Reflections in gyrotrons with radial output: Consequences for the ITER coaxial gyrotron

Dumbrājs, O.; Nusinovich, Gregory S.; Piosczyk, B.

doi:10.1063/1.1810161

Cited by 11 publications

(2 citation statements)

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“…It could be caused by mode competition with the mode reflected. After the reflection, the wave goes through the cally predicted [26] and observed recently with a high-power 300 GHz gyrotron [27]. However, the power modulation could also be caused by a Fabry-Perot ef- fect between the experimental setup and the gyrotron window or by an electron beam instability.…”

Section: Stable Operating Pointmentioning

confidence: 63%

Study of the Effect of Reflections on High-Power, 110-GHz Pulsed Gyrotron Operation

Genoud

Picard

Schaub

et al. 2021

J Infrared Milli Terahz Waves

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The effect of reflection is studied experimentally and theoretically on a high-power 110 GHz gyrotron operating in the TE 22,6 mode in 3 µs pulses at 96 kV, 40 A. The experimental setup allows variation of the reflected power from 0 to 33 % over a range of gyrotron operating conditions. The phase of the reflection is varied by translating the reflector along the axis. Operating at a higher efficiency point, at 4.40 T with 940 kW of output power, reflected power exceeding 11% causes a switch from operation in the TE 22,6 to simultaneous operation in the TE 22,6 and TE 21,6 modes with a large decrease of the total gyrotron output power. This switching effect is in good agreement with simulations using the MAGY code. Operating at a more stable point, 4.44 T with 580 kW of output power, when the reflection is increased, the output power remains in the TE 22,6 mode but it decreases monotonically with increasing reflection, dropping to 200 kW at 33% reflection. Furthermore, at a reflection above 22%, a power modulation at 25 to 30 MHz is observed, independent of the phase of the reflected wave. Such a modulated signal may be useful in spectroscopic and other applications.

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