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Title: Emittance Measurements of the SSRL Gun Test Facility

Abstract

A photocathode RF gun test stand is under construction in the injector vault of the Stanford Synchrotron Radiation Laboratory at SLAC. The goal of this facility is to produce an electron beam with a normalized emittance of 1-3[mm-mr], a longitudinal bunch duration of the order of 10[ps] FWHM and approximately 1[nC] of charge per bunch. The beam will be generated from a laser driven copper photocathode RF gun developed in collaboration with BNL, LBL and UCLA. The 3-5[MeV] beam from the gun will be accelerated using a SLAC three meter S-band accelerator section. The emittance of the electron beam will be measured through the use of quadrupole scans with phosphor screens and also a wire scanner. The details of the experimental setup will be discussed, and first measurements will be presented and compared with results from PARMELA simulations.

Authors:
; ; ; ; ; ; ; ; ; ; ; ; ; ;
Publication Date:
Research Org.:
SLAC National Accelerator Lab., Menlo Park, CA (United States)
Sponsoring Org.:
USDOE
OSTI Identifier:
1023790
Report Number(s):
SLAC-REPRINT-2011-040
TRN: US1105068
DOE Contract Number:
AC02-76SF00515
Resource Type:
Conference
Resource Relation:
Journal Name: Conf.Proc.C970512:2840,1997; Conference: 17th IEEE Particle Accelerator Conference (PAC 97): Accelerator Science, Technology and Applications, 12-16 May 1997, Vancouver, British Columbia, Canada
Country of Publication:
United States
Language:
English
Subject:
43 PARTICLE ACCELERATORS; BEAM BUNCHING; BEAM EMITTANCE; COMPARATIVE EVALUATIONS; CONSTRUCTION; ELECTRON BEAMS; ELECTRON GUNS; MEETINGS; MEV RANGE 01-10; PHOSPHORS; PHOTOCATHODES; QUADRUPOLES; RF SYSTEMS; STANFORD LINEAR ACCELERATOR CENTER; SYNCHROTRON RADIATION; Accelerators,ACCSYS

Citation Formats

Hernandez, Michael, Clendenin, James, Fisher, Alan, Miller, Roger, Palmer, Dennis, Park, Sam, Schmerge, John, Weaver, Jim, Wiedemann, Helmut, Winick, Herman, Yeremian, Dian, /SLAC, Meyerhofer, David, Reis, David, and /Rochester U. Emittance Measurements of the SSRL Gun Test Facility. United States: N. p., 2011. Web.
Hernandez, Michael, Clendenin, James, Fisher, Alan, Miller, Roger, Palmer, Dennis, Park, Sam, Schmerge, John, Weaver, Jim, Wiedemann, Helmut, Winick, Herman, Yeremian, Dian, /SLAC, Meyerhofer, David, Reis, David, & /Rochester U. Emittance Measurements of the SSRL Gun Test Facility. United States.
Hernandez, Michael, Clendenin, James, Fisher, Alan, Miller, Roger, Palmer, Dennis, Park, Sam, Schmerge, John, Weaver, Jim, Wiedemann, Helmut, Winick, Herman, Yeremian, Dian, /SLAC, Meyerhofer, David, Reis, David, and /Rochester U. Thu . "Emittance Measurements of the SSRL Gun Test Facility". United States. doi:.
@article{osti_1023790,
title = {Emittance Measurements of the SSRL Gun Test Facility},
author = {Hernandez, Michael and Clendenin, James and Fisher, Alan and Miller, Roger and Palmer, Dennis and Park, Sam and Schmerge, John and Weaver, Jim and Wiedemann, Helmut and Winick, Herman and Yeremian, Dian and /SLAC and Meyerhofer, David and Reis, David and /Rochester U.},
abstractNote = {A photocathode RF gun test stand is under construction in the injector vault of the Stanford Synchrotron Radiation Laboratory at SLAC. The goal of this facility is to produce an electron beam with a normalized emittance of 1-3[mm-mr], a longitudinal bunch duration of the order of 10[ps] FWHM and approximately 1[nC] of charge per bunch. The beam will be generated from a laser driven copper photocathode RF gun developed in collaboration with BNL, LBL and UCLA. The 3-5[MeV] beam from the gun will be accelerated using a SLAC three meter S-band accelerator section. The emittance of the electron beam will be measured through the use of quadrupole scans with phosphor screens and also a wire scanner. The details of the experimental setup will be discussed, and first measurements will be presented and compared with results from PARMELA simulations.},
doi = {},
journal = {Conf.Proc.C970512:2840,1997},
number = ,
volume = ,
place = {United States},
year = {Thu Sep 01 00:00:00 EDT 2011},
month = {Thu Sep 01 00:00:00 EDT 2011}
}

