Antonio C. Torrezan, Michael A. Shapiro
The design and operation of a frequency tunable continuous-wave (CW) 330-GHz gyrotron oscillator operating at the second harmonic of the electron cyclotron frequency are reported. The gyrotron has generated 18 W of power from a 10.1-kV 190-mA electron beam working in a TE-4,3 cylindrical mode, corresponding to an efficiency of 0.9%. The measured start oscillation current over a range of magnetic field values is in good agreement with theoretical start currents obtained from linear theory for successive high order axial modes TE-4,3,q, where q = 1 to 6. The observed frequency range in the start current measurement is in reasonable agreement with the frequency range calculated from numerical simulations. The minimum start oscillation current of the device was measured to be 33 mA. A continuous tuning range of 1.2 GHz was observed experimentally via a combination of magnetic, voltage, and thermal tuning. The gyrotron output power and frequency stabilities were assessed to be ±0.4% and ±3 ppm, respectively, during a 110-hour uninterrupted CW run. Evaluation of the gyrotron microwave output beam pattern using a pyroelectric camera indicated a Gaussian-like mode content of 92% with an ellipticity of 28%. The gyrotron will be used for 500-MHz nuclear magnetic resonance (NMR) experiments with sensitivity enhanced by dynamic nuclear polarization (DNP).
@article{bbf28df8-0254-4822-aa7c-4423e9572560,
title={Operation of a Continuously Frequency Tu},
author={Antonio C. Torrezan and Michael A. Shapiro},
year={2026},
language={en}
}TY - JOUR TI - Operation of a Continuously Frequency Tu AU - Antonio C. Torrezan AU - Michael A. Shapiro PY - 2026 LA - en ER -
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