power in regions with millimeter and sub-millimeter wavelength.

This power generated either continuous wave (CW) or long pulse, oscillates between 0.1 - 1 MW. In this device, a magnetron injection gun (MIG) is used to generate a gyrating electron beam, then, it interacts whit the eigen-mode of a cavity transforming part of the kinetic energy into the microwave energy.

A) MIG magnetic coil; B) principal magnetic coils; C) MIG; D) beam tunnel; E) cavity; F) window; G) collector; H) collector coil

The design of the MIG requires an optimized electron beam analysis. For this purpose, a theory based on the conservation of the angular momentum and the adiabatic electron motion is regularly used. As a first step in our gyrotron design, we present an array of four copper coils achieving a maximum configuration of magnetic intensity of 2.56 T, required into the cavity to arise 60 GHz high-power millimeter frequency in the fundamental harmonic, in addition to the nominal beam parameters such as interaction region to cathode ratio of a magnetic
compression of 13.68; a beam voltage of 100 kV, a beam current of 3 A, and transverse to axial velocity ratio of 1.5, were established. An initial design has been obtained, from analytical adiabatic trade-off equations by Baird and Lawson, of a diode type magnetron injection gun characterizing our trajectory parameters beam in the Tokamak "T" gyrotron.

The mean radius of the emitter (7.3 mm), slant length of the emitting surface (8.8 mm), cathode modulating anode gap (11.5 mm), slope angle of emitter (40) are obtained. These results are supported by 2D computer simulations

Gyrotron Design

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