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Title: Ultra-High Gradient Dielectric Wakefield Accelerator Experiments

Abstract

Ultra-high gradient dielectric wakefield accelerators are a potential option for a linear collider afterburner since they are immune to the ion collapse and electron/positron asymmetry problems implicit in a plasma based afterburner. The first phase of an experiment to study the performance of dielectric Cerenkov wakefield accelerating structures at extremely high gradients in the GV/m range has been completed. The experiment took advantage of the unique SLAC FFTB electron beam and its ultra-short pulse lengths and high currents (e.g., {sigma}{sub z} = 20 {micro}m at Q = 3 nC). The FFTB electron beam was successfully focused down and sent through short lengths of fused silica capillary tubing (ID = 200 {micro}m/OD = 325 {micro}m). The pulse length of the electron beam was varied to produce a range of electric fields between 2 and 20 GV/m at the inner surface of the dielectric tubes. We observed a sharp increase in optical emissions from the capillaries in the middle part of this surface field range which we believe indicates the transition between sustainable field levels and breakdown. If this initial interpretation is correct, the surfaced fields that were sustained equate to on axis accelerating field of several GV/m. In future experiments beingmore » developed for the SLAC SABER and BNL ATF we plan to use the coherent Cerenkov radiation emitted from the capillary tube as a field strength diagnostic and demonstrate GV/m range particle energy gain.« less

Authors:
; ; ; ; ; ; ; ; ; ; ; ;
Publication Date:
Research Org.:
Stanford Linear Accelerator Center (SLAC)
Sponsoring Org.:
USDOE
OSTI Identifier:
901585
Report Number(s):
SLAC-PUB-12420
TRN: US0702599
DOE Contract Number:
AC02-76SF00515
Resource Type:
Conference
Resource Relation:
Journal Name: AIP Conf.Proc.877:903-909,2006; Conference: Prepared for 12th Advanced Accelerator Concepts Workshop (AAC 2006), Lake Geneva, Wisconsin, 10-15 Jul 2006
Country of Publication:
United States
Language:
English
Subject:
43 PARTICLE ACCELERATORS; 36 MATERIALS SCIENCE; ACCELERATORS; AFTERBURNERS; ASYMMETRY; BREAKDOWN; CAPILLARIES; DIELECTRIC MATERIALS; ELECTRIC FIELDS; ELECTRON BEAMS; LINEAR COLLIDERS; PERFORMANCE; RADIATIONS; SILICA; STANFORD LINEAR ACCELERATOR CENTER; WAKEFIELD ACCELERATORS; Accelerators,ACCPHY

Citation Formats

Thompson, M.C., Badakov, H., Rosenzweig, J.B., Travish, G., Hogan, M., Ischebeck, R., Kirby, N., Siemann, R., Walz, D., Muggli, P., Scott, A., Yoder, R., and /LLNL, Livermore /UCLA /SLAC /Southern California U. /UC, Santa Barbara /Manhattan Coll., Riverdale. Ultra-High Gradient Dielectric Wakefield Accelerator Experiments. United States: N. p., 2007. Web.
Thompson, M.C., Badakov, H., Rosenzweig, J.B., Travish, G., Hogan, M., Ischebeck, R., Kirby, N., Siemann, R., Walz, D., Muggli, P., Scott, A., Yoder, R., & /LLNL, Livermore /UCLA /SLAC /Southern California U. /UC, Santa Barbara /Manhattan Coll., Riverdale. Ultra-High Gradient Dielectric Wakefield Accelerator Experiments. United States.
Thompson, M.C., Badakov, H., Rosenzweig, J.B., Travish, G., Hogan, M., Ischebeck, R., Kirby, N., Siemann, R., Walz, D., Muggli, P., Scott, A., Yoder, R., and /LLNL, Livermore /UCLA /SLAC /Southern California U. /UC, Santa Barbara /Manhattan Coll., Riverdale. Tue . "Ultra-High Gradient Dielectric Wakefield Accelerator Experiments". United States. doi:. https://www.osti.gov/servlets/purl/901585.
@article{osti_901585,
title = {Ultra-High Gradient Dielectric Wakefield Accelerator Experiments},
author = {Thompson, M.C. and Badakov, H. and Rosenzweig, J.B. and Travish, G. and Hogan, M. and Ischebeck, R. and Kirby, N. and Siemann, R. and Walz, D. and Muggli, P. and Scott, A. and Yoder, R. and /LLNL, Livermore /UCLA /SLAC /Southern California U. /UC, Santa Barbara /Manhattan Coll., Riverdale},
abstractNote = {Ultra-high gradient dielectric wakefield accelerators are a potential option for a linear collider afterburner since they are immune to the ion collapse and electron/positron asymmetry problems implicit in a plasma based afterburner. The first phase of an experiment to study the performance of dielectric Cerenkov wakefield accelerating structures at extremely high gradients in the GV/m range has been completed. The experiment took advantage of the unique SLAC FFTB electron beam and its ultra-short pulse lengths and high currents (e.g., {sigma}{sub z} = 20 {micro}m at Q = 3 nC). The FFTB electron beam was successfully focused down and sent through short lengths of fused silica capillary tubing (ID = 200 {micro}m/OD = 325 {micro}m). The pulse length of the electron beam was varied to produce a range of electric fields between 2 and 20 GV/m at the inner surface of the dielectric tubes. We observed a sharp increase in optical emissions from the capillaries in the middle part of this surface field range which we believe indicates the transition between sustainable field levels and breakdown. If this initial interpretation is correct, the surfaced fields that were sustained equate to on axis accelerating field of several GV/m. In future experiments being developed for the SLAC SABER and BNL ATF we plan to use the coherent Cerenkov radiation emitted from the capillary tube as a field strength diagnostic and demonstrate GV/m range particle energy gain.},
doi = {},
journal = {AIP Conf.Proc.877:903-909,2006},
number = ,
volume = ,
place = {United States},
year = {Tue Mar 27 00:00:00 EDT 2007},
month = {Tue Mar 27 00:00:00 EDT 2007}
}

