NAPAC2016 - List of Authors (Doolittle, L.R.)

Paper	Title	Page
MOA2IO01	Towards Attosecond Synchronization in Ultrafast Light Sources
	R.B. Wilcox, J.M. Byrd, L.R. Doolittle, G. Huang LBNL, Berkeley, California, USA
	This presentation will report on the latest results of the SNS fast feedback system commissioning and Beam Transfer Function experimental study
	Slides MOA2IO01 [2.842 MB]
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TUPOA14	An Internet Rack Monitor-Controller for APS LINAC RF Electronics Upgrade	314
	H. Ma, A. Nassiri, T.L. Smith, Y. Sun ANL, Argonne, Illinois, USA L.R. Doolittle, A. Ratti LBNL, Berkeley, California, USA
	Funding: Work supported by U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences To support the current research and development in APS LINAC area, the existing LINAC rf control performance needs to be much improved, and thus an upgrade of the legacy LINAC rf electronics becomes necessary. The proposed upgrade plan centers on the concept of using a modern, network-attached, rack-mount digital electronics platform 'Internet Rack Monitor-Controller (or IRMC) to replace the existing analog ones on the legacy crate/backplane-based hardware. The system model of the envisioned IRMC is basically a 3-tier stack with a high-performance processor in the mid- layer to handle the general digital signal processing (DSP). The custom FPGA IP's in the bottom layer handle the high-speed, real-time, low-latency DSP tasks, and provide the interface ports. A network communication gateway, in conjunction with an embedded event receiver (EVR), in the top layer merges the Internet Rack Monitor-Controller device into the networks of the accelerator controls infrastructure. Although the concept is very much in trend with today's Internet-of-Things (IoT), this implementation has actually been used in accelerators for over two decades.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2016-TUPOA14
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TUPOA40	Low Noise Digitizer Design for LCLS-II LLRF	364
	G. Huang, L.R. Doolittle, Y.L. Xu, J. Yang LBNL, Berkeley, California, USA Y.L. Xu, J. Yang TUB, Beijing, People's Republic of China
	Modern accelerators use a digital low level RF controller to stabilize the fields in accelerator cavities. The noise in the receiver chain and analog to digital conversion (ADC) for the cavity probe signal is critically important. Within the closed-loop bandwidth, it will eventually become part of the field noise seen by the beam in the accelerator. Above the open-loop cavity bandwidth, feedback processes transfer that noise to the high power drive amplifiers. The LCLS-II project is expected to use an undulator to provide soft X-rays based on a stable electron beam accelerated by a superconducting linac. Project success depends on a low noise, low crosstalk analog to digital conversion. We developed a digitizer board with 8 ADC channels and 2 DAC channels. The broadband phase noise of this board is measured at <-151\thinspace dBc/Hz, and the adjacent channel crosstalk is measured at <-80\thinspace dB. In this paper we describe the digitizer board design, performance test procedures, and bench-test results.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2016-TUPOA40
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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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FRA2IO02	High Precision RF Control for the LCLS-II	1292
	G. Huang, K. Campbell, L.R. Doolittle, J.A. Jones, C. Serrano, V.K. Vytla LBNL, Berkeley, California, USA S. Babel, M. Boyes, G.W. Brown, D. Cha, B. Hong, A. Ratti, C.H. Rivetta SLAC, Menlo Park, California, USA R. Bachimanchi, C. Hovater, D.J. Seidman JLab, Newport News, Virginia, USA B.E. Chase, E. Cullerton, Q. Du, J. Einstein, D.W. Klepec Fermilab, Batavia, Illinois, USA
	Funding: Work supported by the LCLS-II Project and the U.S. Department of Energy, Contract DE-AC02-76SF00515 The LCLS-II is a CW superconducting linac under construction to drive an X-ray FEL. The energy and timing stability requirements of the FEL drive the need for very high precision RF control. This paper summarize the design considerations and early demonstration of the performance of the components and system we developed.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2016-FRA2IO02
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

