2011 Particle Accelerator Conference - List of Authors (Johnson, R.P.)

Paper	Title	Page
MOP032	High Pressure RF Cavity Test at Fermilab	160
	B.T. Freemire, P.M. Hanlet, Y. Torun IIT, Chicago, Illinois, USA G. Flanagan, R.P. Johnson, M. Notani Muons, Inc, Batavia, USA M.R. Jana, A. Moretti, M. Popovic, A.V. Tollestrup, K. Yonehara Fermilab, Batavia, USA D.M. Kaplan Illinois Institute of Technology, Chicago, Illinois, USA
	Funding: Supported in part by DOE STTR grant DE-FG02-08ER86350 Operating a high gradient radio frequency cavity embedded in a strong magnetic field is an essential requirement for muon beam cooling. However, a magnetic field influences the maximum RF gradient due to focusing of dark current in the RF cavity. This problem is suppressed by filling the RF cavity with dense hydrogen gas. As the next step, we plan to explore the beam loading effect in the high pressure cavity by using a 400 MeV kinetic energy proton beam in the MuCool Test Area at Fermilab. We discuss the experimental setup and instrumentation.

MOP036	Epicyclic Twin-Helix Ionization Cooling Simulations	163
	A. Afanasev Hampton University, Hampton, Virginia, USA Y.S. Derbenev, V.S. Morozov JLAB, Newport News, Virginia, USA V. Ivanov, R.P. Johnson Muons, Inc, Batavia, USA
	Funding: Supported in part by DOE SBIR grant DE-SC0005589 Parametric-resonance Ionization Cooling (PIC) is proposed as the final 6D cooling stage of a high-luminosity muon collider. For the implementation of PIC, we earlier developed an epicyclic twin-helix channel with correlated behavior of the horizontal and vertical betatron motions and dispersion. We now insert absorber plates with short energy-recovering units located next to them at the appropriate locations in the twin-helix channel. We first demonstrate conventional ionization cooling in such a system with the optics uncorrelated. We then adjust the correlated optics state and induce a parametric resonance to study ionization cooling under the resonant condition.

MOP046	RF Breakdown Studies Using Pressurized Cavities	184
	R. Sah, A. Dudas, R.P. Johnson, M.L. Neubauer Muons, Inc, Batavia, USA M. BastaniNejad, A.A. Elmustafa Old Dominion University, Norfolk, Virginia, USA J.M. Byrd, D. Li LBNL, Berkeley, California, USA M.E. Conde, W. Gai ANL, Argonne, USA A. Moretti, M. Popovic, K. Yonehara Fermilab, Batavia, USA D. Rose Voss Scientific, Albuquerque, New Mexico, USA
	Funding: Supported in part by USDOE STTR Grant DE-FG02-08ER86352 and FRA DOE Contract DE-AC02-07CH11359 Many present and future particle accelerators are limited by the maximum electric gradient and peak surface fields that can be realized in RF cavities. Despite considerable effort, a comprehensive theory of RF breakdown has not been achieved, and mitigation techniques to improve practical maximum accelerating gradients have had only limited success. Recent studies have shown that high gradients can be achieved quickly in 805 MHz RF cavities pressurized with dense hydrogen gas without the need for long conditioning times, because the dense gas can dramatically reduce dark currents and multipacting. In this project we use this high pressure technique to suppress effects of residual gas and geometry found in evacuated cavities to isolate and study the role of the metallic surfaces in RF cavity breakdown as a function of radiofrequency and surface preparation. A 1.3-GHz RF test cell with replaceable electrodes (e.g. Mo, Cu, Be, W, and Nb) has been built, and a series of detailed experiments is planned at the Argonne Wakefield Accelerator. These experiments will be followed by additional experiments using a second test cell operating at 402.5 MHz.

MOP050	EPIC Muon Cooling Simulations using COSY INFINITY	190
	J.A. Maloney, B. Erdelyi Northern Illinois University, DeKalb, Illinois, USA A. Afanasev, R.P. Johnson Muons, Inc, Batavia, USA S.A. Bogacz, Y.S. Derbenev JLAB, Newport News, Virginia, USA V.S. Morozov ODU, Norfolk, Virginia, USA
	Next generation magnet systems needed for cooling channels in both neutrino factories and muon colliders will be innovative and complicated. Designing, simulating and optimizing these systems is a challenge. Using COSY INFINITY, a differential algebra-based code, to simulate complicated elements can allow the computation and correction of a variety of higher order effects, such as spherical and chromatic aberrations, that are difficult to address with other simulation tools. As an example, a helical dipole magnet has been implemented and simulated, and the performance of an epicyclic parametric ionization cooling system for muons is studied and compared to simulations made using G4Beamline, a GEANT4 toolkit.

