IPAC2012 - List of Keywords (brightness)

Paper	Title	Other Keywords	Page
MOPPC005	Parameter Space for the LHC Luminosity Upgrade*	luminosity, target, emittance, optics	127
	F. Zimmermann, O.S. Brüning CERN, Geneva, Switzerland
	Funding: Work supported by the European Commission under the FP7 Research Infrastructures projects EuCARD, grant agreement no. 227579, and HiLumi LHC, grant agreement no. 284404. We review the parameter space for the high-luminosity upgrade of the LHC (HL-LHC). Starting from the luminosity targets and the primary limitations, e.g., long-range beam-beam effects, event pile up, electron cloud, turnaround time, intrabeam scattering, we determine the range for compatible beam parameters such as the beam intensity, bunch spacing, transverse and longitudinal emittances, bunch length, and IP beta functions required to meet the HL-LHC goals. A selection of a few possible parameter sets is presented for comparison and discussion.

MOPPP062	Soleil Emittance Reduction using a Robinson Wiggler	photon, emittance, damping, wiggler	702
	H.B. Abualrob, P. Brunelle, M.-E. Couprie, O. Marcouillé, A. Nadji, L.S. Nadolski, R. Nagaoka SOLEIL, Gif-sur-Yvette, France
	For both synchrotron light sources as SOLEIL and colliders, the emittance is one of the key parameters to increase the photon brightness and the beam luminosity. In order to decrease the emittance, the ring optics is built on very focusing lattices leading to large chromaticities and potential reduction of the dynamics aperture and momentum transverse acceptance. Thus, some facilities have installed damping wigglers in zero dispersion straight sections to relax the optics and to reach sub-nanometer horizontal emittances. This solution requires however tens or hundreds meters of insertion devices. For storage ring equipped with zero-gradient bending magnets, an alternative solution can be given by installing a single Robinson wiggler [1] in a dispersive section enabling to divide the emittance by a factor 2. The uniqueness of this wiggler results from the presence of an alternated gradient superimposed the main periodic magnetic field. This paper recalls the concept of the wiggler, presents the expected gain for SOLEIL storage ring with the impact on the linear optics and the brightness. A preliminary magnetic design is also proposed. [1] K.W. Robinson, Phys. Rev, p. 373 (1958).

TUXB01	Progress Towards Ultimate Storage Ring Light Sources	emittance, electron, dipole, wiggler	1035
	M. Borland ANL, Argonne, USA
	Funding: Work supported by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences, under Contract No. DE-AC02-06CH11357. Developments such as the low emittance NSLS-II storage ring, followed by the even lower emittance MAX-IV ring, demonstrate that the technology of storage ring light sources has not reached full maturity. Indeed, these new sources are paving the way toward realizing diffraction-limited angstrom-wavelength storage ring light sources in the not-too-distant future. Our discussion begins with a review of recent trends and developments in storage ring design. We then survey on-going work around the world to develop concepts and designs for so-called "ultimate" storage ring light sources.
	Slides TUXB01 [3.442 MB]

TUEPPB007	A Self Consistent Multiprocessor Space Charge Algorithm that is Almost Embarrassingly Parallel	space-charge, simulation, factory, collective-effects	1128
	E.W. Nissen JLAB, Newport News, Virginia, USA B. Erdelyi Northern Illinois University, DeKalb, Illinois, USA S.L. Manikonda ANL, Argonne, USA
	Funding: Notice: Authored by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177. We present a space charge code that is self consistent, massively parallelizeable, and requires very little communication between the computer nodes; making the calculation almost embarrassingly parallel. This method is implemented in the code COSY Infinity where the differential algebras used in this code are important to the algorithm's proper functioning. The method works by calculating the self consistent charge distribution using the statistical moments of the test particles, and converting them into polynomial series coefficients. These coefficients are combined with differential algebraic integrals to form the potential, and electric fields. The result is a transfer map which contains the effects of space charge. This method allows for massive parallelization since its statistics based solver doesn’t require any binning of the particles, and only requires a vector containing the partial sums of the statistical moments for the different nodes to be passed. All other calculations are done independently. The resulting maps can be used to analyze the system using normal form analysis, as well as advance particles in numbers and at speeds that were previously impossible.

