2011 Particle Accelerator Conference - List of Keywords (brightness)

Paper	Title	Other Keywords	Page
MOP208	Baseline Suppression Problems for High Precision Measurements Using Optical Beam Profile Monitors.	background, controls, radiation, monitoring	486
	P. Thieberger, D.M. Gassner, J.W. Glenn, M.G. Minty, C.M. Zimmer BNL, Upton, Long Island, New York, USA
	Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy. The use of fluorescent screens for beam profile monitors provides a simple and widely used way to obtain detailed two dimensional intensity maps. For high precision measurements many possible error contributions need to be considered that have to do with properties of the fluorescent screens and of the CCDs. Saturation effects, reflections within and outside the screen, non-linearities, radiation damage, etc are often mentioned. Here we concentrate on an error source less commonly described, namely erroneous baseline subtraction, which is particularly important when fitting projected images. We show computer simulations as well as measurement results having remarkable sensitivity of the fitted profile widths to even partial suppression of the profile baseline data, which often arises from large pixel-to-pixel variations at low intensity levels. Such inadvertent baseline data suppression is very easy to miss as it is usually not obvious when inspecting projected profiles. In this report we illustrate this effect and discuss possible algorithms to automate the detection of this problem as well as some possible corrective measures.

MOP231	Absolute Beam Flux Measurement at NDCX-I Using Gold-Melting-Calorimetry Technique	ion, monitoring, heavy-ion, laser	540
	P.N. Ni, F.M. Bieniosek, S.M. Lidia LBNL, Berkeley, California, USA J.R. Welch Cornell University, Ithaca, New York, USA
	Funding: Supported by the U.S. Department of Energy under Contracts No. DE-AC02-05CH11231 and DE-AC52-07NA27344. We report on an alternative way to measure beam fluence at NDCX-I, which is necessary for numerical simulation and planning of warm-dense-matter (WDM) experiments. So far the NDCX-I beam fluence has been characterized using a fast Faraday cup, radiation from a scintillator and tungsten foil calorimeter techniques. The present beam intensity is sufficient to melt and partially evaporate a 150 nm thick gold foil. Thermal emission (function of temperature) of the gold foil in the visible spectrum was measured during beam irradiation. A distinct shelf in the thermal emission intensity was observed after 600 ns, indicating that the sample reached the melting temperature. Using known heat capacity and latent heat of melting, the beam flux fully determines the duration of the melting shelf and the moment it appears. Using this technique we estimate an average 260 kW/cm² beam flux over 10μs, which is consistent with values provided by the other methods.

TUOCS2	Accelerator Aspects of the Advance Photon Source Upgrade	undulator, photon, lattice, radiation	766
	L. Emery, M. Borland, G. Decker, K.C. Harkay, E.R. Moog, R. Nassiri 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. The Advanced Photon Source (APS) is a third-generation storage-ring-based x-ray source that has been operating for more than 13 years and is enjoying a long period of stable, reliable operation. While APS is presently providing state-of-the-art performance to its large user community, we must plan for improvements and upgrades to stay at the forefront scientifically. Significant improvements should be possible through upgrades of beamline optics, detectors, and end-station equipment. In this paper, we discuss the evolutionary changes that are envisioned for the storage ring itself. These include short-pulse x-rays, long straight sections, superconducting undulators, improved beam stability, and higher current. With these and other changes, we anticipate significant improvements in capacity, flux, and brightness, along with the ability to perform unique time-resolved experiments.
	Slides TUOCS2 [0.932 MB]

TUOCS3	Status of the ALS Upgrade	lattice, emittance, insertion, insertion-device	769
	C. Steier, B.J. Bailey, A. Biocca, A.T. Black, D. Colomb, N. Li, A. Madur, S. Marks, H. Nishimura, G.C. Pappas, G.J. Portmann, S. Prestemon, D. Robin, S.L. Rossi, F. Sannibale, 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 is one of the earliest 3rd generation light sources. Over the years substantial upgrades have been implemented to keep the facility at the forefront of soft x-ray sources. The most recent one is a multi-year upgrade, that 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. This will result in a brightness increase by a factor of three for bend magnet beamlines and at least a factor of two for insertion device beamlines and will keep the ALS competitive with newer sources.
	Slides TUOCS3 [4.970 MB]

