IPAC2018 - List of Authors (Leemans, W.)

Paper	Title	Page
TUPML042	Accurate Modeling of the Hose Instability in Plasma Based Accelerators	1638
	T.J. Mehrling, C. Benedetti, E. Esarey, W. Leemans, C.B. Schroeder LBNL, Berkeley, California, USA
	Funding: US Department of Energy Contract No. DE-AC02-05CH11231 The hose instability is a long standing challenge for plasma-based accelerators. It is seeded by initial transverse asymmetries of the beam or plasma phase space distributions. The beam centroid displacement is thereby amplified during the propagation in the plasma, which can lead to an unstable acceleration process. A witness beam can itself cause hosing and/or may be affected by the hosing of the drive beam. The accurate study of hosing including a witness beam is of utmost importance to facilitate stable plasma-based accelerators. In this contribution, we discuss novel methods for the mitigation of hosing and present a new model for the evolution of the plasma centroid, which enables the accurate investigation of the hose instability of drive and witness beam pair in the nonlinear blowout regime. This work enables more precise and comprehensive studies of hosing and hence, for the potential stabilization of future compact plasma-based accelerators.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUPML042
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WEPAL041	FPGA Based Optical Phase Control for Coherent Laser Pulse Stacking	2265
	Y. Yang, L.R. Doolittle, Q. Du, G. Huang, W. Leemans, R.B. Wilcox, T. Zhou LBNL, Berkeley, California, USA A. Galvanauskas University of Michigan, Ann Arbor, Michigan, USA
	Coherent temporal pulse stacking combines the energy from a train of pulses into one pulse through a series of optical cavities. To stabilize the output energy, the cavity roundtrip phases must be precisely locked to particular values. Leveraging the LLRF expertise we have for conventional accelerators, a FPGA-based control system has been developed for optical cavity phase control. A phase measurement method, ''Modulated Impulse Response'', has been developed and implemented on FPGA. An experiment demonstrated that it can measure and lock the optical phases of four stacking cavities, leading to combination of 25 pulses into one pulse with 1.5 % RMS stability over 30 hours.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPAL041
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THPML002	Emittance Preservation in Plasma-Based Accelerators with Ion Motion	4654
	C. Benedetti, E. Esarey, W. Leemans, T.J. Mehrling, C.B. Schroeder LBNL, Berkeley, California, USA
	Funding: This work was supported by the Director, Office of Science, Office of High Energy Physics, of the U.S. DOE under Contract No. DE-AC02-05CH11231. In a plasma-accelerator-based linear collider, the density of matched, low-emittance, high-energy particle bunches required for collider applications can be orders of magnitude above the background ion density, leading to ion motion, perturbation of the focusing fields, and, hence, to beam emittance growth. By analyzing the response of the background ions to an ultrahigh density beam, analytical expressions, valid for non-relativistic ion motion, are obtained for the perturbed focusing wakefield. Initial beam distributions are derived that are equilibrium solutions, which require head-to-tail bunch shaping, enabling emittance preservation with ion motion.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPML002
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THPML099	Phase Extraction and Stabilization for Coherent Pulse Stacking	4895
SUSPL060	use link to see paper's listing under its alternate paper code
	Y.L. Xu, W.-H. Huang, C.-X. Tang, L.X. Yan TUB, Beijing, People's Republic of China L.R. Doolittle, Q. Du, G. Huang, W. Leemans, D. Li, R.B. Wilcox, Y. Yang, T. Zhou LBNL, Berkeley, California, USA A. Galvanauskas University of Michigan, Ann Arbor, Michigan, USA
	Funding: This work was supported by the U.S. Department of Energy, Office of Science, Office of High Energy Physics, under Contract DE-AC02-05CH11231. Coherent pulse stacking (CPS) is a new time-domain coherent addition technique that stacks several optical pulses into a single output pulse, enabling high pulse energy and high average power. We model the CPS as a digital filter in the Z domain, and implement two deterministic algorithms extracting the cavity phase from limited data where only the pulse intensity is available. In a 2-stage 15-pulse CPS system, each optical cavity is stabilized at an individually-prescribed round-trip phase with 0.7 deg and 2.1 deg RMS phase errors for Stage 1 and Stage 2 respectively. Optical cavity phase control with nm accuracy ensures 1.2% intensity stability of the stacked pulse over 12 hours.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPML099
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Paper