TUPPD046	Characterization of Li⁺ Alumino-Silicate Ion Source for Target Heating Experiments	ion, extraction, ion-source, space-charge	1506
	P.K. Roy, W.G. Greenway, J.W. Kwan, S.M. Lidia, P.A. Seidl, W.L. Waldron LBNL, Berkeley, California, USA D.P. Grote LLNL, Livermore, California, USA
	Funding: *This work was performed under the auspices of the U.S Department of Energy by LLNL under contract DE AC52 07NA27344, and by LBNL under contract. DE-AC02-05CH11231. The Heavy Ion Fusion Sciences (HIFS) program at Lawrence Berkeley National Laboratory will carry out warm dense matter experiments using Li⁺ ion beam with energy 1.2–3 MeV to achieve uniform heating up to 0.1–1 eV. Experiments will be done using the Neutralized Drift Compression Experiment-II (NDCX-II) facility. The NDCX-II accelerator has been designed to use a large diameter (10.9 cm) Li⁺ doped alumino-silicate source to produce short pulses of ≈93 mA beam current. Fabrication of a lithium source is complex, it is necessary to apply a higher temperature (>1200-degC) for thermionic emission, and the beam current density of this source is ~1mA/cm² in the space-charge limited regime. Li⁺ emission is lower than the other alkaline ions sources (K⁺, Cs⁺). The lifetime of this source is roughly 50 hours, when pulsed. Characterization of an operational lithium alumino-silicate ion source, including beam emittance, is presented.

TUPPD067	Experimental Facility for Measuring the Electron Energy Distribution from Photocathodes	electron, cathode, vacuum, laser	1557
	L.B. Jones, R.J. Cash, B.D. Fell, J.W. McKenzie, K.J. Middleman, B.L. Militsyn STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom H.E. Scheibler, A.S. Terekhov ISP, Novosibirsk, Russia
	ASTeC have spent several years developing a GaAs Photocathode Preparation Facility (PPF) which routinely produces cathodes with quantum efficiencies (Q.E.) up to 20% at 635 nm. The goal is to use these cathodes in high-average-current high-brightness injectors for particle accelerators. Electron injector brightness is driven by photocathode emittance, and brightness will be increased significantly by reducing the longitudinal and transverse energy spread. We are constructing an experimental system for measurement of the horizontal and transverse energy spreads at room and LN₂-temperature which accepts photocathodes from the PPF. The sample will be illuminated by a small, variable-wavelength light spot. The beam image will be projected onto a detector comprised of 3 grids which act as an energy filter, a micro-channel plate and a phosphor screen. A low-noise CCD camera will capture screen images, and the electron distribution and energy spread will be extracted through analysis of these images as a function of the grid potentials. The system will include a leak valve to progressively degrade the cathode, and thus allow its properties to be measured as a function of Q.E. Proc IPAC ’11, THPC129 (2011).

TUPPD080	Design of Ultrafast High-Brightness Electron Source	cathode, electron, gun, laser	1587
	J.H. Park, H. Bluem, J. Rathke, T. Schultheiss, A.M.M. Todd AES, Princeton, New Jersey, USA
	Funding: This work was supported by the U.S. Department of Energy, under Contract No. DE-SC0006210. Generation and preservation of ultrafast electron beams is one of the major challenges in accelerator R&D. Space charge forces play a fundamental role in emittance dilution and bunch lengthening for all high brightness beams. In order to generate and preserve the ultrafast high-brightness electron beam, transverse and longitudinal space charge effects have to be considered. Several approaches to achieving ultra-short bunches have been explored such as velocity bunching and magnetic compression. However, each option suffers drawbacks in achieving a compact ultrafast high-brightness source. We present an alternative scheme to achieve an ultrafast high-brightness electron beam using a radial bunch compression technique in an x-band photocathode RF electron gun. By compensating the path length difference with a curved cathode and using an extremely high acceleration gradient (greater than 200 MV/m), we seek to deliver 100 pC, 100 fsec bunches.

