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

Paper

Title

Page

Status and Upgrades of the NLCTA for Studies of Advanced Beam Acceleration, Dynamics, and Manipulation

130

M.P. Dunning, C. Adolphsen, T.S. Chu, E.R. Colby, A. Gilevich, C. Hast, R.K. Jobe, C. Limborg-Deprey, D.J. McCormick, B.D. McKee, J. Nelson, T.O. Raubenheimer, K. Soong, G.V. Stupakov, Z.M. Szalata, D.R. Walz, F. Wang, S.P. Weathersby, M. Woodley, D. Xiang
SLAC, Menlo Park, California, USA

The Next Linear Collider Test Accelerator (NLCTA) is a low-energy electron accelerator (120 MeV) at SLAC that is used for ultra-high gradient X-band RF structure testing and advanced accelerator research. Here we give an overview of the current program at the facility, including the E-163 direct laser acceleration experiment, the echo-enabled harmonic generation (EEHG) FEL experiment, narrow-band THz generation, coherent optical transition radiation (COTR) studies, microbunching instability studies, and X-band structure testing. We also present the upgrades that are currently underway and some future programs utilizing these upgrades, including extension of the EEHG experiments to higher harmonics, and an emittance exchange experiment.

MOP015

An X-band Gun Test Area at SLAC

133

C. Limborg-Deprey, C. Adolphsen, T.S. Chu, M.P. Dunning, C. Hast, R.K. Jobe, E.N. Jongewaard, A.E. Vlieks, D.R. Walz, F. Wang
SLAC, Menlo Park, California, USA
S.G. Anderson, F.V. Hartemann, T.L. Houck, R.A. Marsh
LLNL, Livermore, California, USA

Funding: Work supported by the U.S. DOE Contract No. DE-AC03-76SF00515
The XTA (X-Band Test Area) is being assembled in the NLCTA tunnel of the SLAC National Laboratory to serve as a test facility for new RF guns. The first gun to be tested will be an upgraded version of the 5.6 cell, 200MV/m peak field X-band designed at SLAC in 2003 for the Compton Scattering experiment run in ASTA. This new version includes some features implemented in 2006 on the LCLS gun such as racetrack couplers, increased mode separation and elliptical irises. These upgrades were discussed in collaboration with LLNL since the same gun will be used as a driver for the LLNL Gamma-ray Source. Our beamline includes an X-band accelerating section which takes the electron beam up to 100 MeV and an electron beam measurement station. Other X-Band guns such as the UCLA Hybrid gun will be characterized at our facility.

MOP128

An Optimized X-band Photoinjector Design for the LLNL MEGa-Ray Project

334

S.G. Anderson, F. Albert, C.P.J. Barty, G.A. Deis, C.A. Ebbers, D.J. Gibson, F.V. Hartemann, T.L. Houck, R.A. Marsh
LLNL, Livermore, California, USA
C. Adolphsen, A.E. Candel, E.N. Jongewaard, Z. Li, C. Limborg-Deprey, T.O. Raubenheimer, S.G. Tantawi, A.E. Vlieks, F. Wang, J.W. Wang, F. Zhou
SLAC, Menlo Park, California, USA

Funding: This work performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344.
We present an optimized 5 + ½ cell, X-band photoinjector designed to produce 7 MeV, 250 pC, sub-micron emittance electron bunches for the LLNL Mono-Energetic Gamma-Ray (MEGa-Ray) light source. This LLNL/SLAC collaboration modifies a design previously demonstrated to sustain 200 MV/m on-axis accelerating fields*. We discuss the photoinjector operating point, optimized by scaling beam dynamics from S-band photo-guns and by evaluation of the MEGa-Ray source requirements. The RF structure design is presented along with the current status of the photoinjector construction and testing.
*A.E. Vlieks, et al., High Energy Density and High Power RF: 6th Workshop, AIP, CP691, p. 358 (2003).

TUP139

Initial High Power Test Results of an X-band Dual-moded Coaxial Cavity

1094

F. Wang, C. Adolphsen, C.D. Nantista
SLAC, Menlo Park, California, USA

To understand the rf breakdown phenomenon better, an x-band coaxial dual-moded cavity is designed. It is independently excited two modes from two sources. One mode will generator pulsed heating in the inner conductor and the other one will concentrate peak electric field. By observing the breakdown rate and damage on the surface for different electric to magnetic field ratios, we hope to reproduce the limiting RF field effects seen in various accelerator structure, waveguides and klystrons. The initial high power test has been done in SLAC. The experiment results will be discussed in the paper together with future experiments.