TUP083	Phase and Frequency Locked Magnetrons for SRF Sources	979
	M. Popovic, A. Moretti Fermilab, Batavia, USA M.A.C. Cummings, A. Dudas, R.P. Johnson, M.L. Neubauer, R. Sah Muons, Inc, Batavia, USA
	Funding: Supported in part by STTR Grant DE-SC0002766 In order to make use of ferrite and/or garnet materials in the phase and frequency locked magnetron, for which Muons, Inc., received a Phase II award, materials must be tested in two orthogonal magnetic fields. One field is from the biasing field of the magnetron, the other from the biasing field used to control the ferrite within the anode structure of the magnetron. A test fixture was built and materials are being tested to determine their suitability. The status of those material tests are reported on in this paper.

TUP092	Multi-purpose 805 MHz Pillbox RF Cavity for Muon Acceleration Studies	1003
	G.M. Kazakevich, G. Flanagan, R.P. Johnson, M.L. Neubauer, R. Sah Muons, Inc, Batavia, USA K.C.D. Chan, A.J. Jason, S.S. Kurennoy, H.M. Miyadera, P.J. Turchi LANL, Los Alamos, New Mexico, USA A. Moretti, M. Popovic, K. Yonehara Fermilab, Batavia, USA Y. Torun IIT, Chicago, Illinois, USA
	Funding: Supported by DOE grant DE-FG-08ER86352. An 805 MHz RF pillbox cavity has been designed and constructed to investigate potential muon beam acceleration and cooling techniques. The cavity can operate in vacuum or under pressure to 100 atmospheres, at room temperature or in an LN2 bath at 77 K. The cavity is designed for easy assembly and disassembly with bolted construction using aluminum seals. The surfaces of the end walls of the cavity can be replaced with different materials such as copper, aluminum, beryllium, or molybdenum, and with different geometries such as shaped windows or grid structures. Different surface treatments such as electro polished, high-pressure water cleaned, and atomic layer deposition are being considered for testing. The cavity has been designed to fit inside the 5-Tesla solenoid in the MuCool Test Area at Fermilab. Performance of the cavity, including initial conditioning and operation in the external magnetic field will be reported.

TUP153	Fabrication and Test of Short Helical Solenoid Model Based on YBCO Tape	1118
	M. Yu, V. Lombardo, M.L. Lopes, D. Turrioni, A.V. Zlobin Fermilab, Batavia, USA G. Flanagan, R.P. Johnson Muons, Inc, Batavia, USA
	Funding: Supported in part by USDOE STTR Grant DE-FG02-07ER84825 and by Fermi Research Alliance, LLC, under contract No. DE-AC02-07CH11359 with the U.S. Department of Energy. A helical cooling channel (HCC) is a new technique proposed for six-dimensional (6D) cooling of muon beams. To achieve the optimal cooling rate, the high field section of HCC need to be developed, which suggests using High Temperature Superconductors (HTS). This paper updates the parameters of a YBCO based helical solenoid (HS) model, describes the fabrication of HS segments (double-pancake units) and the assembly of six-coil short HS model with two dummy cavity insertions. Three HS segments and the six-coil short model were tested. The results are presented and discussed.

WEP074	Correcting Aberrations in Complex Magnet Systems for Muon Cooling Channels	1615
	J.A. Maloney, B. Erdelyi Northern Illinois University, DeKalb, Illinois, USA A. Afanasev, R.P. Johnson Muons, Inc, Batavia, USA Y.S. Derbenev JLAB, Newport News, Virginia, USA V.S. Morozov ODU, Norfolk, Virginia, USA
	Funding: Supported in part by DOE SBIR grant DE-SC0005589 Designing and simulating complex magnet systems needed for cooling channels in both neutrino factories and muon colliders requires innovative techniques to correct for both chromatic and spherical aberrations. Optimizing complex systems, such as helical magnets for example, is also difficult but essential. By using COSY INFINITY, a differential algebra based code, the transfer and aberration maps can be examined to discover what critical terms have the greatest influence on these aberrations.