Paper

Title

Page

MOA2IO01

Towards Attosecond Synchronization in Ultrafast Light Sources

R.B. Wilcox, J.M. Byrd, L.R. Doolittle, G. Huang
LBNL, Berkeley, California, USA

This presentation will report on the latest results of the SNS fast feedback system commissioning and Beam Transfer Function experimental study

Slides MOA2IO01 [2.842 MB]

Export •

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

TUPOA14

An Internet Rack Monitor-Controller for APS LINAC RF Electronics Upgrade

314

H. Ma, A. Nassiri, T.L. Smith, Y. Sun
ANL, Argonne, Illinois, USA
L.R. Doolittle, A. Ratti
LBNL, Berkeley, California, USA

Funding: Work supported by U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences
To support the current research and development in APS LINAC area, the existing LINAC rf control performance needs to be much improved, and thus an upgrade of the legacy LINAC rf electronics becomes necessary. The proposed upgrade plan centers on the concept of using a modern, network-attached, rack-mount digital electronics platform 'Internet Rack Monitor-Controller (or IRMC) to replace the existing analog ones on the legacy crate/backplane-based hardware. The system model of the envisioned IRMC is basically a 3-tier stack with a high-performance processor in the mid- layer to handle the general digital signal processing (DSP). The custom FPGA IP's in the bottom layer handle the high-speed, real-time, low-latency DSP tasks, and provide the interface ports. A network communication gateway, in conjunction with an embedded event receiver (EVR), in the top layer merges the Internet Rack Monitor-Controller device into the networks of the accelerator controls infrastructure. Although the concept is very much in trend with today's Internet-of-Things (IoT), this implementation has actually been used in accelerators for over two decades.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2016-TUPOA14

Export •

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

TUPOA40

Low Noise Digitizer Design for LCLS-II LLRF

364

G. Huang, L.R. Doolittle, Y.L. Xu, J. Yang
LBNL, Berkeley, California, USA
Y.L. Xu, J. Yang
TUB, Beijing, People's Republic of China

Modern accelerators use a digital low level RF controller to stabilize the fields in accelerator cavities. The noise in the receiver chain and analog to digital conversion (ADC) for the cavity probe signal is critically important. Within the closed-loop bandwidth, it will eventually become part of the field noise seen by the beam in the accelerator. Above the open-loop cavity bandwidth, feedback processes transfer that noise to the high power drive amplifiers. The LCLS-II project is expected to use an undulator to provide soft X-rays based on a stable electron beam accelerated by a superconducting linac. Project success depends on a low noise, low crosstalk analog to digital conversion. We developed a digitizer board with 8 ADC channels and 2 DAC channels. The broadband phase noise of this board is measured at <-151\thinspace dBc/Hz, and the adjacent channel crosstalk is measured at <-80\thinspace dB. In this paper we describe the digitizer board design, performance test procedures, and bench-test results.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2016-TUPOA40

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)

FRA2IO02

High Precision RF Control for the LCLS-II

1292

G. Huang, K. Campbell, L.R. Doolittle, J.A. Jones, C. Serrano, V.K. Vytla
LBNL, Berkeley, California, USA
S. Babel, M. Boyes, G.W. Brown, D. Cha, B. Hong, A. Ratti, C.H. Rivetta
SLAC, Menlo Park, California, USA
R. Bachimanchi, C. Hovater, D.J. Seidman
JLab, Newport News, Virginia, USA
B.E. Chase, E. Cullerton, Q. Du, J. Einstein, D.W. Klepec
Fermilab, Batavia, Illinois, USA

Funding: Work supported by the LCLS-II Project and the U.S. Department of Energy, Contract DE-AC02-76SF00515
The LCLS-II is a CW superconducting linac under construction to drive an X-ray FEL. The energy and timing stability requirements of the FEL drive the need for very high precision RF control. This paper summarize the design considerations and early demonstration of the performance of the components and system we developed.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2016-FRA2IO02

Export •

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