TUP016	Beam Brightness Booster with Charge Exchange Injection and Superintense Circulating Beams Production	ion, electron, proton, target	844
	V.G. Dudnikov, C.M. Ankenbrandt Muons, Inc, Batavia, USA
	An increase of intensity and brightness of proton beam by means of charge exchange injection and devices developed for this experiment are considered. First observation of e-p instability, explanation and damping by feed back are discussed. Discovery of “cesiation effect” leading to multiple increase of negative ion emission from gas discharges and development of surface-plasma sources for intense high brightness negative ion beams production are considered. By these developments were prepared a possibility for production of stable “superintense” circulating beam with intensity and brightness fare above space charge limit. A beam brightness booster (BBB) for significant increase of accumulated beam brightness is discussed. New opportunity for simplification of the superintense beam production is promised by developing of nonlinear close to integrable focusing system with broad spread of betatron tune and the broad bend feed back system for e-p instability suppression.

TUP124	Phase Contrast Imaging Using a Single Picosecond X-ray Pulse of the Inverse Compton Source at the BNL Accelerator Test Facility	photon, electron, scattering, laser	1062
	M. Carpinelli Università di Sassari and INFN, Sassari, Italy P. Delogu, M. Endrizzi INFN-Pisa, Pisa, Italy B. Golosio, P. Oliva INFN-Cagliari, Monserrato (Cagliari), Italy I. Pogorelsky, V. Yakimenko BNL, Upton, Long Island, New York, USA
	Inverse Compton scattering (ICS) X-ray sources are of current interest due to their novel features that enable new methods in medical and biological imaging. As a compelling example of such a possibility, we present an experimental demonstration of single shot inline phase contrast imaging using the ICS source located at the BNL Accelerator Test Facility. The phase contrast effect is clearly observed in the images obtained. Further, its qualities are shown to be in agreement with the predictions of theoretical models through comparison of experimental and simulated images of a set of plastic wires of differing composition and size. We also display an example of application of the technique to single shot phase contrast imaging of a biological sample.

WEP133	Adaptive Space-charge Meshing in the General Particle Tracer Code	space-charge, electron, simulation, injection	1728
	S.B. van der Geer Pulsar Physics, Eindhoven, The Netherlands O.J. Luiten, M.J. de Loos TUE, Eindhoven, The Netherlands G. Pöplau, U. van Rienen Rostock University, Faculty of Computer Science and Electrical Engineering, Rostock, Germany
	Efficient and accurate space-charge calculations are essential for the design of high-brightness charged particle sources. Space-charge calculations in the General Particle Tracer (GPT) code make use of an efficient multigrid Poisson solver developed for non-equidistant meshes at Rostock University. GPT uses aggressive mesh-adaptation with highly non-equidistant spacing to speed up calcula- tion time, where the mesh line positions are based upon the projected charge density. Here we present a new meshing scheme where the solution of an intermediate step in the multigrid algorithm is used to define optimal mesh line positions. An analytical test case and comparison with a molecular dynamics calculation of an ultrafast electron diffraction experiment demonstrate the capabilities of this new algorithm in the GPT code.

WEP157	An Implementation of the Fast Multipole Method for High Accuracy Particle Tracking of Intense Beams	multipole, space-charge, simulation, hadron	1782
	E.W. Nissen, B. Erdelyi Northern Illinois University, DeKalb, Illinois, USA
	We implement a single level version of the fast multipole method in the software package COSY Infinity. This algorithm has been used in other physics fields to determine high accuracy electrostatic potentials, and is implemented here for charged particle beams. The method scales like NlogN with the particle number and has a priori error estimates, which can be reduced to essentially machine precision if multipole expansions of high enough order are employed, resulting in a highly accurate algorithm for simulation of intense beams without averaging such as encountered in PIC methods. In order to further speed up the algorithm we use COSY Infinity’s innate differential algebraic methods to help with the expansions inherent in this system. Differential algebras allow for fast and exact numerical differentiation of functions that carries through any mathematical transformations performed, and can be used to quickly create the expansions used in the fast multipole method. This can then be combined with moment method techniques to extract transfer maps which include space charge within distributions that are difficult to approximate.