WEP249	Intense Muon Beams for Experiments at Project X	1951
	C.M. Ankenbrandt, R.P. Johnson, C. Y. Yoshikawa Muons, Inc, Batavia, USA V.S. Kashikhin, D.V. Neuffer Fermilab, Batavia, USA J. Miller BUphy, Boston, Massachusetts, USA R.A. Rimmer JLAB, Newport News, Virginia, USA
	Funding: Supported in part by DOE SBIR grant DE-SC00002739 A coherent approach for providing muon beams to several experiments for the intensity-frontier program at Project X is described. Concepts developed for the front end of a muon collider/neutrino factory facility, such as phase rotation and ionization cooling, are applied, but with significant differences. High-intensity experiments typically require high-duty-factor beams pulsed at a time interval commensurate with the muon lifetime. It is challenging to provide large RF voltages at high duty factor, especially in the presence of intense radiation and strong magnetic fields, which may preclude the use of superconducting RF cavities. As an alternative, cavities made of materials such as ultra-pure Al and Be, which become very good - but not super - conductors at cryogenic temperatures, can be used.

WEP273	Saddle RF Antenna H⁻ Ion Source Progress	1987
	V.G. Dudnikov, R.P. Johnson Muons, Inc, Batavia, USA S. Murray, T.R. Pennisi, M. Santana, M.P. Stockli, R.F. Welton ORNL, Oak Ridge, Tennessee, USA
	Funding: Supported in part by USDOE Contract DE-AC05-00OR22725 and STTR Grant DE-SC0002690 In this project we are developing an RF H⁻ surface plasma source (SPS) with saddle (SA) RF antenna which will provide better power efficiency for high pulsed and average current, higher brightness with longer lifetime and higher reliability. Several versions of new plasma generators with a small AlN test chamber and different antennasandmagneticfieldconfigurationsweretestedin the SNS ion source Test Stand. A prototype SA SPS was installed in the Test Stand with a larger, normal-sized SNS AlN chamber that achieved unanalyzed peak currents of up to 67 mA with an apparent efficiency of 1.6 mA/kW. Control experiments with H⁻ beam produced by SNS SPS with internal and external antennas were conducted. A new version of the RF triggering plasma source (TPS) has been designed. A Saddle antenna SPS with water cooling is being fabricated for high duty factor testing.

THP034	Accelerators for Subcritical Molten Salt Reactors	2181
	R.P. Johnson Muons, Inc, Batavia, USA C. Bowman ADNA, Los Alamos, New Mexico, USA
	Funding: Supported in part by Accelerator Technologies Inc. Accelerator parameters for subcritical reactors that have been considered in recent studies * are based on using solid nuclear fuel much like that used in all operating critical reactors as well as the thorium-burning accelerator-driven energy amplifier proposed by Rubbia et al. An attractive alternative reactor design that used molten salts was experimentally studied at ORNL in the 1960s, where a critical molten salt reactor was successfully operated using enriched U235 or U233 tetrafluoride fuels . These experiments give confidence that an accelerator-driven subcritical molten salt reactor will work as well or better than conventional reactors, having better efficiency due to their higher operating temperature and having the inherent safety of subcritical operation. Moreover, the requirements to drive a molten salt reactor are considerably relaxed compared to a solid fuel reactor, especially regarding accelerator reliability and spallation neutron targetry, to the point that the required technology exists today. http://www.er.doe.gov/hep/files/pdfs/ADSWhitePaperFinal.pdf http://wikipedia.org/wiki/Energy_amplifier * Paul N. Haubenreich and J. R. Engel, Nuc. Apps & Tech, 8, Feb. 1970

THP199	Raising Photoemission Efficiency with Surface Acoustic Waves	2492
	A. Afanasev Hampton University, Hampton, Virginia, USA R.P. Johnson Muons, Inc, Batavia, USA
	Funding: Supported in part by Muons, Inc. Current and future synchrotron radiation light sources and free electron laser facilities are in need of improvements in Electron Gun Technology, especially regarding the cost and efficiency of photoinjectors. The generation of Surface Acoustic Waves (SAW) on piezoelectric substrates is known to produce strong piezoelectric fields that propagate on the surface of the material. These fields significantly reduce the recombination probability of electrons and holes which can result in enhanced quantum efficiency of photoemission. Additional advantages are provided by the mobility of charge carriers that can be controlled by SAW. It is expected that this novel feature will result in enhanced efficiency of photocathode operation, leading to the production of intense, low emittance electron bunches at a high repetition rate using laser excitation.

