2011 Particle Accelerator Conference - List of Authors (Sutter, D.F.)

Paper

Title

Page

Space-Charge Effects in Bunched and Debunched Beams

85

B.L. Beaudoin, S. Bernal, K. Fiuza, I. Haber, R.A. Kishek, T.W. Koeth, P.G. O'Shea, M. Reiser, D.F. Sutter
UMD, College Park, Maryland, USA

Funding: This work is funded by the US Dept. of Energy Offices of High Energy Physics and High Energy Density Physics, and by the US Dept. of Defense Office of Naval Research and Joint Technology Office
The University of Maryland Electron Ring (UMER) is a machine designed to study high-intensity beam physics. With the application of axial fields to the bunch ends, we are able to keep a beam with an injected tune shift of 1.0, bunched over multiple turns. This is feasible with the application of tailored fields to optimally match the space-charge self-fields while minimizing the excitation of longitudinal space-charge waves. With this scheme, we have been able to extend the number of turns at the University of Maryland Electron Ring (UMER) by a factor of ten. Without the use of longitudinal focusing, head and tail effects begin to dominate, especially with the higher current beams. Time resolved measurements of the peak correlated energy spread have shown in some cases a change in the overall spread of 1.8% for the 0.6 mA beam, from the injected beam energy.

Slides MOODS1 [2.834 MB]

WEP050

Advances in Modeling the University of Maryland Electron Ring

1585

R.A. Kishek, B.L. Beaudoin, S. Bernal, M. Cornacchia, K. Fiuza, I. Haber, T.W. Koeth, P.G. O'Shea, D.F. Sutter, H.D. Zhang
UMD, College Park, Maryland, USA

Funding: Work funded by the US Dept. of Energy Offices of Fusion Energy Sciences and High Energy Physics, and by the Dept. of Defense Office of Naval Research and the Joint Technology Office.
The University of Maryland Electron Ring (UMER) is a research accelerator designed to operate with extreme space charge. The existence of high-precision experimental measurements of tune, dispersion, chromaticity, response matrix elements, and other parameters*, **, *** has prompted a revision of the models used to describe the machine. Due to the low energy (10 keV) of the electrons, the dipole and quadrupole magnets used are air-core printed-circuit coils whose fields we calculate using a Biot-Savart solver. Different levels of approximations for the magnetic fields have been developed. We present simulation results from the particle-in-cell code WARP, and from the accelerator code, ELEGANT. These are compared both against simpler models as well as experimental results. The improved modeling has significantly reduced the discrepancies between simulation and experiment.
* D.F. Sutter, et al., Proc. PAC 2009
** C. Wu, et al., Proc. PAC 2009
*** S. Bernal, et al., Proc. AAC 2010

WEP102

Current Dependent Tune Shifts in the University of Maryland Electron Ring UMER

1668

D.F. Sutter, B.L. Beaudoin, S. Bernal, M. Cornacchia, R.A. Kishek, T.W. Koeth, P.G. O'Shea
UMD, College Park, Maryland, USA

Funding: Work supported by the U.S. DOE Offices of High Energy Physics and Fusion Energy Sciences and by the U.S. DOD Office of Naval Research and Joint Technology Office.
The shift in betatron tunes as a function of space charge has been studied in many accelerators and storage rings. Because of its low operating energy (10 keV, γ = 1.02) and wide range of beam currents (0.6 to 100 mA, corresponding respectively to predicted incoherent tune shifts of 1.2 to 5.2), the University of Maryland electron ring (UMER) provides a unique opportunity to study space charge driven tune shifts over a wide parameter space. Comparisons of predictions and measurements are presented, including a discussion of special factors such as the magnetic penetration of the vacuum chamber walls.

Paper	Title	Page
MOODS1	Space-Charge Effects in Bunched and Debunched Beams	85
	B.L. Beaudoin, S. Bernal, K. Fiuza, I. Haber, R.A. Kishek, T.W. Koeth, P.G. O'Shea, M. Reiser, D.F. Sutter UMD, College Park, Maryland, USA
	Funding: This work is funded by the US Dept. of Energy Offices of High Energy Physics and High Energy Density Physics, and by the US Dept. of Defense Office of Naval Research and Joint Technology Office The University of Maryland Electron Ring (UMER) is a machine designed to study high-intensity beam physics. With the application of axial fields to the bunch ends, we are able to keep a beam with an injected tune shift of 1.0, bunched over multiple turns. This is feasible with the application of tailored fields to optimally match the space-charge self-fields while minimizing the excitation of longitudinal space-charge waves. With this scheme, we have been able to extend the number of turns at the University of Maryland Electron Ring (UMER) by a factor of ten. Without the use of longitudinal focusing, head and tail effects begin to dominate, especially with the higher current beams. Time resolved measurements of the peak correlated energy spread have shown in some cases a change in the overall spread of 1.8% for the 0.6 mA beam, from the injected beam energy.
	Slides MOODS1 [2.834 MB]

WEP050	Advances in Modeling the University of Maryland Electron Ring	1585
	R.A. Kishek, B.L. Beaudoin, S. Bernal, M. Cornacchia, K. Fiuza, I. Haber, T.W. Koeth, P.G. O'Shea, D.F. Sutter, H.D. Zhang UMD, College Park, Maryland, USA
	Funding: Work funded by the US Dept. of Energy Offices of Fusion Energy Sciences and High Energy Physics, and by the Dept. of Defense Office of Naval Research and the Joint Technology Office. The University of Maryland Electron Ring (UMER) is a research accelerator designed to operate with extreme space charge. The existence of high-precision experimental measurements of tune, dispersion, chromaticity, response matrix elements, and other parameters, , ** has prompted a revision of the models used to describe the machine. Due to the low energy (10 keV) of the electrons, the dipole and quadrupole magnets used are air-core printed-circuit coils whose fields we calculate using a Biot-Savart solver. Different levels of approximations for the magnetic fields have been developed. We present simulation results from the particle-in-cell code WARP, and from the accelerator code, ELEGANT. These are compared both against simpler models as well as experimental results. The improved modeling has significantly reduced the discrepancies between simulation and experiment. * D.F. Sutter, et al., Proc. PAC 2009 C. Wu, et al., Proc. PAC 2009 * S. Bernal, et al., Proc. AAC 2010

WEP102	Current Dependent Tune Shifts in the University of Maryland Electron Ring UMER	1668
	D.F. Sutter, B.L. Beaudoin, S. Bernal, M. Cornacchia, R.A. Kishek, T.W. Koeth, P.G. O'Shea UMD, College Park, Maryland, USA
	Funding: Work supported by the U.S. DOE Offices of High Energy Physics and Fusion Energy Sciences and by the U.S. DOD Office of Naval Research and Joint Technology Office. The shift in betatron tunes as a function of space charge has been studied in many accelerators and storage rings. Because of its low operating energy (10 keV, γ = 1.02) and wide range of beam currents (0.6 to 100 mA, corresponding respectively to predicted incoherent tune shifts of 1.2 to 5.2), the University of Maryland electron ring (UMER) provides a unique opportunity to study space charge driven tune shifts over a wide parameter space. Comparisons of predictions and measurements are presented, including a discussion of special factors such as the magnetic penetration of the vacuum chamber walls.