WEP160	Inclusion of Surface Roughness Effects in Emission Modeling With the MICHELLE Code	cathode, electron, space-charge, emittance	1788
	J.F. DeFord STAAR/AWR Corporation, Mequon, USA N.J. Dionne, S.G. Ovtchinnikov, J.J. Petillo SAIC, Burlington, Massachusetts, USA
	High-brightness electron beams are needed in millimeter-wave tubes and other high-power RF applications. Cathode surface roughness at the micron scale, commonly due to machining or other effects, can lead to broadening of the velocity distribution of electrons downstream, increasing emittance and lowering beam brightness. In this paper we investigate methods of including surface roughness effects in the MICHELLE code. Modeling of typical surface imperfections over an entire cathode is not feasible, since it requires representation of features that are 3 to 5 orders of magnitude smaller than the cathode. Moreover, the actual surface imperfections for a given cathode are unknown without a prohibitive microscopic investigation of the surface, and these details vary between cathodes with the same machining history. To avoid these problems we investigated modifications to emission models that can account for these effects in an average sense, allowing the use of a smooth emission surface in a model while retaining the essential effects of the rough surface on the beam. We present the results of this investigation, along with representative solutions for sample structures. John Petillo, et al., “Recent Developments in the MICHELLE 2D/3D Electron Gun and Collector Modeling Code”, IEEE Trans. Electron Devices Sci., vol. 52, no. 5, May 2005, pp. 742-748.

WEP170	Inspection Camera for Superconducting Cavity at IHEP	cavity, superconducting-cavity, background, focusing	1808
	Z.C. Liu, J. Gao, Z.Q. Li IHEP Beijing, Beijing, People's Republic of China
	The first 1.3GHz low-loss large grain 9-cell superconducting cavity for ILC was fabricated at the Institute of High Energy Physics (IHEP) in April, 2010. The gradient of the cavity reached 20MV/m on the first vertical test in KEK in June, 2010. The gradient was limited by quench and field emission of the ninth-cell of the cavity. To locate the position of defects and improve surface processing, we have developed a high resolution inspection camera for the 1.3GHz 9-cell superconducting cavity of IHEP to check the cavity surface and make comparison. The camera is suitable for single and multi-cell 1.3GHz superconducting cavities. As there are several types of cavity under developing in IHEP, the camera was designed to be suitable for different type and frequency cavities like 500MHz BEPC II superconducting cavity, 1.3GHz TESLA and TESLA-like cavity, 1.3GHz and 650MHz low-beta cavity.

WEP281	Beam Imaging of a High-Brightness Elliptic Electron Gun	electron, gun, simulation, focusing	2008
	T.M. Bemis, C. Chen, M.H. Lawrence, J.Z. Zhou Beam Power Technology, Inc., Chelmsford, MA, USA
	Funding: This work was funded in part by the Department of Energy, Grant No. DE-FG02-07ER84910. An innovative research program is being carried out to experimentally demonstrate a high-brightness, space-charge-dominated elliptic electron beam using a non-axisymmetric permanent magnet focusing system. Results of the fabrication, initial testing and beam imaging of an elliptic electron gun are reported. Good agreement is found between the experimental measurements and simulation.

THP007	FEL Potential of eRHIC	FEL, electron, linac, SRF	2151
	V. Litvinenko, I. Ben-Zvi, Y. Hao, C.C. Kao, D. Kayran, J.B. Murphy, V. Ptitsyn, T. Roser, D. Trbojevic, N. Tsoupas BNL, Upton, Long Island, New York, USA
	Brookhaven National Laboratory plans to build a 5-to-30 GeV energy-recovery linac (ERL) for its future electron-ion collider, eRHIC. In past few months, the Laboratory turned its attention to the potential of this unique machine for free electron lasers (FELS), which we initially assessed earlier. In this paper, we present our current vision of a possible FEL farm, and of narrow-band FEL-oscillators driven by this accelerator. V.N. Litvinenko, I. Ben-Zvi, Proceedings of FEL'2004, http://jacow.org/f04/papers/WEBOS04/