TUPPP032	Use of Multi-objective Methods for Choosing Undulators for Storage Rings	photon, undulator, target, storage-ring	1680
	M. Borland ANL, Argonne, USA
	Funding: Work supported by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences, under Contract No. DE-AC02-06CH11357. Users of storage ring light sources generally rely on undulators to provide the highest brightness. Choice of the optimal undulator period is complicated by the fact that users do not operate at a single photon energy or place equal weight on operation at all photon energies of interest. In addition, some users may be best served by a double- or triple-period revolver device. In this paper, we present a method of narrowing the choice of undulator periods based on multi-objective techniques. Applications are shown in the context of the Advanced Photon Source Upgrade.

TUPPP033	Exploration of a Tevatron-sized Ultimate Storage Ring	emittance, storage-ring, damping, sextupole	1683
	M. Borland ANL, Argonne, USA
	Funding: Work supported by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences, under Contract No. DE-AC02-06CH11357. With the Tevatron now shut down and slated for decommissioning, it is only natural to think about other possible uses for the 6.3 km tunnel. Given that the brightness of electron storage rings naively scales as radius cubed, one exciting possibility is to build a so-called ultimate storage ring light source. This paper describes a somewhat speculative exploration of this idea, showing the potential for a storage ring x-ray source of unprecedented brightness.

TUPPP037	Status of the ALS Brightness Upgrade	lattice, insertion, emittance, insertion-device	1692
	C. Steier, B.J. Bailey, A. Biocca, A.T. Black, D. Colomb, N. Li, A. Madur, S. Marks, H. Nishimura, G.C. Pappas, S. Prestemon, D. Robin, S.L. Rossi, T. Scarvie, D. Schlueter, C. Sun, W. Wan LBNL, Berkeley, California, USA
	Funding: Work supported by the U.S. Department of Energy under Contract No. DE-AC02-05CH11231. The Advanced Light Source (ALS) at Berkeley Lab while one of the earliest 3rd generation light sources remains one of the brightest sources for sof x-rays. Another multiyear upgrade of the ALS is currently under way, which includes new and replacement x-ray beamlines, a replacement of many of the original insertion devices and many upgrades to the accelerator. The accelerator upgrade that affects the ALS performance most directly is the ALS brightness upgrade, which will reduce the horizontal emittance from 6.3 to 2.2 nm (2.6 nm effective). This will result in a brightness increase by a factor of three for bendmagnet beamlines and at least a factor of two for insertion device beamlines. Magnets for this upgrade are currently under production and will be installed later this year.

WEOBB03	Computation of the Wigner Distribution for Undulator Radiation	radiation, undulator, electron, synchrotron	2149
	I.V. Bazarov, A.D. Gasbarro CLASSE, Ithaca, New York, USA
	In the effort to optimize brightness in synchrotron radiation sources, questions arise as to the most desirable electron beam parameters given a particular insertion device. With a detailed understanding of the distribution of emitted photons, the electron beam profile can be effectively matched. We have developed tools which, by way of the Wigner distribution, compute the phase space of photons radiated by an electron bunch. An explanation is provided of the workings of the code itself with mention of important algorithms that have been implemented. We demonstrate via numerical examples the Wigner distributions of the undulator radiation. In particular, it is shown that the phase space of light differs appreciably from the Gaussian distribution assumed in many analytical expressions and, therefore, the more thorough approaches should be used for computation of related quantities.
	Slides WEOBB03 [2.555 MB]

