Ultra-short pulse prebunched FEL
- Univ. of California, Los Angeles, CA (United States). Electrical Engineering Dept.
- Univ. of California, Davis, CA (United States)
- Lawrence Livermore National Lab., CA (United States)
Currently under design is an X-band photocathode linac FEL system which produces picosecond, MW-power pulses of coherent microwave and millimeter-wave radiation. In this system, the resultant electron bunches are considerably shorter than the wavelength of the emitted radiation, and these bunches coherently emit synchrotron radiation in the wiggler interaction region to generate subnanosecond, millimeter-wave MW pulses. The output radiation pulse length is essentially determined by the slippage between the electron bunch and the electromagnetic waves through the wiggler. The wiggler produces a 5 kG helically polarized field, with an 84 mm period over a length of 2 meters. With 1 nC, 4 MeV, 3.3 ps FWHM electron bunches, this wiggler produces 35 GHz pulses with peak power levels in excess of 100 kW, and with pulse durations of ca. 100 ps for the grazing interaction. The device operates in the fundamental TE{sub 11} cylindrical waveguide mode. Close to grazing, where slippage is minimal, the pulses are further compressed because of the very wide instantaneous interaction bandwidth. In this regime, the output pulse duration is determined by the group velocity dispersion in the waveguide and the interaction bandwidth. In the planned upgrade for the system, 10 MeV photoelectron bunches produced by the X-band RF photocathode linac will be propagated through a 3 m-long, 10 kG, 40 mm-period, helically polarized wiggler magnetic field to generate more than 2 MW of 220 GHz radiation at grazing. The cylindrical interaction waveguide will operate on the TE{sub 12} mode. In the current phase of the program, a 100 fs, 100 mJ Ti:Sapphire laser system with 5 ps jitter is used to produce electron bunches. The next phase of the program includes the use of a synchronously driven, quantum well saturable absorber mode locked AlGaAs oscillator and amplifier system, which has produced 210 fsec duration pulses with a relative timing jitter of ca. 400 fsec.
- OSTI ID:
- 51866
- Report Number(s):
- CONF-940142-; ISBN 0-8194-1449-2; TRN: IM9524%%336
- Resource Relation:
- Conference: OE/LASE `94: conference on optics, electro-optics, and laser applications in science and engineering, Los Angeles, CA (United States), 22-29 Jan 1994; Other Information: PBD: 1994; Related Information: Is Part Of Intense microwave pulses II. SPIE Volume 2154; Brandt, H.E. [ed.]; PB: 421 p.
- Country of Publication:
- United States
- Language:
- English
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