CNC Machined Helically Corrugated Interaction Region for a THz Gyrotron Traveling Wave Amplifier

et al. 2020

TST

The gyrotron travelling wave tube amplifiers (gyro-TWAs) presented in this paper can operate with high efficiency (30%), huge powers and wide bandwidths at high frequencies that no other amplifier can provide. In principle, this is a technology that can be scaled to >1 THz and operate with 20% bandwidths. Resonant coupling of two dispersive waveguide modes in a helically corrugated interaction region (HCIR) can give rise to a non-dispersive eigenwave over a wide frequency band. The synchronism between the ideal wave and an electron cyclotron mode, either fundamental or harmonic, of a large orbit electron beam contributes to the broadband amplification. An electron beam of 55 keV, 1.5 A with a velocity pitch angle of ~1 generated by a thermionic cusp gun is used in our 100 GHz gyro-TWA experiment, which achieves an unsaturated output power of 3.4 kW and gain of 36–38 dB. The design and experimental results of the many components making the gyro-TWA will be presented individually and then the whole system will be introduced. The amplification of a swept signal by the W-band gyro-TWA is demonstrated showing its capabilities in the field of telecommunications. Furthermore, the design studies of a cusp electron gun in the triode configuration and the realization of a 3-fold HCIR operating at 372 GHz will also be displayed.

Section: Further Developmentsmentioning

confidence: 99%

The Development of broadband millimeter-wave and terahertz gyro-TWAs

et al. 2020

TST

“…While experiments have been reported up to W-band, at higher frequencies the HCIR is technically challenging due to the need to maintain the Ohmic loss at a tolerable level and the difficulty of machining the part. However, it is possible to design and construct a 0.372 THz HCIR based on a 3-fold (3F) configuration [15]. State-of-theart manufacturing facilities were required to build the 23.8 mm long 3F HCIR with an average diameter of 0.7 mm.…”

Section: Introductionmentioning

confidence: 99%

8-Fold Helically Corrugated Interaction Region for High Power Gyroresonant THz Sources

IEEE Electron Device Lett.

Harris

et al. 2021

Self Cite

A manufacturing study of a 0.372 THz 8-fold (8F) helically corrugated interaction region (HCIR) and measurement of its wave dispersion characteristics are reported. This demonstrates the structure's suitability as the electron beam / electromagnetic wave interaction region in a high power frequency tunable Gyroresonant THz source. The 8F HCIR has an eigenmode, which is ideal for broadband tuning, created by the coupling of the TE 61 and TE 23 modes. Maximum power handling of 14 times larger than a 3-fold HCIR at the same frequency is calculated. A TE 11 to TE 61 7-fold (7F) helically corrugated waveguide (HCW) mode converter, needed to measure the wave dispersion of the 8F HCIR, was designed and constructed. Negative aluminium mandrels of the 7F HCW mode converter and 8F HCIR were manufactured. Copper structures were constructed through electroforming. The measured wave dispersion of the 0.372 THz 8F HCIR agreed well with simulated dispersion characteristics.

“…Based on this design, a gyro-TWA operating centrally at 372 GHz with 5% bandwidth is being developed. Similarly the beam-wave interaction will be driven by a cusp electron gun with a HCIR [6]. Further components will be required including input coupler [7] with a pillbox window [8], polarizer [9], and an output coupler, which will be the topic of this paper.…”

Section: Introductionmentioning

confidence: 99%

Output coupler for a THz gyro-amplifier

2019 International Vacuum Electronics Conference (IVEC)

2019

Self Cite

This paper presents the design and simulation results of an output coupler for a gyro-amplifier operating at THz frequencies. The combination of a smoothly profiled horn and multilayer microwave window allow for the almost total conversion of the TE11 mode to the Gaussian-like HE11 mode while forming a vacuum tight seal with very low reflections. This assembly operates over the 360-384 GHz frequency range.