NAPAC2016 - List of Authors (Yang, Y.)

Paper	Title	Page
MOPOB47	Beam Coupling Impedance Characterization of Third Harmonic Cavity for ALS Upgrade	167
	T.H. Luo, K.M. Baptiste, M. Betz, J.M. Byrd, S. De Santis, S. Kwiatkowski, S. Persichelli, Y. Yang LBNL, Berkeley, California, USA
	The ALS upgrade to a diffraction-limited light source (ALS-U) depends on the ability to lengthen the stored bunches to limit the emittance growth and increase the beam life time. In order to achieve lengthening in excess of fourfold necessary to this end, we are investigating the use of the same passive 1.5 GHz normal-conducting RF cavities currently used on the ALS. While the upgraded ring RF parameters and fill pattern make it easier as long as the beam-induced phase transient is concerned, the large lengthening factor and the strongly non-linear lattice require particular attention to the cavities contribution to the machine overall impedance budget. In this paper we present our estimates of the narrow-band impedance obtained by numerical simulation and bench measurements of the cavities' resonant modes.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2016-MOPOB47
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TUPOA41	FPGA Control of Coherent Pulse Stacking	367
SUPO52	use link to see paper's listing under its alternate paper code
	Y.L. Xu, J.M. Byrd, L.R. Doolittle, Q. Du, G. Huang, W. Leemans, R.B. Wilcox, Y. Yang LBNL, Berkeley, California, USA J. Dawson LLNL, Livermore, California, USA A. Galvanauskas, J.M. Ruppe University of Michigan, Ann Arbor, Michigan, USA
	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 from fiber lasers. Due to advantages of precise timing and fast processing, we use an FPGA to process digital signals and do feedback control so as to realize stacking-cavity stabilization. We develop a hardware and firmware design platform to support the coherent pulse stacking application. A firmware bias control module stabilizes the amplitude modulator at the minimum of its transfer function. A cavity control module ensures that each optical cavity is kept at a certain individually-prescribed and stable round-trip phase with 2.5 deg rms phase error.
	Poster TUPOA41 [5.546 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2016-TUPOA41
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TUPOA42	Multicavity Coherent Pulse Stacking Using Herriott Cells	370
	Y. Yang, J.M. Byrd, L.R. Doolittle, G. Huang, W. Leemans, Q. Qiang, R.B. Wilcox LBNL, Berkeley, California, USA J. Dawson LLNL, Livermore, California, USA A. Galvanauskas, J.M. Ruppe University of Michigan, Ann Arbor, Michigan, USA Y.L. Xu TUB, Beijing, People's Republic of China
	Coherent Pulse Stacking provides a promising way to generate a single high-intensity laser pulse by stacking a sequence of phase and amplitude modulated laser pulses using multiple optical cavities. Optical misalignment and phase stability are two critical issues that need to be addressed. Herriott cells are implemented for their relaxed alignment tolerance and a phase stabilization method based on cavity output pattern matching has been developed. A single pulse with intensity enhancement factor over 7.4 has been generated by stacking 13 modulated pules through a four-cavity stacking system. This can be a possible path for generating TW KHz laser pulses for a future laser-driven plasma accelerator.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2016-TUPOA42
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THPOA33	A Preliminary Beam Impedance Model of the Advanced Light Source Upgrade at LBL	1174
	S. Persichelli, J.M. Byrd, S. De Santis, D. Li, T.H. Luo, J.R. Osborn, C.A. Swenson, M. Venturini, Y. Yang LBNL, Berkeley, California, USA
	The proposed upgrade of the Advanced Light Source (ALS-U) consists of a multi-bend achromat ultralow emittance lattice optimized for the production of diffraction-limited soft x-rays. A narrow-aperture vacuum chamber is a key feature of the new generation of light sources, and can result in a significant increase in the beam impedance, potentially limiting the maximum achievable beam current. While the conceptual design of the vacuum system is still in a very early development stage, this paper presents a preliminary estimate of the beam impedance using a combination of electromagnetic simulations and analytical calculations. We include the impedance of cavities, select vacuum-chamber components and resistive wall in a multi-layered beam chamber with NEG coating.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2016-THPOA33
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Paper