Title

Page

Accurate Modeling of the Hose Instability in Plasma Based Accelerators

1638

T.J. Mehrling, C. Benedetti, E. Esarey, W. Leemans, C.B. Schroeder
LBNL, Berkeley, California, USA

Funding: US Department of Energy Contract No. DE-AC02-05CH11231
The hose instability is a long standing challenge for plasma-based accelerators. It is seeded by initial transverse asymmetries of the beam or plasma phase space distributions. The beam centroid displacement is thereby amplified during the propagation in the plasma, which can lead to an unstable acceleration process. A witness beam can itself cause hosing and/or may be affected by the hosing of the drive beam. The accurate study of hosing including a witness beam is of utmost importance to facilitate stable plasma-based accelerators. In this contribution, we discuss novel methods for the mitigation of hosing and present a new model for the evolution of the plasma centroid, which enables the accurate investigation of the hose instability of drive and witness beam pair in the nonlinear blowout regime. This work enables more precise and comprehensive studies of hosing and hence, for the potential stabilization of future compact plasma-based accelerators.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUPML042

Export •

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

WEPAL041

FPGA Based Optical Phase Control for Coherent Laser Pulse Stacking

2265

Y. Yang, L.R. Doolittle, Q. Du, G. Huang, W. Leemans, R.B. Wilcox, T. Zhou
LBNL, Berkeley, California, USA
A. Galvanauskas
University of Michigan, Ann Arbor, Michigan, USA

Coherent temporal pulse stacking combines the energy from a train of pulses into one pulse through a series of optical cavities. To stabilize the output energy, the cavity roundtrip phases must be precisely locked to particular values. Leveraging the LLRF expertise we have for conventional accelerators, a FPGA-based control system has been developed for optical cavity phase control. A phase measurement method, ''Modulated Impulse Response'', has been developed and implemented on FPGA. An experiment demonstrated that it can measure and lock the optical phases of four stacking cavities, leading to combination of 25 pulses into one pulse with 1.5 % RMS stability over 30 hours.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPAL041

Export •

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

THPML002

Emittance Preservation in Plasma-Based Accelerators with Ion Motion

4654

C. Benedetti, E. Esarey, W. Leemans, T.J. Mehrling, C.B. Schroeder
LBNL, Berkeley, California, USA

Funding: This work was supported by the Director, Office of Science, Office of High Energy Physics, of the U.S. DOE under Contract No. DE-AC02-05CH11231.
In a plasma-accelerator-based linear collider, the density of matched, low-emittance, high-energy particle bunches required for collider applications can be orders of magnitude above the background ion density, leading to ion motion, perturbation of the focusing fields, and, hence, to beam emittance growth. By analyzing the response of the background ions to an ultrahigh density beam, analytical expressions, valid for non-relativistic ion motion, are obtained for the perturbed focusing wakefield. Initial beam distributions are derived that are equilibrium solutions, which require head-to-tail bunch shaping, enabling emittance preservation with ion motion.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPML002

Export •

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

THPML099

Phase Extraction and Stabilization for Coherent Pulse Stacking

4895

SUSPL060

use link to see paper's listing under its alternate paper code

Y.L. Xu, W.-H. Huang, C.-X. Tang, L.X. Yan
TUB, Beijing, People's Republic of China
L.R. Doolittle, Q. Du, G. Huang, W. Leemans, D. Li, R.B. Wilcox, Y. Yang, T. Zhou
LBNL, Berkeley, California, USA
A. Galvanauskas
University of Michigan, Ann Arbor, Michigan, USA

Funding: This work was supported by the U.S. Department of Energy, Office of Science, Office of High Energy Physics, under Contract DE-AC02-05CH11231.
Coherent pulse stacking (CPS) is a new time-domain coherent addition technique that stacks several optical pulses into a single output pulse, enabling high pulse energy and high average power. We model the CPS as a digital filter in the Z domain, and implement two deterministic algorithms extracting the cavity phase from limited data where only the pulse intensity is available. In a 2-stage 15-pulse CPS system, each optical cavity is stabilized at an individually-prescribed round-trip phase with 0.7 deg and 2.1 deg RMS phase errors for Stage 1 and Stage 2 respectively. Optical cavity phase control with nm accuracy ensures 1.2% intensity stability of the stacked pulse over 12 hours.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPML099

Export •

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