Mesa+, Enschede
* Proceedings of the 2004 FEL Conference, Trieste, Italy, 2004, p314-317** J. Appl. Phys. 100, 053108 (2006)
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| MOAAU02 | Lasing of a Cherenkov FEL Driven by a Low Electron Beam Current | |
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We have designed and constructed a compact (0.5 x 1.5 m), 100 kV Cerenkov FEL operating at around 20 to 25 GHz*. The electron beam is produced by a gridded thermionic electron gun, which yields a maximum current of about 500 mA. This current is injected into a cylindrical waveguide lined with Al2O3 and about 60 % of the beam is transported through the lined waveguide section. A transported current of only 250 mA was sufficient to observe lasing. The total power generated for an interaction length of 25 cm was about 3 W. Although not designed as an oscillator, reflections at various positions along the waveguide provide a low-Q resonator. The power observed was in good agreement with results obtained with a model of the CFEL when reasonable values are used for beam quality, resonator feedback and liner fluctuations**. Measurement of the tuning with voltage showed excellent agreement with theory, and indicates operation at the fundamental TM01 mode as well as on higher order modes.
* Proceedings of the 2004 FEL Conference, Trieste, Italy, 2004, p314-317** J. Appl. Phys. 100, 053108 (2006) |
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