THP114	Status of the PEP-X Light Source Design Study	emittance, photon, FEL, linac	2336
	R.O. Hettel, K.L.F. Bane, K.J. Bertsche, Y. Cai, A. Chao, X. Huang, Y. Jiao, C.-K. Ng, Y. Nosochkov, A. Novokhatski, T. Rabedeau, C.H. Rivetta, J.A. Safranek, G.V. Stupakov, L. Wang, M.-H. Wang, L. Xiao SLAC, Menlo Park, California, USA
	Funding: Work supported in part by Department of Energy Contract DE-AC02-76SF00515 and Office of Basic Energy Sciences, Division of Chemical Sciences. The SLAC Beam Physics group and collaborators continue to study options for implementing a near diffraction-limited ring-based light source in the 2.2-km PEP-II tunnel that will serve the SSRL scientific program in the future. The study team has completed the baseline design for a 4.5-GeV storage ring having 160-pm-rad emittance with stored beam current of 1.5 A, providing >10²² brightness for multi-keV photon beams from 3.5-m undulator sources. The team is now investigating possible 5-GeV ERL configurations which, similar to the Cornell and KEK ERL plans, would have ~30 pm-rad emittance with 100 mA current, and ~10 pm-rad emittance with 25 mA or less. In the next year, a diffraction-limited storage ring using on-axis injection in order to reach 30 pm-rad or less emittance will be investigated. An overview of the PEP-X design study and SSRL’s plans for defining the performance parameters that will guide the choice of implementation options is presented.

THP120	Light Sources Optimized with Super Bends	dipole, storage-ring, emittance, photon	2342
	L. Emery ANL, Argonne, USA C. Steier LBNL, Berkeley, California, USA
	Funding: Work at Argonne was supported by U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences, under contract No. DE-AC02-06CH11357 In the past small storage rings with dipole-magnet-only sources were called second-generation light sources (before insertion devices (IDs) were used). With today's technology, e.g. superconducting dipole magnet of 5 T (e.g., ALS's Superbend ), one could make a smaller ring (say, 60-m circumference) with substantial brightness for dipole-magnet beams. Without IDs, these optimized sources would be designated as between second and third generation. Such rings don't exist yet, but their concept can be compared with other types of compact light sources. Typical parameters of such ring would be 60-m circumference, 2 GeV, several 5-T dipole sources in TME-like cells, and 4x10¹³ photons/s/0.1% BW at 1 Angstrom. The number of beamlines is variable, but potentially very large, only limited by funding. D. Robin et al., NIM A 538, 1-3, (2005), 65-92.

THP140	Synchrotron Light Options at Super-B	photon, radiation, undulator, synchrotron	2384
	W. Wittmer, Y. Nosochkov, A. Novokhatski, J.T. Seeman, M.K. Sullivan SLAC, Menlo Park, California, USA M.E. Biagini, P. Raimondi INFN/LNF, Frascati (Roma), Italy
	The Super-B facility will collide electron and positron beams with different characteristics as done in the past at PEP-II and KEKB. The ring and electron (positron) beam characteristic of both high and low energy rings of the Super-B are comparable to NSLS-II and other state of the art synchrotron light sources. This suggests the use of this facility, either parasitically or in dedicated runs, as light source. In this paper we compare the characteristics of the synchrotron light generated at Super-B with existing, in construction and proposed facilities. We investigate different schemes to incorporate the generation of synchrotron radiation in the collider lattice design and look at different beam line layouts for users.

