ERL2019 - List of Authors (Lou, W.)

Paper	Title	Page
TUCOWBS03	CSR Phase Space Dilution in CBETA
	W. Lou, G.H. Hoffstaetter, D. Sagan Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA C.E. Mayes SLAC, Menlo Park, California, USA
	While Energy Recovery Linac (ERLs) give promise to deliver unprecedentedly high beam current with simultaneously small emittance, Coherent Synchrotron Radiation (CSR) can pose detrimental effect on the beam at high bunch charges and short bunch lengths. CBETA, the Cornell BNL ERL Test Accelerator, will be the first multi-turn ERL with SRF accelerating cavities and Fixed Field Alternating gradient (FFA) beamline. To investigate the CSR effects on CBETA, the established simulation code Bmad has been used to track a bunch with different CSR parameters. We found that CSR causes phase space dilution, and the effect becomes more significant as the bunch charge and recirculation pass increase. Convergence tests have been performed for the CSR parameters to validate the observed micro-bunching instability. Potential ways to mitigate the effect involving vacuum chamber shielding and increasing bunch length are also being investigated.
	Slides TUCOWBS03 [5.215 MB]
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TUCOXBS05	Beam Timing and Cavity Phasing	39
	R.M. Koscica, N. Banerjee, G.H. Hoffstaetter, W. Lou, G.T. Premawardhana Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
	In a multi-pass Energy Recovery Linac (ERL), each cavity must regain all energy expended from beam acceleration during beam deceleration. The beam should also achieve specific energy targets during each loop that returns it to the linac. To satisfy the energy recovery and loop requirements, one must specify the phase and voltage of cavity fields, and one must control the beam flight times through the return loops. Adequate values for these parameters can be found by using a full scale numerical optimization program. If symmetry is imposed in beam time and energy during acceleration and deceleration, the number of parameters needed decreases, simplifying the optimization. As an example, symmetric models of the Cornell BNL ERL Test Accelerator (CBETA) are considered. Energy recovery results from recent CBETA single-turn tests are presented, as well as multi-turn solutions that satisfy CBETA optimization targets of loop energy and zero cavity loading.
	Slides TUCOXBS05 [5.186 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-ERL2019-TUCOXBS05
About •	paper received ※ 13 September 2019 paper accepted ※ 01 November 2019 issue date ※ 24 June 2020
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

Paper

Title

Page

TUCOWBS03

CSR Phase Space Dilution in CBETA

W. Lou, G.H. Hoffstaetter, D. Sagan
Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
C.E. Mayes
SLAC, Menlo Park, California, USA

While Energy Recovery Linac (ERLs) give promise to deliver unprecedentedly high beam current with simultaneously small emittance, Coherent Synchrotron Radiation (CSR) can pose detrimental effect on the beam at high bunch charges and short bunch lengths. CBETA, the Cornell BNL ERL Test Accelerator, will be the first multi-turn ERL with SRF accelerating cavities and Fixed Field Alternating gradient (FFA) beamline. To investigate the CSR effects on CBETA, the established simulation code Bmad has been used to track a bunch with different CSR parameters. We found that CSR causes phase space dilution, and the effect becomes more significant as the bunch charge and recirculation pass increase. Convergence tests have been performed for the CSR parameters to validate the observed micro-bunching instability. Potential ways to mitigate the effect involving vacuum chamber shielding and increasing bunch length are also being investigated.

Slides TUCOWBS03 [5.215 MB]

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TUCOXBS05

Beam Timing and Cavity Phasing

39

R.M. Koscica, N. Banerjee, G.H. Hoffstaetter, W. Lou, G.T. Premawardhana
Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA

In a multi-pass Energy Recovery Linac (ERL), each cavity must regain all energy expended from beam acceleration during beam deceleration. The beam should also achieve specific energy targets during each loop that returns it to the linac. To satisfy the energy recovery and loop requirements, one must specify the phase and voltage of cavity fields, and one must control the beam flight times through the return loops. Adequate values for these parameters can be found by using a full scale numerical optimization program. If symmetry is imposed in beam time and energy during acceleration and deceleration, the number of parameters needed decreases, simplifying the optimization. As an example, symmetric models of the Cornell BNL ERL Test Accelerator (CBETA) are considered. Energy recovery results from recent CBETA single-turn tests are presented, as well as multi-turn solutions that satisfy CBETA optimization targets of loop energy and zero cavity loading.

Slides TUCOXBS05 [5.186 MB]

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-ERL2019-TUCOXBS05

About •

paper received ※ 13 September 2019 paper accepted ※ 01 November 2019 issue date ※ 24 June 2020

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)