WEPPD060	A Drive Laser for Multi-bunch Photoinjector Operation	laser, electron, cathode, emittance	2657
	D.J. Gibson, C.P.J. Barty, M. J. Messerly, M.A. Prantil LLNL, Livermore, California, USA E. Cormier CELIA, Talence, France
	Funding: This work performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344 Numerous electron beam applications would benefit from increased average current without sacrificing beam brightness. Work is underway at LLNL to investigate the performance of X-band photoinjectors that would generate electron bunches at a rate matching the RF drive frequency, i.e. one bunch per RF cycle. A critical part of this effort involves development of photo-cathode drive laser technology. Here we present a new laser architecture that can generate pulse trains at repetition rates up to several GHz. This compact, fiber-based system is driven directly by the accelerator RF and so is inherently synchronized with the accelerating fields, and scales readily over a wide range of drive frequencies (L-band through X-band). The system will be required to produce 0.5 μJ, ~200 fs rise time, spatially and temporally shaped UV pulses designed to optimize the electron beam brightness. Presented is the current status of this system, producing pulses shorter than 2 ps from a cw source.

FRXBA01	Overview of Recent Progress on High Repetition Rate, High Brightness Electron Guns	gun, cathode, electron, SRF	4160
	F. Sannibale LBNL, Berkeley, California, USA
	In the last few years, the formidable results of x-ray light sources based on FELs opened the door to classes of experiments not accessible before. Operating facilities have relatively low repetition rates (~ 10-100 Hz), and the natural step forward consists in the development of FEL light sources capable of extending their rates by orders of magnitude in the MHz regime. Additionally, ERL based x-ray facilities with their promise of outstanding performance also require extremely high, GHz-class repetition rates. The development of such facilities would represent the next revolutionary step in terms of science capability. To operate such light sources, an electron injector capable of MHz/GHz repetition rates and with the brightness required by X-ray FELs or ERLs is required. Such injector presently does not exist. In response to that, many groups around the world are intensively working on different schemes and technologies that show the potential for achieving the desired results. This presentation includes a description of the requirements for such injectors, an overview of the pursued technologies, and a review of the results obtained so far by the groups active in the field.
	Slides FRXBA01 [6.290 MB]

Paper

Title

Other Keywords

Page

MOPPC005

Parameter Space for the LHC Luminosity Upgrade*

luminosity, target, emittance, optics

127

F. Zimmermann, O.S. Brüning
CERN, Geneva, Switzerland

Funding: Work supported by the European Commission under the FP7 Research Infrastructures projects EuCARD, grant agreement no. 227579, and HiLumi LHC, grant agreement no. 284404.
We review the parameter space for the high-luminosity upgrade of the LHC (HL-LHC). Starting from the luminosity targets and the primary limitations, e.g., long-range beam-beam effects, event pile up, electron cloud, turnaround time, intrabeam scattering, we determine the range for compatible beam parameters such as the beam intensity, bunch spacing, transverse and longitudinal emittances, bunch length, and IP beta functions required to meet the HL-LHC goals. A selection of a few possible parameter sets is presented for comparison and discussion.

MOPPP062

Soleil Emittance Reduction using a Robinson Wiggler

photon, emittance, damping, wiggler

702

H.B. Abualrob, P. Brunelle, M.-E. Couprie, O. Marcouillé, A. Nadji, L.S. Nadolski, R. Nagaoka
SOLEIL, Gif-sur-Yvette, France

For both synchrotron light sources as SOLEIL and colliders, the emittance is one of the key parameters to increase the photon brightness and the beam luminosity. In order to decrease the emittance, the ring optics is built on very focusing lattices leading to large chromaticities and potential reduction of the dynamics aperture and momentum transverse acceptance. Thus, some facilities have installed damping wigglers in zero dispersion straight sections to relax the optics and to reach sub-nanometer horizontal emittances. This solution requires however tens or hundreds meters of insertion devices. For storage ring equipped with zero-gradient bending magnets, an alternative solution can be given by installing a single Robinson wiggler [1] in a dispersive section enabling to divide the emittance by a factor 2. The uniqueness of this wiggler results from the presence of an alternated gradient superimposed the main periodic magnetic field. This paper recalls the concept of the wiggler, presents the expected gain for SOLEIL storage ring with the impact on the linear optics and the brightness. A preliminary magnetic design is also proposed. [1] K.W. Robinson, Phys. Rev, p. 373 (1958).

