IPAC2015 - List of Authors (England, R.J.)

Paper	Title	Page
WEPWA053	First Acceleration in a Resonant Optical-Scale Laser-Powered Structure	2624
	R.B. Yoder Goucher College, Baltimore, Maryland, USA R.J. England, Z. Wu SLAC, Menlo Park, California, USA K.S. Hazra, B. Matthews, J.C. McNeur, E.B. Sozer, G. Travish UCLA, Los Angeles, California, USA E.A. Peralta, K. Soong Stanford University, Stanford, California, USA
	Funding: U.S. DTRA grant HDTRA1-09-1-0043 The Micro-Accelerator Platform (MAP), an optical-scale dielectric laser accelerator (DLA) based on a planar resonant structure that was developed at UCLA, has been tested experimentally. Successful acceleration was observed after a series of experimental runs at SLAC’s NLCTA facility, in which the input laser power was well below the predicted breakdown limit. Though acceleration gradients were modest (<50 MeV/m), these are the first proof-of-principle results for a resonant DLA structure. We present more detailed results and some implications for future work.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-WEPWA053
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WEPJE012	Design and Optimisation of Dielectric Laser Deflecting Structures	2698
	K.P. Wootton, R.J. England, I.V. Makasyuk, Z. Wu SLAC, Menlo Park, California, USA R.L. Byer, E.A. Peralta Stanford University, Stanford, California, USA A.D. Tafel Friedrich-Alexander Universität Erlangen-Nuernberg, University Erlangen-Nuernberg LFTE, Erlangen, Germany
	Funding: This work was supported by the U.S. Department of Energy under Grants DE-AC02-76SF00515, and DE-FG02-13ER41970. Recent experimental demonstrations of dielectric laser-driven accelerator structures offer a path to the miniaturisation of accelerators. In order to accelerate particles to higher energies using a staged sequence of accelerating structures, integrating compatible micrometre-scale transverse deflecting structures into these accelerators is necessary. Using simulations, the present work outlines the design and optimisation of a fused-silica laser-driven grating deflecting structure for relativistic electron beams. Implications for device fabrication and experiments are outlined.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-WEPJE012
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WEPJE013	A New Accelerating Mode in a Silicon Woodpile Structure and Its High-efficiency Power Coupler Design	2702
	Z. Wu, R.J. England, C. Lee, C.-K. Ng, K.P. Wootton SLAC, Menlo Park, California, USA
	Funding: Work supported by U.S. Department of Energy under Grants DE-AC02-76SF00515, DE-FG02-13ER41970 and by DARPA Grant N66001-11-1-4199. Silicon woodpile photonic crystals provide a base structure that can be used to build a three-dimensional dielectric waveguide system for high-gradient laser-driven acceleration. A new woodpile waveguide design that hosts a phase synchronous, centrally confined accelerating mode with ideal Gaussian transverse profile is proposed. Comparing with previously discovered silicon woodpile accelerating modes, this mode shows advantages in better beam loading and higher achievable acceleration gradient. Several travelling-wave coupler design schemes developed for multi-cell RF cavity accelerators are adapted to the woodpile accelerator coupler design based on this new accelerating mode. A forward-wave-coupled, highly efficient silicon woodpile accelerator is achieved. Simulation shows high efficiency of over 70% of the drive laser power coupled to this fundamental woodpile accelerating mode, with less than 15% backward wave excitation. The estimated acceleration gradient, when the coupler structure is driven at the damage threshold fluence of silicon at its operating 1.506 um wavelength, can reach roughly 185 MV/m.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-WEPJE013
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WEPJE021	Fabrication and Demonstration of a Silicon Buried Grating Accelerator	2717
	A.C. Ceballos, R.L. Byer, K.J. Leedle, E.A. Peralta, O. Solgaard, K. Soong Stanford University, Stanford, California, USA R.J. England, I.V. Makasyuk, K.P. Wootton, Z. Wu SLAC, Menlo Park, California, USA A. Hanuka Technion, Haifa, Israel A.D. Tafel Friedrich-Alexander Universität Erlangen-Nuernberg, University Erlangen-Nuernberg LFTE, Erlangen, Germany
	Funding: Work supported by the U.S. Department of Energy under Grants DE-AC02-76SF00515, DE-FG06-97ER41276. Using optical electromagnetic fields in dielectric microstructures, we can realize higher-energy accelerator systems in a more compact, low-cost form than the current state-of-the-art. Dielectric, laser-driven accelerators (DLA) have recently been demonstrated using fused silica structures to achieve about an order-of-magnitude increase in accelerating gradient over conventional RF structures.* We leverage higher damage thresholds of silicon over metals and extensive micromachining capability to fabricate structures capable of electron acceleration. Our monolithic structure, the buried grating, consists of a grating formed on either side of a long channel via a deep reactive ion etch (DRIE).** The grating imposes a phase profile on an incoming laser pulse such that an electron experiences a net change in energy over the course of each optical cycle. This results in acceleration (or deceleration) as electrons travel down the channel. We have designed and fabricated such structures and begun testing at the SLAC National Accelerator Laboratory. We report on the progress toward demonstration of acceleration in these structures driven at 2um wavelength. * E.A. Peralta et al., Nature 503 (2013) ** C.M. Chang and O. Solgaard, Appl. Phys. Lett. 104 (2014)
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-WEPJE021
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Paper