WEODS1

Design and Optimization of Future X-ray FELs based on Advanced High Frequency Linacs

1491

F. Wang
SLAC, Menlo Park, California, USA

To drive future XFELs, normal-conducting linacs at various rf freqencies are being considered. With optimized accelerator structures and rf systems, a higher rf frequency linac has several advantages, such as high acceleration gradient and high rf-to-beam efficiency. This paper presents a comparison of possible S-band, C-band and X-band linac designs for two cases, single bunch operation and multibunch operation, where the bunch train length is longer than the structure fill time and the beam loading is small. General scaling laws for the main linac parameters, which can be useful in the design such linacs, are derived.

Slides WEODS1 [5.795 MB]

THP146

Preliminary Study of Terahertz Free-Electron Laser Oscillator Based on Electrostatic Accelerator

2393

A.L. Wu, Q.K. Jia
USTC/NSRL, Hefei, Anhui, People's Republic of China
F. Wang, J. Wu
SLAC, Menlo Park, California, USA

Since the terahertz radiation sources provide wide applications in medical, industrial and material science, a compact, wavelength tunable and high-power THz source attracted much attention in many laboratories. In this paper, we give a primary study of a compact THz FEL based on electrostatic accelerator and the choice of basic design parameters is presented. The feasibility study is carried out using FELO codes. It is proved that FEL utilizing electrostatic accelerators (EA-FEL) will be a promising compact and powerful terahertz source.

TUP023

X-Band RF Photoinjector Research and Development at LLNL

859

R.A. Marsh, S.G. Anderson, C.P.J. Barty, G.K. Beer, R.R. Cross, G.A. Deis, C.A. Ebbers, D.J. Gibson, F.V. Hartemann, T.L. Houck
LLNL, Livermore, California, USA
C. Adolphsen, A.E. Candel, T.S. Chu, E.N. Jongewaard, Z. Li, C. Limborg-Deprey, T.O. Raubenheimer, S.G. Tantawi, A.E. Vlieks, F. Wang, J.W. Wang, F. Zhou
SLAC, Menlo Park, California, USA

Funding: This work performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344, and funded by DHS Domestic Nuclear Detection Office
In support of Compton scattering gamma-ray source efforts at LLNL, a multi-bunch test station is being developed to investigate accelerator optimization for future upgrades. This test station will enable work to explore the science and technology paths required to boost the current mono-energetic gamma-ray (MEGa-Ray) technology a higher effective repetition rate, potentially increasing the average gamma-ray brightness by two orders of magnitude. The test station will consist of a 5.5 cell X-band rf photoinjector, single accelerator section, and beam diagnostics. Beam quality must be exceedingly high in order to produce narrow-bandwidth gamma-rays, requiring a robust state of the art photoinjector. The photoinjector will be a high gradient (200 MV/m cathode field) standing wave structure, featuring a dual feed racetrack coupler, elliptical irises, and an optimized first cell length. Detailed design of the rf photoinjector for this test station is complete, and will be presented with modeling simulations, and layout plans.

TUP132

50 MW X-Band RF System for a Photoinjector Test Station at LLNL

1082

T.L. Houck, S.G. Anderson, C.P.J. Barty, G.K. Beer, R.R. Cross, G.A. Deis, C.A. Ebbers, D.J. Gibson, F.V. Hartemann, R.A. Marsh
LLNL, Livermore, California, USA
C. Adolphsen, A.E. Candel, T.S. Chu, E.N. Jongewaard, Z. Li, T.O. Raubenheimer, S.G. Tantawi, A.E. Vlieks, F. Wang, J.W. Wang, F. Zhou
SLAC, Menlo Park, California, USA

Funding: This work performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344, and funded by DHS Domestic Nuclear Detection Office.
In support of x-band photoinjector development efforts at LLNL, a 50 MW test station is being constructed to investigate structure and photocathode optimization for future upgrades. A SLAC XL-4 klystron capable of generating 50 MW, 1.5 microsecond pulses will be the high power RF source for the system. The timing of the laser pulse on the photocathode with the applied RF field places very stringent requirements on phase jitter and drift. To achieve these requirements, the klystron will be powered by a state of the art, solid-state, high voltage modulator. The 50 MW of RF power will be divided between the photoinjector and a traveling wave accelerator section. A high power phase shifter is located between the photoinjector and accelerator section to adjust the phasing of the electron bunches with respect to the accelerating field. A variable attenuator is included on the input of the photoinjector. The distribution system including the various x-band components is being designed and constructed. In this paper, we will present the design, layout, and status of the RF system.