TUXB01

Progress Towards Ultimate Storage Ring Light Sources

emittance, electron, dipole, wiggler

1035

M. Borland
ANL, Argonne, USA

Funding: Work supported by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences, under Contract No. DE-AC02-06CH11357.
Developments such as the low emittance NSLS-II storage ring, followed by the even lower emittance MAX-IV ring, demonstrate that the technology of storage ring light sources has not reached full maturity. Indeed, these new sources are paving the way toward realizing diffraction-limited angstrom-wavelength storage ring light sources in the not-too-distant future. Our discussion begins with a review of recent trends and developments in storage ring design. We then survey on-going work around the world to develop concepts and designs for so-called "ultimate" storage ring light sources.

Slides TUXB01 [3.442 MB]

TUEPPB007

A Self Consistent Multiprocessor Space Charge Algorithm that is Almost Embarrassingly Parallel

space-charge, simulation, factory, collective-effects

1128

E.W. Nissen
JLAB, Newport News, Virginia, USA
B. Erdelyi
Northern Illinois University, DeKalb, Illinois, USA
S.L. Manikonda
ANL, Argonne, USA

Funding: Notice: Authored by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177.
We present a space charge code that is self consistent, massively parallelizeable, and requires very little communication between the computer nodes; making the calculation almost embarrassingly parallel. This method is implemented in the code COSY Infinity where the differential algebras used in this code are important to the algorithm's proper functioning. The method works by calculating the self consistent charge distribution using the statistical moments of the test particles, and converting them into polynomial series coefficients. These coefficients are combined with differential algebraic integrals to form the potential, and electric fields. The result is a transfer map which contains the effects of space charge. This method allows for massive parallelization since its statistics based solver doesn’t require any binning of the particles, and only requires a vector containing the partial sums of the statistical moments for the different nodes to be passed. All other calculations are done independently. The resulting maps can be used to analyze the system using normal form analysis, as well as advance particles in numbers and at speeds that were previously impossible.

TUPPD046

Characterization of Li⁺ Alumino-Silicate Ion Source for Target Heating Experiments

ion, extraction, ion-source, space-charge

1506

P.K. Roy, W.G. Greenway, J.W. Kwan, S.M. Lidia, P.A. Seidl, W.L. Waldron
LBNL, Berkeley, California, USA
D.P. Grote
LLNL, Livermore, California, USA

Funding: *This work was performed under the auspices of the U.S Department of Energy by LLNL under contract DE AC52 07NA27344, and by LBNL under contract. DE-AC02-05CH11231.
The Heavy Ion Fusion Sciences (HIFS) program at Lawrence Berkeley National Laboratory will carry out warm dense matter experiments using Li⁺ ion beam with energy 1.2–3 MeV to achieve uniform heating up to 0.1–1 eV. Experiments will be done using the Neutralized Drift Compression Experiment-II (NDCX-II) facility. The NDCX-II accelerator has been designed to use a large diameter (10.9 cm) Li⁺ doped alumino-silicate source to produce short pulses of ≈93 mA beam current. Fabrication of a lithium source is complex, it is necessary to apply a higher temperature (>1200-degC) for thermionic emission, and the beam current density of this source is ~1mA/cm² in the space-charge limited regime. Li⁺ emission is lower than the other alkaline ions sources (K⁺, Cs⁺). The lifetime of this source is roughly 50 hours, when pulsed. Characterization of an operational lithium alumino-silicate ion source, including beam emittance, is presented.

