Emittance studies at the Los Alamos National Laboratory Free-Electron Laser

Conference · Thu Jan 01 00:00:00 EST 1987

DOI:https://doi.org/10.1016/0168-9002(88)90232-X· OSTI ID:5673149

Carlsten, B E; Feldman, D W; Lumpkin, A H; Stein, W E; Warren, R W

Recent emittance studies at the Los Alamos FEL have indicated several areas of concern in the linac and beamline feeding the wiggler. Four emittance growth mechanisms of special importance have been studied. First, a rapid growth of the electron beam's emittance immediately after the spherical gridded Pierce gun resulted, in part, from the long time required for our pulsing electronics to ramp the grid voltage up at the start and down at the end of the pulse, which created a pulse with a cosine-like current distribution as a function of time. The growth was compounded by the extremely small radial beam size (almost a waist) leaving the gun. In addition, we saw evidence of electrostatic charging of the insulators in the gun, reducing the quality of the electron beam further. Second, the action of the solenoidal focusing fields in the low-voltage bunching region was studied, and criteria for a minimum emittance growth were established. Third, maximum misalignment angles and displacements for various elements of the beamline were calculated for the desired low emittance growth. Finally, emittance growth in the horizontal dimension through the nonisochronous bend caused by varying energy depression on the particles due to longitudinal wake fields was both calculated and observed. In addition, we measured energy depressions caused by the wake fields generated by various other elements in the beamline. Strategies were developed to relieve the magnitude of these wake-field effects. 10 refs., 12 figs.

• Research Organization: Los Alamos National Laboratory (LANL), Los Alamos, NM (United States)
• DOE Contract Number: W-7405-ENG-36
• OSTI ID: 5673149
• Report Number(s): LA-UR-87-3046; CONF-8709110-13; ON: DE88003146
• Resource Relation: Journal Volume: 272; Journal Issue: 1-2; Conference: 9. international free-electron laser conference, Williamsburg, VA, USA, 14 Sep 1987; Other Information: Portions of this document are illegible in microfiche products
• Country of Publication: United States
• Language: English

Related Subjects

43 PARTICLE ACCELERATORS
42 ENGINEERING
FREE ELECTRON LASERS
BEAM EMITTANCE
BEAM BENDING MAGNETS
BEAM BUNCHING
BEAM CURRENTS
COMPUTERIZED SIMULATION
ELECTRON BEAMS
ELECTRON GUNS
ERRORS
EXPERIMENTAL DATA
PHASE SPACE
BEAM DYNAMICS
BEAMS
CURRENTS
DATA
ELECTRICAL EQUIPMENT
ELECTROMAGNETS
EQUIPMENT
INFORMATION
LASERS
LEPTON BEAMS
MAGNETS
MATHEMATICAL SPACE
NUMERICAL DATA
PARTICLE BEAMS
SIMULATION
SPACE
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Field Calculations
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