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Title: RF Measurement and High-Power Test of a 1.6-cell Photocathode RF Gun at Pohang Accelerator Laboratory

Abstract

No abstract prepared.

Authors:
; ; ; ; ; ; ; ; ;
Publication Date:
Research Org.:
Brookhaven National Laboratory (BNL) National Synchrotron Light Source
Sponsoring Org.:
Doe - Office Of Science
OSTI Identifier:
929935
Report Number(s):
BNL-80529-2008-JA
Journal ID: ISSN 0374-4884; KPSJAS; TRN: US0806671
DOE Contract Number:
DE-AC02-98CH10886
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of the Korean Physical Society; Journal Volume: 50; Journal Issue: 5
Country of Publication:
United States
Language:
English
Subject:
43 PARTICLE ACCELERATORS; ACCELERATORS; ACCELERATOR FACILITIES; ELECTRON GUNS; PHOTOCATHODES; national synchrotron light source

Citation Formats

Park,J., Ko, I., Park, S., Park, Y., Kim, S., Huang, J., Parc, Y., Hong, J., Xiang, D., and Wang, X. RF Measurement and High-Power Test of a 1.6-cell Photocathode RF Gun at Pohang Accelerator Laboratory. United States: N. p., 2007. Web. doi:10.3938/jkps.50.1443.
Park,J., Ko, I., Park, S., Park, Y., Kim, S., Huang, J., Parc, Y., Hong, J., Xiang, D., & Wang, X. RF Measurement and High-Power Test of a 1.6-cell Photocathode RF Gun at Pohang Accelerator Laboratory. United States. doi:10.3938/jkps.50.1443.
Park,J., Ko, I., Park, S., Park, Y., Kim, S., Huang, J., Parc, Y., Hong, J., Xiang, D., and Wang, X. Mon . "RF Measurement and High-Power Test of a 1.6-cell Photocathode RF Gun at Pohang Accelerator Laboratory". United States. doi:10.3938/jkps.50.1443.
@article{osti_929935,
title = {RF Measurement and High-Power Test of a 1.6-cell Photocathode RF Gun at Pohang Accelerator Laboratory},
author = {Park,J. and Ko, I. and Park, S. and Park, Y. and Kim, S. and Huang, J. and Parc, Y. and Hong, J. and Xiang, D. and Wang, X.},
abstractNote = {No abstract prepared.},
doi = {10.3938/jkps.50.1443},
journal = {Journal of the Korean Physical Society},
number = 5,
volume = 50,
place = {United States},
year = {Mon Jan 01 00:00:00 EST 2007},
month = {Mon Jan 01 00:00:00 EST 2007}
}
  • We report the first operation of a 17 GHz RF photocathode electron gun. This is the first photocathode electron gun to operate at a frequency above 2.856 GHz. Such electron guns have the potential for achieving record high values of electron beam quality. The 1(1)/(2) cell, {pi}-mode, copper cavity was tested with 5{endash}10 MW, 100 ns, 17.145 GHz pulses from a 24 MW Haimson Research Corp. klystron amplifier. Klystron power is stable to within {plus_minus}5{percent} up to 15 MW. Conditioning resulted in a maximum surface field of 250 MV/m, corresponding to an on-axis gradient of 150 MV/m. Dark current ofmore » 0.5 mA was observed at 175 MV/m, consistent with Fowler-Nordheim field emission theory if a field enhancement factor of about 100 is assumed. Electron bunches were generated by a regenerative laser amplifier that produces 2 ps, 1.9 mJ pulses at 800 nm with {plus_minus}10{percent} energy stability. These pulses were frequency tripled to 46 {mu}J of UV, and then focused on the wall of the cavity. Preliminary beam measurements indicate 0.12 nC bunches were produced with a kinetic energy of about 1 MeV. This corresponds to a peak current of about 100 A, and a density at the cathode of 2kA/cm{sup 2}. Both single and multiple pulse laser induced beam emission were observed. {copyright} {ital 1997 American Institute of Physics.}« less
  • A dedicated low energy (2 to 10 MeV) experimental beam line is now under construction at Brookhaven National Laboratories Accelerator Test Facility (BNL/ATF) for photocathode RF gun testing and photoemission experiments. The design of the experimental line, using the 1.6 cell photocathode RF gun developed by the BNL/SLAC/UCLA RF gun collaboration is presented. Detailed beam dynamics simulations were performed for the 1.6 cell RF gun injector using a solenoidal emittance compensation technique. An experimental program for testing the 1.6 cell RF gun is presented. This program includes beam loading caused by dark current, higher order mode field measurements, integrated andmore » slice emittance measurements using a pepper-pot and RF kicker cavity.« less
  • The longitudinal accelerating field E. has been measured as a function of azimuthal angle in the full cell of the cold test model for the 1.6 cell BNL/SLAC/UCLA {number_sign}3 S-band RF Gun using a needle rotation/frequency perturbation technique. These measurements were conducted before and after symmetrizing the full cell with a vacuum pump out port and an adjustable short. Two different waveguide to full cell coupling schemes were studied. The dipole mode of the full cell is an order of magnitude less severe before symmetrization for the 0{theta}-coupling scheme. The multi-pole contribution to the longitudinal field asymmetry are calculated usingmore » standard Fourier series techniques. The Panofsky-Wenzel theorem is used in estimating the transverse emittance due to the multipole components of E{sub x}.« less
  • The symmetrized 1.6 cell S-band photocathode gun developed by the BNL/SLAC/UCLA collaboration is in operation at the Brookhaven Accelerator Test Facility (ATF). A novel emittance compensation solenoid magnet has also been designed, built and is in operation at the ATF. These two subsystems form an emittance compensated photoinjector used for beam dynamics, advanced acceleration and free electron laser experiments at the ATF. The highest acceleration field achieved on the copper cathode is 150 MV/m, and the guns normal operating field is 130 MV/m. The maximum rf pulse length is 3 {micro}s. The transverse emittance of the photoelectron beam were measuredmore » for various injection parameters. The 1 nC emittance results are presented along with electron bunch length measurements that indicated that at above the 400 pC, space charge bunch lengthening is occurring. The thermal emittance, {epsilon}{sub o}, of the copper cathode has been measured.« less