Near-ideal lasing with a uniform wiggler

Conference · Fri Jan 01 04:00:00 EST 1988

DOI:https://doi.org/10.1016/0168-9002(89)90417-8· OSTI ID:6659043

Warren, R W; Sollid, J E; Feldman, D W; Stein, W E; Johnson, W J; Lumpkin, A H; Goldstein, J C

Over the years the Los Alamos FEL team has reduced or eliminated many of the experimental problems that resulted in non-ideal lasing. The major problems were accelerator instabilities that cause noise and fluctuations in current, energy, and timing; wakefield effects in the wiggler and beamline that introduce fluctuations in the beam's energy; and mirror nonlinearities caused by free carriers produced in the mirror by the high light levels, which caused extra light losses and interfered with the diagnostics. Lasing is not thought to be ideal in that it lacks major disturbing effects and is limited only by emittance, energy spread, and peak current. In this paper we describe the features of lasing that we have observed over a range of optical power of 1000, from the onset of lasing, to the threshold of the sideband instability, to the organization of regular optical spikes, to the region of chaotic spikes. Cavity-length detuning is presented as an ideal technique, in most circumstances, to completely suppress sidebands. With detuning one can easily switch operating modes from that giving the highest efficiency (chaotic spiking) to that giving the narrowest spectral line (no sidebands). Alternative techniques for sideband suppression normally use some kind of wavelength selective device (e.g., a grating) inserted in the cavity. With detuning, there is no need for such a device, and, therefore, no conflict between the wavelength control exerted by this extra optical component and that exerted by the energy of the electron beam. Lasing, therefore, starts easily, a shift in wavelength, i.e., chirp, is easily accomplished, and the consequences of inadequate control of the electron beam energy are not severe. 35 refs., 16 figs.

• Research Organization: Los Alamos National Lab., NM (USA)
• DOE Contract Number: W-7405-ENG-36
• OSTI ID: 6659043
• Report Number(s): LA-UR-88-3586; CONF-8808146-10; ON: DE89003465
• Country of Publication: United States
• Language: English

Related Subjects

42 ENGINEERING
420300* -- Engineering-- Lasers-- (-1989)
BEAM EMITTANCE
DESIGN
EFFICIENCY
ELECTRICAL EQUIPMENT
ELECTROMAGNETS
ENERGY SPECTRA
EQUIPMENT
FLUCTUATIONS
FREE ELECTRON LASERS
LASERS
MAGNETS
SPECTRA
VARIATIONS
WIGGLER MAGNETS