THP182

Overview of Current Progress on the LLNL Nuclear Photonics Facility and Mono-energetic Gamma-ray Source

2456

F.V. Hartemann, F. Albert, S.G. Anderson, C.P.J. Barty, A.J. Bayramian, R.R. Cross, C.A. Ebbers, D.J. Gibson, T.L. Houck, R.A. Marsh, D.P. McNabb, M. J. Messerly, C. Siders
LLNL, Livermore, California, USA
C. Adolphsen, T.S. Chu, E.N. Jongewaard, T.O. Raubenheimer, S.G. Tantawi, A.E. Vlieks, F. Wang, J.W. Wang
SLAC, Menlo Park, California, USA

Funding: This work performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344
A new class of gamma-ray light source based on Compton scattering is made possible by recent progress in accelerator physics and laser technology. Mono-energetic gamma-rays are produced from collisions between a high-brightness, relativistic electron beam and a high intensity laser pulse produced via chirped-pulse amplification (CPA). A precision, tunable gamma-ray source driven by a compact, high-gradient X-band linac is currently under development and construction at LLNL. High-brightness, relativistic electron bunches produced by an X-band linear accelerator designed in collaboration with SLAC will interact with a Joule-class, 10 ps, diode-pumped CPA laser pulse to generate tunable gamma-rays in the 0.5-2.5 MeV photon energy range via Compton scattering. The source will be used to conduct nuclear resonance fluorescence experiments and address a broad range of current and emerging applications in nuclear photoscience. Users include homeland security, stockpile science and surveillance, nuclear fuel assay, and waste imaging and assay. The source design, key parameters, and current status are presented, along with important applications.

Paper	Title	Page
MOP014	Status and Upgrades of the NLCTA for Studies of Advanced Beam Acceleration, Dynamics, and Manipulation	130
	M.P. Dunning, C. Adolphsen, T.S. Chu, E.R. Colby, A. Gilevich, C. Hast, R.K. Jobe, C. Limborg-Deprey, D.J. McCormick, B.D. McKee, J. Nelson, T.O. Raubenheimer, K. Soong, G.V. Stupakov, Z.M. Szalata, D.R. Walz, F. Wang, S.P. Weathersby, M. Woodley, D. Xiang SLAC, Menlo Park, California, USA
	The Next Linear Collider Test Accelerator (NLCTA) is a low-energy electron accelerator (120 MeV) at SLAC that is used for ultra-high gradient X-band RF structure testing and advanced accelerator research. Here we give an overview of the current program at the facility, including the E-163 direct laser acceleration experiment, the echo-enabled harmonic generation (EEHG) FEL experiment, narrow-band THz generation, coherent optical transition radiation (COTR) studies, microbunching instability studies, and X-band structure testing. We also present the upgrades that are currently underway and some future programs utilizing these upgrades, including extension of the EEHG experiments to higher harmonics, and an emittance exchange experiment.

MOP015	An X-band Gun Test Area at SLAC	133
	C. Limborg-Deprey, C. Adolphsen, T.S. Chu, M.P. Dunning, C. Hast, R.K. Jobe, E.N. Jongewaard, A.E. Vlieks, D.R. Walz, F. Wang SLAC, Menlo Park, California, USA S.G. Anderson, F.V. Hartemann, T.L. Houck, R.A. Marsh LLNL, Livermore, California, USA
	Funding: Work supported by the U.S. DOE Contract No. DE-AC03-76SF00515 The XTA (X-Band Test Area) is being assembled in the NLCTA tunnel of the SLAC National Laboratory to serve as a test facility for new RF guns. The first gun to be tested will be an upgraded version of the 5.6 cell, 200MV/m peak field X-band designed at SLAC in 2003 for the Compton Scattering experiment run in ASTA. This new version includes some features implemented in 2006 on the LCLS gun such as racetrack couplers, increased mode separation and elliptical irises. These upgrades were discussed in collaboration with LLNL since the same gun will be used as a driver for the LLNL Gamma-ray Source. Our beamline includes an X-band accelerating section which takes the electron beam up to 100 MeV and an electron beam measurement station. Other X-Band guns such as the UCLA Hybrid gun will be characterized at our facility.