TUPPD067

Experimental Facility for Measuring the Electron Energy Distribution from Photocathodes

electron, cathode, vacuum, laser

1557

L.B. Jones, R.J. Cash, B.D. Fell, J.W. McKenzie, K.J. Middleman, B.L. Militsyn
STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom
H.E. Scheibler, A.S. Terekhov
ISP, Novosibirsk, Russia

ASTeC have spent several years developing a GaAs Photocathode Preparation Facility (PPF) which routinely produces cathodes with quantum efficiencies (Q.E.) up to 20% at 635 nm*. The goal is to use these cathodes in high-average-current high-brightness injectors for particle accelerators. Electron injector brightness is driven by photocathode emittance, and brightness will be increased significantly by reducing the longitudinal and transverse energy spread. We are constructing an experimental system for measurement of the horizontal and transverse energy spreads at room and LN₂-temperature which accepts photocathodes from the PPF. The sample will be illuminated by a small, variable-wavelength light spot. The beam image will be projected onto a detector comprised of 3 grids which act as an energy filter, a micro-channel plate and a phosphor screen. A low-noise CCD camera will capture screen images, and the electron distribution and energy spread will be extracted through analysis of these images as a function of the grid potentials. The system will include a leak valve to progressively degrade the cathode, and thus allow its properties to be measured as a function of Q.E.
* Proc IPAC ’11, THPC129 (2011).

TUPPD080

Design of Ultrafast High-Brightness Electron Source

cathode, electron, gun, laser

1587

J.H. Park, H. Bluem, J. Rathke, T. Schultheiss, A.M.M. Todd
AES, Princeton, New Jersey, USA

Funding: This work was supported by the U.S. Department of Energy, under Contract No. DE-SC0006210.
Generation and preservation of ultrafast electron beams is one of the major challenges in accelerator R&D. Space charge forces play a fundamental role in emittance dilution and bunch lengthening for all high brightness beams. In order to generate and preserve the ultrafast high-brightness electron beam, transverse and longitudinal space charge effects have to be considered. Several approaches to achieving ultra-short bunches have been explored such as velocity bunching and magnetic compression. However, each option suffers drawbacks in achieving a compact ultrafast high-brightness source. We present an alternative scheme to achieve an ultrafast high-brightness electron beam using a radial bunch compression technique in an x-band photocathode RF electron gun. By compensating the path length difference with a curved cathode and using an extremely high acceleration gradient (greater than 200 MV/m), we seek to deliver 100 pC, 100 fsec bunches.

TUPPP032

Use of Multi-objective Methods for Choosing Undulators for Storage Rings

photon, undulator, target, storage-ring

1680

M. Borland
ANL, Argonne, USA

Funding: Work supported by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences, under Contract No. DE-AC02-06CH11357.
Users of storage ring light sources generally rely on undulators to provide the highest brightness. Choice of the optimal undulator period is complicated by the fact that users do not operate at a single photon energy or place equal weight on operation at all photon energies of interest. In addition, some users may be best served by a double- or triple-period revolver device. In this paper, we present a method of narrowing the choice of undulator periods based on multi-objective techniques. Applications are shown in the context of the Advanced Photon Source Upgrade.

TUPPP033

Exploration of a Tevatron-sized Ultimate Storage Ring

emittance, storage-ring, damping, sextupole

1683

M. Borland
ANL, Argonne, USA

Funding: Work supported by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences, under Contract No. DE-AC02-06CH11357.
With the Tevatron now shut down and slated for decommissioning, it is only natural to think about other possible uses for the 6.3 km tunnel. Given that the brightness of electron storage rings naively scales as radius cubed, one exciting possibility is to build a so-called ultimate storage ring light source. This paper describes a somewhat speculative exploration of this idea, showing the potential for a storage ring x-ray source of unprecedented brightness.

