Efficiency and sideband observations of a Raman FEL oscillator with a tapered undulator

Journal Article · Fri Apr 01 04:00:00 EST 1988 · IEEE Trans. Plasma Sci.; (United States)

DOI:https://doi.org/10.1109/27.3809· OSTI ID:7126955

Yee, F G; Marshall, T C; Schlesinger, S P

Power and spectral measurements are reported from the Columbian Raman free-electron laser (FEL) oscillator experiment. High-power radiation pulses (-- 12 MW, 100 ns) are generated to a wavelength of -- 2.5 mm, using a 750-kappaV electron beam injected into a helical undulator; the latter is made up of a constant-period (1.45 cm) section 40 cm long followed by an equal length of tapered undulator. The period is decreased by 7.6 percent in such a way that the on-axis field remains constant. The authors find that the taper allows an increase in total power efficiency from -- 4 to -- 12 percent. Most noteworthy is that the tapered undulator reduces the sideband radiation compared with a constant-period undulator FEL which was studied in the same configuration. The power was measured calorimetrically and compared with the results of a 1-D Raman code. The reduction of sideband power observed in the experiment was consistent with computational results obtained with a 2-D sideband code.

• Research Organization: Dept. of Applied Physics, Columbia Univ., New York, NY (US)
• OSTI ID: 7126955
• Journal Information: IEEE Trans. Plasma Sci.; (United States), Journal Name: IEEE Trans. Plasma Sci.; (United States) Vol. 16:2; ISSN ITPSB
• Country of Publication: United States
• Language: English

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BEAM INJECTION
BEAMS
CALORIMETRY
COMPUTER CALCULATIONS
COMPUTER CODES
CONFIGURATION
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ELECTROMAGNETS
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MAGNETS
MEASURING METHODS
NUMERICAL DATA
ONE-DIMENSIONAL CALCULATIONS
PARTICLE BEAMS
POWER SUPPLIES
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SPECTRA
WIGGLER MAGNETS