Title

Page

First Acceleration in a Resonant Optical-Scale Laser-Powered Structure

2624

R.B. Yoder
Goucher College, Baltimore, Maryland, USA
R.J. England, Z. Wu
SLAC, Menlo Park, California, USA
K.S. Hazra, B. Matthews, J.C. McNeur, E.B. Sozer, G. Travish
UCLA, Los Angeles, California, USA
E.A. Peralta, K. Soong
Stanford University, Stanford, California, USA

Funding: U.S. DTRA grant HDTRA1-09-1-0043
The Micro-Accelerator Platform (MAP), an optical-scale dielectric laser accelerator (DLA) based on a planar resonant structure that was developed at UCLA, has been tested experimentally. Successful acceleration was observed after a series of experimental runs at SLAC’s NLCTA facility, in which the input laser power was well below the predicted breakdown limit. Though acceleration gradients were modest (<50 MeV/m), these are the first proof-of-principle results for a resonant DLA structure. We present more detailed results and some implications for future work.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-WEPWA053

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WEPJE012

Design and Optimisation of Dielectric Laser Deflecting Structures

2698

K.P. Wootton, R.J. England, I.V. Makasyuk, Z. Wu
SLAC, Menlo Park, California, USA
R.L. Byer, E.A. Peralta
Stanford University, Stanford, California, USA
A.D. Tafel
Friedrich-Alexander Universität Erlangen-Nuernberg, University Erlangen-Nuernberg LFTE, Erlangen, Germany

Funding: This work was supported by the U.S. Department of Energy under Grants DE-AC02-76SF00515, and DE-FG02-13ER41970.
Recent experimental demonstrations of dielectric laser-driven accelerator structures offer a path to the miniaturisation of accelerators. In order to accelerate particles to higher energies using a staged sequence of accelerating structures, integrating compatible micrometre-scale transverse deflecting structures into these accelerators is necessary. Using simulations, the present work outlines the design and optimisation of a fused-silica laser-driven grating deflecting structure for relativistic electron beams. Implications for device fabrication and experiments are outlined.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-WEPJE012

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

WEPJE013

A New Accelerating Mode in a Silicon Woodpile Structure and Its High-efficiency Power Coupler Design

2702

Z. Wu, R.J. England, C. Lee, C.-K. Ng, K.P. Wootton
SLAC, Menlo Park, California, USA

Funding: Work supported by U.S. Department of Energy under Grants DE-AC02-76SF00515, DE-FG02-13ER41970 and by DARPA Grant N66001-11-1-4199.
Silicon woodpile photonic crystals provide a base structure that can be used to build a three-dimensional dielectric waveguide system for high-gradient laser-driven acceleration. A new woodpile waveguide design that hosts a phase synchronous, centrally confined accelerating mode with ideal Gaussian transverse profile is proposed. Comparing with previously discovered silicon woodpile accelerating modes, this mode shows advantages in better beam loading and higher achievable acceleration gradient. Several travelling-wave coupler design schemes developed for multi-cell RF cavity accelerators are adapted to the woodpile accelerator coupler design based on this new accelerating mode. A forward-wave-coupled, highly efficient silicon woodpile accelerator is achieved. Simulation shows high efficiency of over 70% of the drive laser power coupled to this fundamental woodpile accelerating mode, with less than 15% backward wave excitation. The estimated acceleration gradient, when the coupler structure is driven at the damage threshold fluence of silicon at its operating 1.506 um wavelength, can reach roughly 185 MV/m.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-WEPJE013

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WEPJE021

Fabrication and Demonstration of a Silicon Buried Grating Accelerator

2717

A.C. Ceballos, R.L. Byer, K.J. Leedle, E.A. Peralta, O. Solgaard, K. Soong
Stanford University, Stanford, California, USA
R.J. England, I.V. Makasyuk, K.P. Wootton, Z. Wu
SLAC, Menlo Park, California, USA
A. Hanuka
Technion, Haifa, Israel
A.D. Tafel
Friedrich-Alexander Universität Erlangen-Nuernberg, University Erlangen-Nuernberg LFTE, Erlangen, Germany

Funding: Work supported by the U.S. Department of Energy under Grants DE-AC02-76SF00515, DE-FG06-97ER41276.
Using optical electromagnetic fields in dielectric microstructures, we can realize higher-energy accelerator systems in a more compact, low-cost form than the current state-of-the-art. Dielectric, laser-driven accelerators (DLA) have recently been demonstrated using fused silica structures to achieve about an order-of-magnitude increase in accelerating gradient over conventional RF structures.* We leverage higher damage thresholds of silicon over metals and extensive micromachining capability to fabricate structures capable of electron acceleration. Our monolithic structure, the buried grating, consists of a grating formed on either side of a long channel via a deep reactive ion etch (DRIE).** The grating imposes a phase profile on an incoming laser pulse such that an electron experiences a net change in energy over the course of each optical cycle. This results in acceleration (or deceleration) as electrons travel down the channel. We have designed and fabricated such structures and begun testing at the SLAC National Accelerator Laboratory. We report on the progress toward demonstration of acceleration in these structures driven at 2um wavelength.
* E.A. Peralta et al., Nature 503 (2013)
** C.M. Chang and O. Solgaard, Appl. Phys. Lett. 104 (2014)

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-WEPJE021

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