TUPPP037

Status of the ALS Brightness Upgrade

lattice, insertion, emittance, insertion-device

1692

C. Steier, B.J. Bailey, A. Biocca, A.T. Black, D. Colomb, N. Li, A. Madur, S. Marks, H. Nishimura, G.C. Pappas, S. Prestemon, D. Robin, S.L. Rossi, T. Scarvie, D. Schlueter, C. Sun, W. Wan
LBNL, Berkeley, California, USA

Funding: Work supported by the U.S. Department of Energy under Contract No. DE-AC02-05CH11231.
The Advanced Light Source (ALS) at Berkeley Lab while one of the earliest 3rd generation light sources remains one of the brightest sources for sof x-rays. Another multiyear upgrade of the ALS is currently under way, which includes new and replacement x-ray beamlines, a replacement of many of the original insertion devices and many upgrades to the accelerator. The accelerator upgrade that affects the ALS performance most directly is the ALS brightness upgrade, which will reduce the horizontal emittance from 6.3 to 2.2 nm (2.6 nm effective). This will result in a brightness increase by a factor of three for bendmagnet beamlines and at least a factor of two for insertion device beamlines. Magnets for this upgrade are currently under production and will be installed later this year.

WEOBB03

Computation of the Wigner Distribution for Undulator Radiation

radiation, undulator, electron, synchrotron

2149

I.V. Bazarov, A.D. Gasbarro
CLASSE, Ithaca, New York, USA

In the effort to optimize brightness in synchrotron radiation sources, questions arise as to the most desirable electron beam parameters given a particular insertion device. With a detailed understanding of the distribution of emitted photons, the electron beam profile can be effectively matched. We have developed tools which, by way of the Wigner distribution, compute the phase space of photons radiated by an electron bunch. An explanation is provided of the workings of the code itself with mention of important algorithms that have been implemented. We demonstrate via numerical examples the Wigner distributions of the undulator radiation. In particular, it is shown that the phase space of light differs appreciably from the Gaussian distribution assumed in many analytical expressions and, therefore, the more thorough approaches should be used for computation of related quantities.

Slides WEOBB03 [2.555 MB]

WEPPD060

A Drive Laser for Multi-bunch Photoinjector Operation

laser, electron, cathode, emittance

2657

D.J. Gibson, C.P.J. Barty, M. J. Messerly, M.A. Prantil
LLNL, Livermore, California, USA
E. Cormier
CELIA, Talence, France

Funding: This work performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344
Numerous electron beam applications would benefit from increased average current without sacrificing beam brightness. Work is underway at LLNL to investigate the performance of X-band photoinjectors that would generate electron bunches at a rate matching the RF drive frequency, i.e. one bunch per RF cycle. A critical part of this effort involves development of photo-cathode drive laser technology. Here we present a new laser architecture that can generate pulse trains at repetition rates up to several GHz. This compact, fiber-based system is driven directly by the accelerator RF and so is inherently synchronized with the accelerating fields, and scales readily over a wide range of drive frequencies (L-band through X-band). The system will be required to produce 0.5 μJ, ~200 fs rise time, spatially and temporally shaped UV pulses designed to optimize the electron beam brightness. Presented is the current status of this system, producing pulses shorter than 2 ps from a cw source.

FRXBA01

Overview of Recent Progress on High Repetition Rate, High Brightness Electron Guns

gun, cathode, electron, SRF

4160

F. Sannibale
LBNL, Berkeley, California, USA

In the last few years, the formidable results of x-ray light sources based on FELs opened the door to classes of experiments not accessible before. Operating facilities have relatively low repetition rates (~ 10-100 Hz), and the natural step forward consists in the development of FEL light sources capable of extending their rates by orders of magnitude in the MHz regime. Additionally, ERL based x-ray facilities with their promise of outstanding performance also require extremely high, GHz-class repetition rates. The development of such facilities would represent the next revolutionary step in terms of science capability. To operate such light sources, an electron injector capable of MHz/GHz repetition rates and with the brightness required by X-ray FELs or ERLs is required. Such injector presently does not exist. In response to that, many groups around the world are intensively working on different schemes and technologies that show the potential for achieving the desired results. This presentation includes a description of the requirements for such injectors, an overview of the pursued technologies, and a review of the results obtained so far by the groups active in the field.

Slides FRXBA01 [6.290 MB]