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  • Ultra-high gradient dielectric wakefield accelerators are a potential option for a linear collider afterburner since they are immune to the ion collapse and electron/positron asymmetry problems implicit in a plasma based afterburner. The first phase of an experiment to study the performance of dielectric Cerenkov wakefield accelerating structures at extremely high gradients in the GV/m range has been completed. The experiment took advantage of the unique SLAC FFTB electron beam and its ultra-short pulse lengths and high currents (e.g., {sigma}{sub z} = 20 {micro}m at Q = 3 nC). The FFTB electron beam was successfully focused down and sent throughmore » short lengths of fused silica capillary tubing (ID = 200 {micro}m/OD = 325 {micro}m). The pulse length of the electron beam was varied to produce a range of electric fields between 2 and 20 GV/m at the inner surface of the dielectric tubes. We observed a sharp increase in optical emissions from the capillaries in the middle part of this surface field range which we believe indicates the transition between sustainable field levels and breakdown. If this initial interpretation is correct, the surfaced fields that were sustained equate to on axis accelerating field of several GV/m. In future experiments being developed for the SLAC SABER and BNL ATF we plan to use the coherent Cerenkov radiation emitted from the capillary tube as a field strength diagnostic and demonstrate GV/m range particle energy gain.« less
  • Ultra-high gradient dielectric wakefield accelerators are a potential option for a linear collider afterburner since they are immune to the ion collapse and electron/positron asymmetry problems implicit in a plasma based afterburner. The first phase of an experiment to study the performance of dielectric Cerenkov wakefield accelerating structures at extremely high gradients in the GV/m range has been completed. The experiment took advantage of the unique SLAC FFTB electron beam and its ultra-short pulse lengths and high currents (e.g., {sigma}z = 20 {mu}m at Q = 3 nC). The FFTB electron beam was successfully focused down and sent through shortmore » lengths of fused silica capillary tubing (ID = 200 {mu}m / OD = 325 {mu}m). The pulse length of the electron beam was varied to produce a range of electric fields between 2 and 20 GV/m at the inner surface of the dielectric tubes. We observed a sharp increase in optical emissions from the capillaries in the middle part of this surface field range which we believe indicates the transition between sustainable field levels and breakdown. If this initial interpretation is correct, the surfaced fields that were sustained equate to on axis accelerating field of several GV/m. In future experiments being developed for the SLAC SABER and BNL ATF we plan to use the coherent Cerenkov radiation emitted from the capillary tube as a field strength diagnostic and demonstrate GV/m range particle energy gain.« less
  • In beam driven dielectric wakefield acceleration (DWA), high-gradient short-wavelength accelerating fields are generally achieved by employing dielectric-lined waveguides (DLWs)  with small aperture which constraints the beam sizes. In this paper we investigate the possibility of using a low-energy (50-MeV) flat beams to induce high-gradient wakes in a slab-symmetric DLW. We demonstrate via numerical simulations the possibility to produce axial electric field with peak amplitude close to 0.5 GV/m. Our studies are carried out using the Fermilab's Advanced Superconducting Test Accelerator (ASTA) photoinjector beamline. We finally discuss a possible experiment that could be performed in the ASTA photoinjector and eventually atmore » higher energies.  « less
  • The Argonne Wakefield Accelerator (AWA) is a facility designed to investigate high gradient wakefield acceleration techniques. Wakefields are excited using a drive beam produced by a 14 MeV high current photoinjector-based linac. A second photocathode gun generates a 4 MeV witness beam which is used as a probe of the wakefields in the device under test. The delay of the witness bunch with respect to the drive bunch can be continuously varied from -100 ps to >1 ns. The drive and witness bunches propagate along collinear or parallel trajectories through the test section. A dipole spectrometer is then used tomore » measure the energy change of the witness beam. The complete wakefield measurement system has been commissioned and wakefield experiments using dielectric structures are underway. Initial experiments have focused on collinear wakefield device geometries where the drive and witness bunches traverse the same structure. For attaining very high gradients we will construct and study step-up transformer structures in which the rf pulse generated by the drive beam is compressed transversely and longitudinally.« less
  • An experiment is planned to study the performance of dielectric Cerenkov wakefield accelerating structures at extremely high gradients in the GV/m range. This new UCLA/SLAC/USC collaboration will take advantage of the unique SLAC FFTB electron beam and its demonstrated ultra-short pulse lengths and high currents (e.g., {delta}{sub z} = 20 {micro}m at Q = 3 nC). The electron beam will be focused down and sent through varying lengths of fused silica capillary tubing with two different sizes: ID = 200 {micro}m/OD = 325 {micro}m and ID = 100 {micro}m/OD = 325 {micro}m. The pulse length of the electron beam willmore » be varied in order to alter the accelerating gradient and probe the breakdown threshold of the dielectric structures. In addition to breakdown studies, we plan to collect and measure coherent Cerenkov radiation emitted from the capillary tube to gain information about the strength of the accelerating fields.« less