Conference:
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  • The Linac Coherent Light Source (LCLS) at SLAC requires the rf photoinjector to produce a beam with a normalized, projected emittance of 1 micron in a 10 ps long bunch with a charge of 1nC. In addition, a small longitudinal emittance is needed to attain the desired 3 kiloamperes peak current after compression in two chicane bunchers. To achieve this excellent beam quality, we are performing systematic studies of both the transverse and longitudinal beam properties from the rf photocathode gun at the SLAC Gun Test Facility (GTF). Time resolved emittances (slice) are determined by using a bunch with amore » linear energy chirp which is dispersed by a magnetic spectrometer. By varying the strength of a quadrupole lens upstream of the spectrometer allows measurement of the individual slice emittances. Spectrometer images at the various quadrupole settings are binned in small energy/time windows and analyzed for the slice parameters. Our measurements indicate a temporal resolution of approximately 100 femtoseconds. In addition, the longitudinal phase space distribution is determined by measuring the energy spectrum over a range of linac phases. The correlated and uncorrelated components of the phase space distribution are determined by fits to the energy spectra analogous to a quad scan in the transverse dimension. The combined analysis of the transverse and longitudinal data gives not only the slice and longitudinal emittances, but also any correlations due to wakefields or other effects.« less
  • At the Gun Test Facility (GTF), we have been testing an S-band RF gun similar to the one to be used in the Linac Coherent Light Source (LCLS) Photo-Injector. The beam transverse properties have been extensively characterized on that gun and it was shown that this gun is capable of providing slice emittances of less than 1 mm.mrad for 100A slices [1]. The longitudinal beam properties are now also being investigated for 2 principal reasons: (1) the transverse beam properties are correlated to the longitudinal one; an excessively large correlated energy spread at the gun exit would damage the emittancemore » compensation; and (2) the uncorrelated rms energy spread as small as 10keV at the gun exit is required for a good lasing in the LCLS. To measure the longitudinal emittance, the booster phase scan technique has been used at the GTF as described in [2]. We have now performed simulations of this experiment to better understand the non-linear effects and to reconstitute the longitudinal emittance.« less
  • A photocathode RF gun test stand designed for the production and study of high brightness electron beams will be constructed at SSRL. The beam will be generated from a laser driven third generation photocathode RF gun being developed in collaboration with BNL, LBL, and UCLA. The 3-5 [MeV] beam from the gun will be accelerated using a SLAC three meter S-band accelerator section, in order to achieve the desired low emittance beam, emittance compensation with solenoidal focusing will be employed.
  • Damage threshold fluences for several optical components were measured at three wavelengths using the injector laser at SSRL's Gun Test Facility. Measurements were conducted using the fundamental ir wavelength at 1053 nanometers and harmonics at 526 nm and 263 nm with 3.4ps pulses (1/e{sup 2} full width intensity); ir measurements were also conducted with 850 ps pulses. Practical surfaces relevant to the laser system performance are emphasized. Damage onset was evidenced by an alteration of the specular reflection of a cw probe laser (650 nm) from the irradiated region of the target surface. For the case of stretched ir pulses,more » damage to a Nd:glass rod was observed to begin at a site within the bulk material and to progress back toward the incident surface.« less
  • We have built a high-DC-voltage photoemission gun and a diagnostic beamline permitting us to measure rms transverse emittance ({epsilon}{sub x}) and rms momentum spread ({delta}) of short-duration electron pulses produced by illuminating the cathode with light from a mode-locked, frequency-doubled Nd:YLF laser. The electron gun is a GaAs photocathode source designed to operate at 500kV. We have measured {epsilon}{sub x} and {delta} for conditions ranging from emittance-dominated to space-charge-dominated. We report these measurements as functions of microbunch charge for different beam radii, pulse lengths, and voltages/field gradients at the cathode, and compare them with PARMELA calculations.