Beam Breakup Effects in Dielectric Based Accelerators
Abstract
The dynamics of the beam in structurebased wakefield accelerators leads to beam stability issues not ordinarily found in other machines. In particular, the high current drive beam in an efficient wakefield accelerator loses a large fraction of its energy in the decelerator structure, resulting in physical emittance growth, increased energy spread, and the possibility of headtail instability for an off axis beam, all of which can lead to severe reduction of beam intensity. Beam breakup (BBU) effects resulting from parasitic wakefields provide a potentially serious limitation to the performance of dielectric structure based wakefield accelerators as well. We report on experimental and numerical investigation of BBU and its mitigation. The experimental program focuses on BBU measurements at the AWA facility in a number of high gradient and high transformer ratio wakefield devices. New pickupbased beam diagnostics will provide methods for studying parasitic wakefields that are currently unavailable. The numerical part of this research is based on a particleGreen's function beam breakup code we are developing that allows rapid, efficient simulation of beam breakup effects in advanced linear accelerators. The goal of this work is to be able to compare the results of detailed experimental measurements with the accurate numerical resultsmore »
 Authors:
 Euclid Techlabs LLC, Solon, OH 44139 (United States)
 (United States)
 Dynamics Software, Helsinki (Finland)
 Electrotechnical University Eltech 'LETI', St. Petersburg (Russian Federation)
 Argonne National Laboratory, IL (United States)
 Publication Date:
 OSTI Identifier:
 21255255
 Resource Type:
 Journal Article
 Resource Relation:
 Journal Name: AIP Conference Proceedings; Journal Volume: 1086; Journal Issue: 1; Conference: 13. advanced accelerator concepts workshop, Santa Cruz, CA (United States), 27 Jul  2 Aug 2008; Other Information: DOI: 10.1063/1.3080941; (c) 2009 American Institute of Physics; Country of input: International Atomic Energy Agency (IAEA)
 Country of Publication:
 United States
 Language:
 English
 Subject:
 71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSICS; DIELECTRIC MATERIALS; GREEN FUNCTION; INSTABILITY; MITIGATION; PERFORMANCE; SIMULATION; SPACE CHARGE; STABILITY; TRANSFORMERS; WAKEFIELD ACCELERATORS
Citation Formats
Schoessow, P., Kanareykin, A., Jing, C., Argonne National Laboratory, IL, Kustov, A., Altmark, A., Power, J. G., and Gai, W. Beam Breakup Effects in Dielectric Based Accelerators. United States: N. p., 2009.
Web. doi:10.1063/1.3080941.
Schoessow, P., Kanareykin, A., Jing, C., Argonne National Laboratory, IL, Kustov, A., Altmark, A., Power, J. G., & Gai, W. Beam Breakup Effects in Dielectric Based Accelerators. United States. doi:10.1063/1.3080941.
Schoessow, P., Kanareykin, A., Jing, C., Argonne National Laboratory, IL, Kustov, A., Altmark, A., Power, J. G., and Gai, W. 2009.
"Beam Breakup Effects in Dielectric Based Accelerators". United States.
doi:10.1063/1.3080941.
@article{osti_21255255,
title = {Beam Breakup Effects in Dielectric Based Accelerators},
author = {Schoessow, P. and Kanareykin, A. and Jing, C. and Argonne National Laboratory, IL and Kustov, A. and Altmark, A. and Power, J. G. and Gai, W.},
abstractNote = {The dynamics of the beam in structurebased wakefield accelerators leads to beam stability issues not ordinarily found in other machines. In particular, the high current drive beam in an efficient wakefield accelerator loses a large fraction of its energy in the decelerator structure, resulting in physical emittance growth, increased energy spread, and the possibility of headtail instability for an off axis beam, all of which can lead to severe reduction of beam intensity. Beam breakup (BBU) effects resulting from parasitic wakefields provide a potentially serious limitation to the performance of dielectric structure based wakefield accelerators as well. We report on experimental and numerical investigation of BBU and its mitigation. The experimental program focuses on BBU measurements at the AWA facility in a number of high gradient and high transformer ratio wakefield devices. New pickupbased beam diagnostics will provide methods for studying parasitic wakefields that are currently unavailable. The numerical part of this research is based on a particleGreen's function beam breakup code we are developing that allows rapid, efficient simulation of beam breakup effects in advanced linear accelerators. The goal of this work is to be able to compare the results of detailed experimental measurements with the accurate numerical results and to design an external FODO channel for the control of the beam in the presence of strong transverse wakefields.},
doi = {10.1063/1.3080941},
journal = {AIP Conference Proceedings},
number = 1,
volume = 1086,
place = {United States},
year = 2009,
month = 1
}

Structure mode frequency spreads are shown to have a rather different influence on beam breakup growths than betatron frequency spreads. The present analytic and numerical studies show that a finite spread in the breakup mode frequency leads to an algebraic decay of the beam breakup instabilities even if the quality factor /ital Q//r arrow/infinity. Effects of stagger tuning are examined.

Cumulative beam breakup in linear accelerators with periodic beam current
An analytic formalism of cumulative beam breakup in linear accelerators is developed. This formalism is applied to both lowvelocity ion accelerators and highenergy electron accelerators. It includes arbitrary velocity, acceleration, focusing, initial conditions, beamcavity resonances, finite bunch length, and arbitrary charge distribution within the bunches, and variable cavity geometry and spacing along the accelerator. For both directcurrent beams and beams comprised of {delta}function bunches, both the steadystate and transient displacements of the beam are calculated, and scaling laws are determined for the transient beam breakup. The steadystate transverse displacement of particles between bunches is also calculated since, if allowed tomore » 
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