2011 Particle Accelerator Conference - List of Authors (Tantawi, S.G.)

Paper

Title

Page

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).

TUP102

Cryogenic RF Material Testing at SLAC

1030

J. Guo, D.W. Martin, S.G. Tantawi, C. Yoneda
SLAC, Menlo Park, California, USA

Funding: The work is supported by the US Department of Energy
We have been developing an X-band cryogenic RF material testing system since 2005. By measuring the Q of a hemispherical cavity with the material sample at is flat interchangeable bottom, the system is capable to characterize the surface resistance of different materials at the temperature of 3-300K, as well as the quenching RF magnetic field of the superconducting samples at different temperatures. Using a SLAC X-band 50 MW klystron, the system can measure the quenching H-field of up to 300mT under current setup, with the possibility of further enhancement by changing the RF distribution configuration.

THOBN5

Design and Testing of Advanced Photonic Bandgap (PBG) Accelerator Structures

2071

B.J. Munroe, M.A. Shapiro, R.J. Temkin
MIT/PSFC, Cambridge, Massachusetts, USA
V.A. Dolgashev, S.G. Tantawi, A.D. Yeremian
SLAC, Menlo Park, California, USA
R.A. Marsh
LLNL, Livermore, California, USA

Photonic Band-gap (PBG) structures continue to be an area of promising research for high gradient accelerators with wakefield suppression. Experimental results on an 11.4 GHz PBG structure tested at high power and high repetition rate at SLAC have shown that high gradients can be achieved in these structures. For PBG structures with thin rods, however, pulsed heating of the inner row of rods is a problem. Following these preliminary results, two new PBG structures have been designed. One structure, designated 1C-SW-A5.65-T4.6-Cu-PBG2-SLAC1, utilizes elliptical inner rods to reduce pulsed heating to an acceptable level; it will be tested at SLAC. A second PBG structure with round rods will be tested at 17.1 GHz at MIT. The MIT research will use the improved diagnostic access of the PBG structure to obtain a better understanding of the breakdown process. We will present preliminary results for the design and testing of these PBG structures.

Slides THOBN5 [0.752 MB]

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
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).

TUP102	Cryogenic RF Material Testing at SLAC	1030
	J. Guo, D.W. Martin, S.G. Tantawi, C. Yoneda SLAC, Menlo Park, California, USA
	Funding: The work is supported by the US Department of Energy We have been developing an X-band cryogenic RF material testing system since 2005. By measuring the Q of a hemispherical cavity with the material sample at is flat interchangeable bottom, the system is capable to characterize the surface resistance of different materials at the temperature of 3-300K, as well as the quenching RF magnetic field of the superconducting samples at different temperatures. Using a SLAC X-band 50 MW klystron, the system can measure the quenching H-field of up to 300mT under current setup, with the possibility of further enhancement by changing the RF distribution configuration.

THOBN5	Design and Testing of Advanced Photonic Bandgap (PBG) Accelerator Structures	2071
	B.J. Munroe, M.A. Shapiro, R.J. Temkin MIT/PSFC, Cambridge, Massachusetts, USA V.A. Dolgashev, S.G. Tantawi, A.D. Yeremian SLAC, Menlo Park, California, USA R.A. Marsh LLNL, Livermore, California, USA
	Photonic Band-gap (PBG) structures continue to be an area of promising research for high gradient accelerators with wakefield suppression. Experimental results on an 11.4 GHz PBG structure tested at high power and high repetition rate at SLAC have shown that high gradients can be achieved in these structures. For PBG structures with thin rods, however, pulsed heating of the inner row of rods is a problem. Following these preliminary results, two new PBG structures have been designed. One structure, designated 1C-SW-A5.65-T4.6-Cu-PBG2-SLAC1, utilizes elliptical inner rods to reduce pulsed heating to an acceptable level; it will be tested at SLAC. A second PBG structure with round rods will be tested at 17.1 GHz at MIT. The MIT research will use the improved diagnostic access of the PBG structure to obtain a better understanding of the breakdown process. We will present preliminary results for the design and testing of these PBG structures.
	Slides THOBN5 [0.752 MB]

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.