MOP128	An Optimized X-band Photoinjector Design for the LLNL MEGa-Ray Project	334
	S.G. Anderson, F. Albert, C.P.J. Barty, G.A. Deis, C.A. Ebbers, D.J. Gibson, F.V. Hartemann, T.L. Houck, R.A. Marsh LLNL, Livermore, California, USA C. Adolphsen, A.E. Candel, E.N. Jongewaard, Z. Li, C. Limborg-Deprey, T.O. Raubenheimer, S.G. Tantawi, A.E. Vlieks, F. Wang, J.W. Wang, F. Zhou SLAC, Menlo Park, California, USA
	Funding: This work performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344. We present an optimized 5 + ½ cell, X-band photoinjector designed to produce 7 MeV, 250 pC, sub-micron emittance electron bunches for the LLNL Mono-Energetic Gamma-Ray (MEGa-Ray) light source. This LLNL/SLAC collaboration modifies a design previously demonstrated to sustain 200 MV/m on-axis accelerating fields. We discuss the photoinjector operating point, optimized by scaling beam dynamics from S-band photo-guns and by evaluation of the MEGa-Ray source requirements. The RF structure design is presented along with the current status of the photoinjector construction and testing. A.E. Vlieks, et al., High Energy Density and High Power RF: 6th Workshop, AIP, CP691, p. 358 (2003).

TUP139	Initial High Power Test Results of an X-band Dual-moded Coaxial Cavity	1094
	F. Wang, C. Adolphsen, C.D. Nantista SLAC, Menlo Park, California, USA
	To understand the rf breakdown phenomenon better, an x-band coaxial dual-moded cavity is designed. It is independently excited two modes from two sources. One mode will generator pulsed heating in the inner conductor and the other one will concentrate peak electric field. By observing the breakdown rate and damage on the surface for different electric to magnetic field ratios, we hope to reproduce the limiting RF field effects seen in various accelerator structure, waveguides and klystrons. The initial high power test has been done in SLAC. The experiment results will be discussed in the paper together with future experiments.

WEODS1	Design and Optimization of Future X-ray FELs based on Advanced High Frequency Linacs	1491
	F. Wang SLAC, Menlo Park, California, USA
	To drive future XFELs, normal-conducting linacs at various rf freqencies are being considered. With optimized accelerator structures and rf systems, a higher rf frequency linac has several advantages, such as high acceleration gradient and high rf-to-beam efficiency. This paper presents a comparison of possible S-band, C-band and X-band linac designs for two cases, single bunch operation and multibunch operation, where the bunch train length is longer than the structure fill time and the beam loading is small. General scaling laws for the main linac parameters, which can be useful in the design such linacs, are derived.
	Slides WEODS1 [5.795 MB]

THP146	Preliminary Study of Terahertz Free-Electron Laser Oscillator Based on Electrostatic Accelerator	2393
	A.L. Wu, Q.K. Jia USTC/NSRL, Hefei, Anhui, People's Republic of China F. Wang, J. Wu SLAC, Menlo Park, California, USA
	Since the terahertz radiation sources provide wide applications in medical, industrial and material science, a compact, wavelength tunable and high-power THz source attracted much attention in many laboratories. In this paper, we give a primary study of a compact THz FEL based on electrostatic accelerator and the choice of basic design parameters is presented. The feasibility study is carried out using FELO codes. It is proved that FEL utilizing electrostatic accelerators (EA-FEL) will be a promising compact and powerful terahertz source.

