Title :
Measurement and optimization of the VISA undulator
Author :
Rakowsky, G. ; Aspenleiter, J. ; Solomon, L. ; Car, R. ; Ruland, R. ; Lidia, S.
Author_Institution :
Brookhaven Nat. Lab., Upton, NY, USA
Abstract :
The Visible-Infrared SASE Amplifier (VISA) undulator is an in-vacuum, 4-meter long, 1.8 cm period, pure-permanent magnet device, with a novel, strong focusing, permanent magnet FODO array included within the fixed, 6 mm undulator gap. The undulator magnet is constructed of 99-cm long segments, joined into a continuous structure. To attain maximum SASE gain requires establishing overlap of electron and photon beams to within 50 microns rms. This imposes challenging tolerances on mechanical fabrication and magnetic field quality, and necessitates use of laser straightness interferometry for calibration and alignment of the magnetic axes of the undulator segments. This paper describes the computerized magnet sorting, pulsed-wire magnetic measurements, trajectory shimming and magnetic axis calibration performed to meet this goal
Keywords :
calibration; permanent magnets; superradiance; wigglers; VISA undulator; Visible-Infrared SASE Amplifier undulator; computerized magnet sorting; laser straightness interferometry; magnetic axis calibration; magnetic field quality; mechanical fabrication; permanent magnet FODO array; pulsed-wire magnetic measurements; pure-permanent magnet device; trajectory shimming; undulator gap; undulator magnet; undulator segments; Calibration; Electron beams; Interferometry; Laser beams; Magnetic devices; Magnetic field measurement; Optical device fabrication; Permanent magnets; Sorting; Undulators;
Conference_Titel :
Particle Accelerator Conference, 1999. Proceedings of the 1999
Conference_Location :
New York, NY
Print_ISBN :
0-7803-5573-3
DOI :
10.1109/PAC.1999.792908
