Periodically corrugated waveguides for slow-wave THz free-electron laser
We investigate a slow-wave THz free-electron laser consisting of axially or helically corrugated waveguides driven by an annular electron beam. When the device is driven by a 10-mA electron beam at 30 keV, we numerically demonstrated backward-wave oscillation at 0.2212 and 0.2651 THz in axially and...
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| Main Authors: | , , |
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| Format: | Article |
| Language: | English |
| Published: |
American Physical Society
2025-04-01
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| Series: | Physical Review Accelerators and Beams |
| Online Access: | http://doi.org/10.1103/PhysRevAccelBeams.28.040701 |
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| Summary: | We investigate a slow-wave THz free-electron laser consisting of axially or helically corrugated waveguides driven by an annular electron beam. When the device is driven by a 10-mA electron beam at 30 keV, we numerically demonstrated backward-wave oscillation at 0.2212 and 0.2651 THz in axially and helically corrugated waveguides, respectively, without a solenoid field within a submillimeter aperture. We developed a unified theoretical framework for the two types of waveguides and successfully explained the observed backward-wave resonances. In our theory, azimuthal-symmetry breaking in a helically corrugated waveguide couples the synchronous transverse-magnetic radiation mode to a transverse-electric mode, resulting in radiation loss for the oscillation. Therefore, this study concludes superior radiation performance for the axially corrugated waveguide as a slow-wave THz free-electron laser. Furthermore, we show the opportunity of exciting self-started cyclotron resonance maser oscillations at THz frequencies from a helically corrugated waveguide without a solenoid field. |
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| ISSN: | 2469-9888 |