Title

Page

Beam Coupling Impedance Characterization of Third Harmonic Cavity for ALS Upgrade

167

T.H. Luo, K.M. Baptiste, M. Betz, J.M. Byrd, S. De Santis, S. Kwiatkowski, S. Persichelli, Y. Yang
LBNL, Berkeley, California, USA

The ALS upgrade to a diffraction-limited light source (ALS-U) depends on the ability to lengthen the stored bunches to limit the emittance growth and increase the beam life time. In order to achieve lengthening in excess of fourfold necessary to this end, we are investigating the use of the same passive 1.5 GHz normal-conducting RF cavities currently used on the ALS. While the upgraded ring RF parameters and fill pattern make it easier as long as the beam-induced phase transient is concerned, the large lengthening factor and the strongly non-linear lattice require particular attention to the cavities contribution to the machine overall impedance budget. In this paper we present our estimates of the narrow-band impedance obtained by numerical simulation and bench measurements of the cavities' resonant modes.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2016-MOPOB47

Export •

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

TUPOA41

FPGA Control of Coherent Pulse Stacking

367

SUPO52

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

Y.L. Xu, J.M. Byrd, L.R. Doolittle, Q. Du, G. Huang, W. Leemans, R.B. Wilcox, Y. Yang
LBNL, Berkeley, California, USA
J. Dawson
LLNL, Livermore, California, USA
A. Galvanauskas, J.M. Ruppe
University of Michigan, Ann Arbor, Michigan, USA

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 from fiber lasers. Due to advantages of precise timing and fast processing, we use an FPGA to process digital signals and do feedback control so as to realize stacking-cavity stabilization. We develop a hardware and firmware design platform to support the coherent pulse stacking application. A firmware bias control module stabilizes the amplitude modulator at the minimum of its transfer function. A cavity control module ensures that each optical cavity is kept at a certain individually-prescribed and stable round-trip phase with 2.5 deg rms phase error.

Poster TUPOA41 [5.546 MB]

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2016-TUPOA41

Export •

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

TUPOA42

Multicavity Coherent Pulse Stacking Using Herriott Cells

370

Y. Yang, J.M. Byrd, L.R. Doolittle, G. Huang, W. Leemans, Q. Qiang, R.B. Wilcox
LBNL, Berkeley, California, USA
J. Dawson
LLNL, Livermore, California, USA
A. Galvanauskas, J.M. Ruppe
University of Michigan, Ann Arbor, Michigan, USA
Y.L. Xu
TUB, Beijing, People's Republic of China

Coherent Pulse Stacking provides a promising way to generate a single high-intensity laser pulse by stacking a sequence of phase and amplitude modulated laser pulses using multiple optical cavities. Optical misalignment and phase stability are two critical issues that need to be addressed. Herriott cells are implemented for their relaxed alignment tolerance and a phase stabilization method based on cavity output pattern matching has been developed. A single pulse with intensity enhancement factor over 7.4 has been generated by stacking 13 modulated pules through a four-cavity stacking system. This can be a possible path for generating TW KHz laser pulses for a future laser-driven plasma accelerator.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2016-TUPOA42

Export •

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

THPOA33

A Preliminary Beam Impedance Model of the Advanced Light Source Upgrade at LBL

1174

S. Persichelli, J.M. Byrd, S. De Santis, D. Li, T.H. Luo, J.R. Osborn, C.A. Swenson, M. Venturini, Y. Yang
LBNL, Berkeley, California, USA

The proposed upgrade of the Advanced Light Source (ALS-U) consists of a multi-bend achromat ultralow emittance lattice optimized for the production of diffraction-limited soft x-rays. A narrow-aperture vacuum chamber is a key feature of the new generation of light sources, and can result in a significant increase in the beam impedance, potentially limiting the maximum achievable beam current. While the conceptual design of the vacuum system is still in a very early development stage, this paper presents a preliminary estimate of the beam impedance using a combination of electromagnetic simulations and analytical calculations. We include the impedance of cavities, select vacuum-chamber components and resistive wall in a multi-layered beam chamber with NEG coating.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2016-THPOA33

Export •

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