Abstract
An electron beam passing through a metamaterial structure is predicted to generate reversed Cherenkov radiation, an unusual and potentially very useful property. We present an experimental test of this phenomenon using an intense electron beam passing through a metamaterial loaded waveguide. Power levels of up to 5 MW are observed in backward wave modes at a frequency of 2.40 GHz using a one microsecond pulsed electron beam of 490 keV, 84 A in a 400 G magnetic field. Contrary to expectations, the output power is not generated in the Cherenkov mode. Instead, the presence of the magnetic field, which is required to transport the electron beam, induces a Cherenkov-cyclotron (or anomalous Doppler) instability at a frequency equal to the Cherenkov frequency minus the cyclotron frequency. Nonlinear simulations indicate that the Cherenkov-cyclotron mode should dominate over the Cherenkov instability at a lower magnetic field where the highest output power is obtained.
- Received 7 April 2016
DOI:https://doi.org/10.1103/PhysRevLett.117.237701
© 2016 American Physical Society
Physics Subject Headings (PhySH)
Focus
Better Microwaves from a Metamaterial
Published 2 December 2016
A system that produces radiation by sending electrons through a metamaterial waveguide could potentially generate high-power microwaves with high efficiency.
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