Paper

Title

Page

High Pressure RF Cavity Test at Fermilab

160

B.T. Freemire, P.M. Hanlet, Y. Torun
IIT, Chicago, Illinois, USA
G. Flanagan, R.P. Johnson, M. Notani
Muons, Inc, Batavia, USA
M.R. Jana, A. Moretti, M. Popovic, A.V. Tollestrup, K. Yonehara
Fermilab, Batavia, USA
D.M. Kaplan
Illinois Institute of Technology, Chicago, Illinois, USA

Funding: Supported in part by DOE STTR grant DE-FG02-08ER86350
Operating a high gradient radio frequency cavity embedded in a strong magnetic field is an essential requirement for muon beam cooling. However, a magnetic field influences the maximum RF gradient due to focusing of dark current in the RF cavity. This problem is suppressed by filling the RF cavity with dense hydrogen gas. As the next step, we plan to explore the beam loading effect in the high pressure cavity by using a 400 MeV kinetic energy proton beam in the MuCool Test Area at Fermilab. We discuss the experimental setup and instrumentation.

MOP036

Epicyclic Twin-Helix Ionization Cooling Simulations

163

A. Afanasev
Hampton University, Hampton, Virginia, USA
Y.S. Derbenev, V.S. Morozov
JLAB, Newport News, Virginia, USA
V. Ivanov, R.P. Johnson
Muons, Inc, Batavia, USA

Funding: Supported in part by DOE SBIR grant DE-SC0005589
Parametric-resonance Ionization Cooling (PIC) is proposed as the final 6D cooling stage of a high-luminosity muon collider. For the implementation of PIC, we earlier developed an epicyclic twin-helix channel with correlated behavior of the horizontal and vertical betatron motions and dispersion. We now insert absorber plates with short energy-recovering units located next to them at the appropriate locations in the twin-helix channel. We first demonstrate conventional ionization cooling in such a system with the optics uncorrelated. We then adjust the correlated optics state and induce a parametric resonance to study ionization cooling under the resonant condition.

MOP046

RF Breakdown Studies Using Pressurized Cavities

184

R. Sah, A. Dudas, R.P. Johnson, M.L. Neubauer
Muons, Inc, Batavia, USA
M. BastaniNejad, A.A. Elmustafa
Old Dominion University, Norfolk, Virginia, USA
J.M. Byrd, D. Li
LBNL, Berkeley, California, USA
M.E. Conde, W. Gai
ANL, Argonne, USA
A. Moretti, M. Popovic, K. Yonehara
Fermilab, Batavia, USA
D. Rose
Voss Scientific, Albuquerque, New Mexico, USA

Funding: Supported in part by USDOE STTR Grant DE-FG02-08ER86352 and FRA DOE Contract DE-AC02-07CH11359
Many present and future particle accelerators are limited by the maximum electric gradient and peak surface fields that can be realized in RF cavities. Despite considerable effort, a comprehensive theory of RF breakdown has not been achieved, and mitigation techniques to improve practical maximum accelerating gradients have had only limited success. Recent studies have shown that high gradients can be achieved quickly in 805 MHz RF cavities pressurized with dense hydrogen gas without the need for long conditioning times, because the dense gas can dramatically reduce dark currents and multipacting. In this project we use this high pressure technique to suppress effects of residual gas and geometry found in evacuated cavities to isolate and study the role of the metallic surfaces in RF cavity breakdown as a function of radiofrequency and surface preparation. A 1.3-GHz RF test cell with replaceable electrodes (e.g. Mo, Cu, Be, W, and Nb) has been built, and a series of detailed experiments is planned at the Argonne Wakefield Accelerator. These experiments will be followed by additional experiments using a second test cell operating at 402.5 MHz.

MOP050

EPIC Muon Cooling Simulations using COSY INFINITY

190

J.A. Maloney, B. Erdelyi
Northern Illinois University, DeKalb, Illinois, USA
A. Afanasev, R.P. Johnson
Muons, Inc, Batavia, USA
S.A. Bogacz, Y.S. Derbenev
JLAB, Newport News, Virginia, USA
V.S. Morozov
ODU, Norfolk, Virginia, USA

Next generation magnet systems needed for cooling channels in both neutrino factories and muon colliders will be innovative and complicated. Designing, simulating and optimizing these systems is a challenge. Using COSY INFINITY, a differential algebra-based code, to simulate complicated elements can allow the computation and correction of a variety of higher order effects, such as spherical and chromatic aberrations, that are difficult to address with other simulation tools. As an example, a helical dipole magnet has been implemented and simulated, and the performance of an epicyclic parametric ionization cooling system for muons is studied and compared to simulations made using G4Beamline, a GEANT4 toolkit.

