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

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 bothmore » 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.« less
Authors:
; ; ; ;
Publication Date:
OSTI Identifier:
5673149
Report Number(s):
LA-UR-87-3046; CONF-8709110-13
ON: DE88003146
DOE Contract Number:
W-7405-ENG-36
Resource Type:
Conference
Resource Relation:
Conference: 9. international free-electron laser conference, Williamsburg, VA, USA, 14 Sep 1987; Other Information: Portions of this document are illegible in microfiche products
Research Org:
Los Alamos National Lab., NM (USA)
Country of Publication:
United States
Language:
English
Subject:
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 430200* -- Particle Accelerators-- Beam Dynamics, Field Calculations, & Ion Optics; 420300 -- Engineering-- Lasers-- (-1989)