35-GHz 25-kW CW low-voltage third-harmonic gyrotron

McDermott, D.B.; Balkcum, Adam; Luhmann, Neville C.

doi:10.1109/27.532944

Cited by 13 publications

(4 citation statements)

References 27 publications

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“…Recently gyro-devices have begun to adopt cusp guns as their electron beam sources notably in lower frequency harmonic gyro-devices (McDermott et al, 1996). A cold cathode cusp gun was developed for an X-Band gyro-TWA at the University of Strathclyde in 2007 (Cross et al, 2007).…”

Section: Previous Research On Cusp Electron Gunsmentioning

confidence: 99%

Numerical Simulations of Physical and Engineering Processes

2011

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The gyrotron backward wave oscillator (gyro-BWO) is an efficient source of frequency-tunable high-power coherent radiation in the microwave to the terahertz range. It has attracted significant research interest recently due to its potential applications in many areas such as remote sensing, medical imaging, plasma heating and spectroscopy. A gyro-BWO using a helically corrugated interaction region (HCIR) has achieved an even wider frequency tuning range and higher efficiency compared with a conventional gyro-BWO with a smooth-bore cavity. This is due to the existence of an "ideal"eigenwave in the HCIR with a large and constant group velocity when the axial wave number is small. The eigenwave has a TE 21-like cross-sectional electric field distribution. For such a field structure it is favourable to use the second harmonic of the electron cyclotron frequency of an axis-encircling electron beam to interact with the wave. The advantage being that it lowers the required magnetic field strength by a factor of two whilst avoiding undesired parasitic oscillations. Therefore a cusp gun was used to produce an annular, axis-encircling electron beam with high velocity ratio, α (ratio of transverse velocity to axial velocity) for the gyro-BWO. This has inherent advantages over a solid beam for energy recovery due to the reduced beam power density in the collector surface making high power (∼ kWs) continuous wave (CW) operation of a gyro-BWO more feasible. The overall efficiency of the gyro-BWO is further improved by using a four-stage depressed collector which recovers the energy from the spent electrons of the gyro-BWO. The 3D particle-in-cell (PiC) code MAGIC was used to simulate the electron beam trajectories, beam-wave interaction and wave growth in the gyro-BWO. The trajectories of the electrons were simulated including their emission from the cathode, acceleration in the cusp gun region, transportation and interaction in the helical interaction region and deceleration in the depressed collector. Through the simulations a thermionic cusp electron gun was optimized to produce a 40 keV, 1.5 A, large-orbit, electron beam with an axial velocity spread Δv z /v z of ∼8% and a relative α spread Δα/α of ∼10% at an α value of 1.65. When driven by such a beam the gyro-BWO was simulated to have a 3 dB frequency bandwidth of 84-104 GHz, output power of 10 kW with an electronic efficiency of 17%. The optimization of the shape

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Section: Previous Research On Cusp Electron Gunsmentioning

confidence: 99%

Numerical Simulations of Physical and Engineering Processes

2011

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“…The operation at the high harmonics relaxes not only the requirement of large magnetic field but also weakens beam-wave interaction and increase start oscillation current, and hence permitting large beam currents for the high-power and stable operation of the gyro-TWT [2], [3], [11]- [14]. However, it has also been recognized that high-cyclotron harmonic operation would require an electron beam with high-beam energy [11], [12].…”

Section: Introductionmentioning

confidence: 97%

Gain and Bandwidth Analysis of a Vane-Loaded Gyro-TWT

Singh

Kartikeyan

Park

2006

Int J Infrared Milli Waves

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Theoretical investigation of the peak-gain and 3-dB bandwidth of the vane-loaded gyro-traveling wave tube (gyro-TWT) amplifier in the small-orbit TE 01 waveguide mode configuration at 35 GHz has been presented. The vane-loaded gyro-TWT enjoys higher gain and bandwidth compared to that of the smooth-wall device. In the analysis, the azimuthal harmonic effects generated due to the angular periodicity of vanes in the wedge-shaped metal vane-loaded cylindrical waveguide interaction structure have been taken into account in the cold (beam-absent) dispersion relation only.

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“…There has been much discussion and many experiments regarding cyclotron devices, for instance, gyrotron oscillators and amplifiers, at harmonics of the cyclotron frequency [2]- [4]. Also, free particle cyclotron emission can occur at the harmonics as well [5].…”

Section: Introductionmentioning

confidence: 99%

On the possibility of harmonic operation of cyclotron wave parametric amplifiers

Manheimer

1997

IEEE Trans. Plasma Sci.

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Cyclotron wave amplifiers at the harmonics of the electron cyclotron frequency are investigated. Since the waves on the beam are electrostatic, harmonics are strongly excited in nonrelativistic beams if they are rotating rather than filamentary. These modes at the harmonics can couple to input Cuccia couplers, and pump fields which drive parametric amplification, in very much the same way as they do on filamentary beams at the cyclotron frequency. Harmonic cyclotron wave amplifiers have the possibility of giving rise to a new class of devices at millimeter wave frequencies.

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35-GHz 25-kW CW low-voltage third-harmonic gyrotron

Cited by 13 publications

References 27 publications

Numerical Simulations of Physical and Engineering Processes

Numerical Simulations of Physical and Engineering Processes

Gain and Bandwidth Analysis of a Vane-Loaded Gyro-TWT

On the possibility of harmonic operation of cyclotron wave parametric amplifiers

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