TUP083

Phase and Frequency Locked Magnetrons for SRF Sources

979

M. Popovic, A. Moretti
Fermilab, Batavia, USA
M.A.C. Cummings, A. Dudas, R.P. Johnson, M.L. Neubauer, R. Sah
Muons, Inc, Batavia, USA

Funding: Supported in part by STTR Grant DE-SC0002766
In order to make use of ferrite and/or garnet materials in the phase and frequency locked magnetron, for which Muons, Inc., received a Phase II award, materials must be tested in two orthogonal magnetic fields. One field is from the biasing field of the magnetron, the other from the biasing field used to control the ferrite within the anode structure of the magnetron. A test fixture was built and materials are being tested to determine their suitability. The status of those material tests are reported on in this paper.

TUP092

Multi-purpose 805 MHz Pillbox RF Cavity for Muon Acceleration Studies

1003

G.M. Kazakevich, G. Flanagan, R.P. Johnson, M.L. Neubauer, R. Sah
Muons, Inc, Batavia, USA
K.C.D. Chan, A.J. Jason, S.S. Kurennoy, H.M. Miyadera, P.J. Turchi
LANL, Los Alamos, New Mexico, USA
A. Moretti, M. Popovic, K. Yonehara
Fermilab, Batavia, USA
Y. Torun
IIT, Chicago, Illinois, USA

Funding: Supported by DOE grant DE-FG-08ER86352.
An 805 MHz RF pillbox cavity has been designed and constructed to investigate potential muon beam acceleration and cooling techniques. The cavity can operate in vacuum or under pressure to 100 atmospheres, at room temperature or in an LN2 bath at 77 K. The cavity is designed for easy assembly and disassembly with bolted construction using aluminum seals. The surfaces of the end walls of the cavity can be replaced with different materials such as copper, aluminum, beryllium, or molybdenum, and with different geometries such as shaped windows or grid structures. Different surface treatments such as electro polished, high-pressure water cleaned, and atomic layer deposition are being considered for testing. The cavity has been designed to fit inside the 5-Tesla solenoid in the MuCool Test Area at Fermilab. Performance of the cavity, including initial conditioning and operation in the external magnetic field will be reported.

TUP153

Fabrication and Test of Short Helical Solenoid Model Based on YBCO Tape

1118

M. Yu, V. Lombardo, M.L. Lopes, D. Turrioni, A.V. Zlobin
Fermilab, Batavia, USA
G. Flanagan, R.P. Johnson
Muons, Inc, Batavia, USA

Funding: Supported in part by USDOE STTR Grant DE-FG02-07ER84825 and by Fermi Research Alliance, LLC, under contract No. DE-AC02-07CH11359 with the U.S. Department of Energy.
A helical cooling channel (HCC) is a new technique proposed for six-dimensional (6D) cooling of muon beams. To achieve the optimal cooling rate, the high field section of HCC need to be developed, which suggests using High Temperature Superconductors (HTS). This paper updates the parameters of a YBCO based helical solenoid (HS) model, describes the fabrication of HS segments (double-pancake units) and the assembly of six-coil short HS model with two dummy cavity insertions. Three HS segments and the six-coil short model were tested. The results are presented and discussed.

WEP074

Correcting Aberrations in Complex Magnet Systems for Muon Cooling Channels

1615

J.A. Maloney, B. Erdelyi
Northern Illinois University, DeKalb, Illinois, USA
A. Afanasev, R.P. Johnson
Muons, Inc, Batavia, USA
Y.S. Derbenev
JLAB, Newport News, Virginia, USA
V.S. Morozov
ODU, Norfolk, Virginia, USA

Funding: Supported in part by DOE SBIR grant DE-SC0005589
Designing and simulating complex magnet systems needed for cooling channels in both neutrino factories and muon colliders requires innovative techniques to correct for both chromatic and spherical aberrations. Optimizing complex systems, such as helical magnets for example, is also difficult but essential. By using COSY INFINITY, a differential algebra based code, the transfer and aberration maps can be examined to discover what critical terms have the greatest influence on these aberrations.

