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Title: The Bevalac long flattop

Abstract

Until July of 1992, the maximum length of the Bevalac flattop was 2 seconds, limiting the beam spill to 1.5 seconds. The normal running condition was a 1.5 second flattop, with a 1.0 second beam spill. If we define the duty factor as the spill length (in time) divided by the synchrotron pulse length, that is, the percentage of time the Bevalac can deliver beam to experiments, the duty factor for the 1.5 second flattop ranged from 17% (at full field, i.e., 12575 G) to 25% (low field). The purpose of the Long Flattop Project was to increase the length of the flattop, thus increasing the duty factor of the machine, and its efficiency for experiments. This has been done, with resultant increase in the duty factor and experimental data rate. It is now possible to run with duty factor of about 80% for low fields, falling to about 60% at 10 kG, and 34% at full field. This report documents what was done, and its limitations. It should be noted that increasing the length of the beam spill is only possible if the source can produce more beam per pulse than is usable by the experimenter. Experimenters running atmore » full intensity with a short flattop (1.5 seconds) cannot benefit from a longer flattop. This paper describe the changes that have been made to Bevalac systems to make the long flattop possible, the limits put on the length of the flattop by existing hardware, and the procedure for tuning for the long flattop.« less

Authors:
; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ;
Publication Date:
Research Org.:
Lawrence Berkeley Lab., CA (United States)
Sponsoring Org.:
USDOE, Washington, DC (United States)
OSTI Identifier:
10160374
Report Number(s):
LBL-33089
ON: DE93015223
DOE Contract Number:
AC03-76SF00098
Resource Type:
Technical Report
Resource Relation:
Other Information: PBD: Oct 1992
Country of Publication:
United States
Language:
English
Subject:
43 PARTICLE ACCELERATORS; BEVALAC; BEAM EXTRACTION; OPERATION; DIAGNOSTIC TECHNIQUES; MAGNETIC FIELDS; CONTROL SYSTEMS; FEEDBACK; MODIFICATIONS; 430100; 430302; DESIGN, DEVELOPMENT, AND OPERATION; INJECTION AND EXTRACTION SYSTEMS

Citation Formats

Celata, C.M., Abbott, S., Bennett, M., Bordua, M., Calvert, J., Dwinell, R., Howard, D., Hunt, D., Feinberg, B., Force, R., Frias, R., Kalnins, J., Lewis, S., Nyman, M., Shalz, L., Solomons, S.R., and Tekawa, M.. The Bevalac long flattop. United States: N. p., 1992. Web. doi:10.2172/10160374.
Celata, C.M., Abbott, S., Bennett, M., Bordua, M., Calvert, J., Dwinell, R., Howard, D., Hunt, D., Feinberg, B., Force, R., Frias, R., Kalnins, J., Lewis, S., Nyman, M., Shalz, L., Solomons, S.R., & Tekawa, M.. The Bevalac long flattop. United States. doi:10.2172/10160374.
Celata, C.M., Abbott, S., Bennett, M., Bordua, M., Calvert, J., Dwinell, R., Howard, D., Hunt, D., Feinberg, B., Force, R., Frias, R., Kalnins, J., Lewis, S., Nyman, M., Shalz, L., Solomons, S.R., and Tekawa, M.. Thu . "The Bevalac long flattop". United States. doi:10.2172/10160374. https://www.osti.gov/servlets/purl/10160374.
@article{osti_10160374,
title = {The Bevalac long flattop},
author = {Celata, C.M. and Abbott, S. and Bennett, M. and Bordua, M. and Calvert, J. and Dwinell, R. and Howard, D. and Hunt, D. and Feinberg, B. and Force, R. and Frias, R. and Kalnins, J. and Lewis, S. and Nyman, M. and Shalz, L. and Solomons, S.R. and Tekawa, M.},
abstractNote = {Until July of 1992, the maximum length of the Bevalac flattop was 2 seconds, limiting the beam spill to 1.5 seconds. The normal running condition was a 1.5 second flattop, with a 1.0 second beam spill. If we define the duty factor as the spill length (in time) divided by the synchrotron pulse length, that is, the percentage of time the Bevalac can deliver beam to experiments, the duty factor for the 1.5 second flattop ranged from 17% (at full field, i.e., 12575 G) to 25% (low field). The purpose of the Long Flattop Project was to increase the length of the flattop, thus increasing the duty factor of the machine, and its efficiency for experiments. This has been done, with resultant increase in the duty factor and experimental data rate. It is now possible to run with duty factor of about 80% for low fields, falling to about 60% at 10 kG, and 34% at full field. This report documents what was done, and its limitations. It should be noted that increasing the length of the beam spill is only possible if the source can produce more beam per pulse than is usable by the experimenter. Experimenters running at full intensity with a short flattop (1.5 seconds) cannot benefit from a longer flattop. This paper describe the changes that have been made to Bevalac systems to make the long flattop possible, the limits put on the length of the flattop by existing hardware, and the procedure for tuning for the long flattop.},
doi = {10.2172/10160374},
journal = {},
number = ,
volume = ,
place = {United States},
year = {Thu Oct 01 00:00:00 EDT 1992},
month = {Thu Oct 01 00:00:00 EDT 1992}
}

Technical Report:

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  • Until July of 1992, the maximum length of the Bevalac flattop was 2 seconds, limiting the beam spill to 1.5 seconds. The normal running condition was a 1.5 second flattop, with a 1.0 second beam spill. If we define the duty factor as the spill length (in time) divided by the synchrotron pulse length, that is, the percentage of time the Bevalac can deliver beam to experiments, the duty factor for the 1.5 second flattop ranged from 17% (at full field, i.e., 12575 G) to 25% (low field). The purpose of the Long Flattop Project was to increase the lengthmore » of the flattop, thus increasing the duty factor of the machine, and its efficiency for experiments. This has been done, with resultant increase in the duty factor and experimental data rate. It is now possible to run with duty factor of about 80% for low fields, falling to about 60% at 10 kG, and 34% at full field. This report documents what was done, and its limitations. It should be noted that increasing the length of the beam spill is only possible if the source can produce more beam per pulse than is usable by the experimenter. Experimenters running at full intensity with a short flattop (1.5 seconds) cannot benefit from a longer flattop. This paper describe the changes that have been made to Bevalac systems to make the long flattop possible, the limits put on the length of the flattop by existing hardware, and the procedure for tuning for the long flattop.« less
  • The temporal profile of the uv drive laser pulse for the LCLS injector is specified by the duration, the rise/fall time, and the maximum rms amplitude (for all frequencies) of residual modulation in the plateau region. The bandwidth of the uv laser system should accommodate pulses with a rise/fall time as low as 0.7 ps and an rms residual amplitude modulation (on the plateau) below 0.5% in the absence of a laser heater. Computations including the laser heater [3] relax this requirement to the 5% level. Numerical analyses of Fourier transform limited uv pulses show that the extent of frequencymore » sidebands should extend to at least 1.5 THz on either side of the central uv frequency. For simplicity, we assume that the emitted electron beam profile matches the laser profile. The evolution of those electron beam distributions in the longitudinal phase space along the beamline as calculated with PARMELA/ASTRA are shown. Related spectral and shaping requirements on the fundamental ir pulses are briefly addressed.« less