TUP023	X-Band RF Photoinjector Research and Development at LLNL	859
	R.A. Marsh, S.G. Anderson, C.P.J. Barty, G.K. Beer, R.R. Cross, G.A. Deis, C.A. Ebbers, D.J. Gibson, F.V. Hartemann, T.L. Houck LLNL, Livermore, California, USA C. Adolphsen, A.E. Candel, T.S. Chu, E.N. Jongewaard, Z. Li, C. Limborg-Deprey, T.O. Raubenheimer, S.G. Tantawi, A.E. Vlieks, F. Wang, J.W. Wang, F. Zhou SLAC, Menlo Park, California, USA
	Funding: This work performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344, and funded by DHS Domestic Nuclear Detection Office In support of Compton scattering gamma-ray source efforts at LLNL, a multi-bunch test station is being developed to investigate accelerator optimization for future upgrades. This test station will enable work to explore the science and technology paths required to boost the current mono-energetic gamma-ray (MEGa-Ray) technology a higher effective repetition rate, potentially increasing the average gamma-ray brightness by two orders of magnitude. The test station will consist of a 5.5 cell X-band rf photoinjector, single accelerator section, and beam diagnostics. Beam quality must be exceedingly high in order to produce narrow-bandwidth gamma-rays, requiring a robust state of the art photoinjector. The photoinjector will be a high gradient (200 MV/m cathode field) standing wave structure, featuring a dual feed racetrack coupler, elliptical irises, and an optimized first cell length. Detailed design of the rf photoinjector for this test station is complete, and will be presented with modeling simulations, and layout plans.

TUP132	50 MW X-Band RF System for a Photoinjector Test Station at LLNL	1082
	T.L. Houck, S.G. Anderson, C.P.J. Barty, G.K. Beer, R.R. Cross, G.A. Deis, C.A. Ebbers, D.J. Gibson, F.V. Hartemann, R.A. Marsh LLNL, Livermore, California, USA C. Adolphsen, A.E. Candel, T.S. Chu, E.N. Jongewaard, Z. Li, T.O. Raubenheimer, S.G. Tantawi, A.E. Vlieks, F. Wang, J.W. Wang, F. Zhou SLAC, Menlo Park, California, USA
	Funding: This work performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344, and funded by DHS Domestic Nuclear Detection Office. In support of x-band photoinjector development efforts at LLNL, a 50 MW test station is being constructed to investigate structure and photocathode optimization for future upgrades. A SLAC XL-4 klystron capable of generating 50 MW, 1.5 microsecond pulses will be the high power RF source for the system. The timing of the laser pulse on the photocathode with the applied RF field places very stringent requirements on phase jitter and drift. To achieve these requirements, the klystron will be powered by a state of the art, solid-state, high voltage modulator. The 50 MW of RF power will be divided between the photoinjector and a traveling wave accelerator section. A high power phase shifter is located between the photoinjector and accelerator section to adjust the phasing of the electron bunches with respect to the accelerating field. A variable attenuator is included on the input of the photoinjector. The distribution system including the various x-band components is being designed and constructed. In this paper, we will present the design, layout, and status of the RF system.

THP182	Overview of Current Progress on the LLNL Nuclear Photonics Facility and Mono-energetic Gamma-ray Source	2456
	F.V. Hartemann, F. Albert, S.G. Anderson, C.P.J. Barty, A.J. Bayramian, R.R. Cross, C.A. Ebbers, D.J. Gibson, T.L. Houck, R.A. Marsh, D.P. McNabb, M. J. Messerly, C. Siders LLNL, Livermore, California, USA C. Adolphsen, T.S. Chu, E.N. Jongewaard, T.O. Raubenheimer, S.G. Tantawi, A.E. Vlieks, F. Wang, J.W. Wang SLAC, Menlo Park, California, USA
	Funding: This work performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344 A new class of gamma-ray light source based on Compton scattering is made possible by recent progress in accelerator physics and laser technology. Mono-energetic gamma-rays are produced from collisions between a high-brightness, relativistic electron beam and a high intensity laser pulse produced via chirped-pulse amplification (CPA). A precision, tunable gamma-ray source driven by a compact, high-gradient X-band linac is currently under development and construction at LLNL. High-brightness, relativistic electron bunches produced by an X-band linear accelerator designed in collaboration with SLAC will interact with a Joule-class, 10 ps, diode-pumped CPA laser pulse to generate tunable gamma-rays in the 0.5-2.5 MeV photon energy range via Compton scattering. The source will be used to conduct nuclear resonance fluorescence experiments and address a broad range of current and emerging applications in nuclear photoscience. Users include homeland security, stockpile science and surveillance, nuclear fuel assay, and waste imaging and assay. The source design, key parameters, and current status are presented, along with important applications.