WEP249

Intense Muon Beams for Experiments at Project X

1951

C.M. Ankenbrandt, R.P. Johnson, C. Y. Yoshikawa
Muons, Inc, Batavia, USA
V.S. Kashikhin, D.V. Neuffer
Fermilab, Batavia, USA
J. Miller
BUphy, Boston, Massachusetts, USA
R.A. Rimmer
JLAB, Newport News, Virginia, USA

Funding: Supported in part by DOE SBIR grant DE-SC00002739
A coherent approach for providing muon beams to several experiments for the intensity-frontier program at Project X is described. Concepts developed for the front end of a muon collider/neutrino factory facility, such as phase rotation and ionization cooling, are applied, but with significant differences. High-intensity experiments typically require high-duty-factor beams pulsed at a time interval commensurate with the muon lifetime. It is challenging to provide large RF voltages at high duty factor, especially in the presence of intense radiation and strong magnetic fields, which may preclude the use of superconducting RF cavities. As an alternative, cavities made of materials such as ultra-pure Al and Be, which become very good - but not super - conductors at cryogenic temperatures, can be used.

WEP273

Saddle RF Antenna H⁻ Ion Source Progress

1987

V.G. Dudnikov, R.P. Johnson
Muons, Inc, Batavia, USA
S. Murray, T.R. Pennisi, M. Santana, M.P. Stockli, R.F. Welton
ORNL, Oak Ridge, Tennessee, USA

Funding: Supported in part by USDOE Contract DE-AC05-00OR22725 and STTR Grant DE-SC0002690
In this project we are developing an RF H⁻ surface plasma source (SPS) with saddle (SA) RF antenna which will provide better power efficiency for high pulsed and average current, higher brightness with longer lifetime and higher reliability. Several versions of new plasma generators with a small AlN test chamber and different antennasandmagneticfieldconfigurationsweretestedin the SNS ion source Test Stand. A prototype SA SPS was installed in the Test Stand with a larger, normal-sized SNS AlN chamber that achieved unanalyzed peak currents of up to 67 mA with an apparent efficiency of 1.6 mA/kW. Control experiments with H⁻ beam produced by SNS SPS with internal and external antennas were conducted. A new version of the RF triggering plasma source (TPS) has been designed. A Saddle antenna SPS with water cooling is being fabricated for high duty factor testing.

THP034

Accelerators for Subcritical Molten Salt Reactors

2181

R.P. Johnson
Muons, Inc, Batavia, USA
C. Bowman
ADNA, Los Alamos, New Mexico, USA

Funding: Supported in part by Accelerator Technologies Inc.
Accelerator parameters for subcritical reactors that have been considered in recent studies * are based on using solid nuclear fuel much like that used in all operating critical reactors as well as the thorium-burning accelerator-driven energy amplifier ** proposed by Rubbia et al. An attractive alternative reactor design that used molten salts was experimentally studied at ORNL in the 1960s, where a critical molten salt reactor was successfully operated using enriched U235 or U233 tetrafluoride fuels ***. These experiments give confidence that an accelerator-driven subcritical molten salt reactor will work as well or better than conventional reactors, having better efficiency due to their higher operating temperature and having the inherent safety of subcritical operation. Moreover, the requirements to drive a molten salt reactor are considerably relaxed compared to a solid fuel reactor, especially regarding accelerator reliability and spallation neutron targetry, to the point that the required technology exists today.
* http://www.er.doe.gov/hep/files/pdfs/ADSWhitePaperFinal.pdf
** http://wikipedia.org/wiki/Energy_amplifier
*** Paul N. Haubenreich and J. R. Engel, Nuc. Apps & Tech, 8, Feb. 1970

THP199

Raising Photoemission Efficiency with Surface Acoustic Waves

2492

A. Afanasev
Hampton University, Hampton, Virginia, USA
R.P. Johnson
Muons, Inc, Batavia, USA

Funding: Supported in part by Muons, Inc.
Current and future synchrotron radiation light sources and free electron laser facilities are in need of improvements in Electron Gun Technology, especially regarding the cost and efficiency of photoinjectors. The generation of Surface Acoustic Waves (SAW) on piezoelectric substrates is known to produce strong piezoelectric fields that propagate on the surface of the material. These fields significantly reduce the recombination probability of electrons and holes which can result in enhanced quantum efficiency of photoemission. Additional advantages are provided by the mobility of charge carriers that can be controlled by SAW. It is expected that this novel feature will result in enhanced efficiency of photocathode operation, leading to the production of intense, low emittance electron bunches at a high repetition rate using laser excitation.