FROAN3	High-Intensity, High-Brightness Polarized and Unpolarized Beam Production in Charge- Exchange Collisions	ion, proton, polarization, solenoid	2555
	A. Zelenski, G. Atoian, J. Ritter, D. Steski, V. Zubets BNL, Upton, Long Island, New York, USA V.I. Davydenko, A.V. Ivanov, V.V. Kolmogorov BINP SB RAS, Novosibirsk, Russia
	Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy. Basic limitations on the high-intensity H⁻ ion beam production were experimentally studied in charge-exchange collisions of the neutral atomic hydrogen beam in the Na- vapor jet ionizer cell. These studies are the part of the polarized source upgrade (to 10 mA peak current and 85% polarization) project for RHIC. In the source the atomic hydrogen beam of a 3-5 keV energy and total (equivalent) current up to 5 A is produced by neutralization of proton beam in pulsed hydrogen gas target. Formation of the proton beam (from the surface of the plasma emitter with a low transverse ion temperature ~0.2 eV) is produced by four-electrode spherical multi-aperture ion-optical system with geometrical focusing. The hydrogen atomic beam intensity up to 1.0 A /cm² (equivalent) was obtained in the Na-jet ionizer aperture of a 2.0 cm diameter. At the first stage of the experiment H⁻ beam with 36 mA current, 5 keV energy and ~1.0 cm-mrad normalized emittance was obtained using the flat grids and magnetic focusing. The experimental results of the high-intensity neutral hydrogen beam generation and studies of the charge-exchange polarization processes of this intense beam will be presented.
	Slides FROAN3 [6.093 MB]

Paper

Title

Other Keywords

Page

MOP208

Baseline Suppression Problems for High Precision Measurements Using Optical Beam Profile Monitors.

background, controls, radiation, monitoring

486

P. Thieberger, D.M. Gassner, J.W. Glenn, M.G. Minty, C.M. Zimmer
BNL, Upton, Long Island, New York, USA

Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy.
The use of fluorescent screens for beam profile monitors provides a simple and widely used way to obtain detailed two dimensional intensity maps. For high precision measurements many possible error contributions need to be considered that have to do with properties of the fluorescent screens and of the CCDs. Saturation effects, reflections within and outside the screen, non-linearities, radiation damage, etc are often mentioned. Here we concentrate on an error source less commonly described, namely erroneous baseline subtraction, which is particularly important when fitting projected images. We show computer simulations as well as measurement results having remarkable sensitivity of the fitted profile widths to even partial suppression of the profile baseline data, which often arises from large pixel-to-pixel variations at low intensity levels. Such inadvertent baseline data suppression is very easy to miss as it is usually not obvious when inspecting projected profiles. In this report we illustrate this effect and discuss possible algorithms to automate the detection of this problem as well as some possible corrective measures.

MOP231

Absolute Beam Flux Measurement at NDCX-I Using Gold-Melting-Calorimetry Technique

ion, monitoring, heavy-ion, laser

540

P.N. Ni, F.M. Bieniosek, S.M. Lidia
LBNL, Berkeley, California, USA
J.R. Welch
Cornell University, Ithaca, New York, USA

Funding: Supported by the U.S. Department of Energy under Contracts No. DE-AC02-05CH11231 and DE-AC52-07NA27344.
We report on an alternative way to measure beam fluence at NDCX-I, which is necessary for numerical simulation and planning of warm-dense-matter (WDM) experiments. So far the NDCX-I beam fluence has been characterized using a fast Faraday cup, radiation from a scintillator and tungsten foil calorimeter techniques. The present beam intensity is sufficient to melt and partially evaporate a 150 nm thick gold foil. Thermal emission (function of temperature) of the gold foil in the visible spectrum was measured during beam irradiation. A distinct shelf in the thermal emission intensity was observed after 600 ns, indicating that the sample reached the melting temperature. Using known heat capacity and latent heat of melting, the beam flux fully determines the duration of the melting shelf and the moment it appears. Using this technique we estimate an average 260 kW/cm² beam flux over 10μs, which is consistent with values provided by the other methods.

TUOCS2

Accelerator Aspects of the Advance Photon Source Upgrade

undulator, photon, lattice, radiation

766

L. Emery, M. Borland, G. Decker, K.C. Harkay, E.R. Moog, R. Nassiri
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.
The Advanced Photon Source (APS) is a third-generation storage-ring-based x-ray source that has been operating for more than 13 years and is enjoying a long period of stable, reliable operation. While APS is presently providing state-of-the-art performance to its large user community, we must plan for improvements and upgrades to stay at the forefront scientifically. Significant improvements should be possible through upgrades of beamline optics, detectors, and end-station equipment. In this paper, we discuss the evolutionary changes that are envisioned for the storage ring itself. These include short-pulse x-rays, long straight sections, superconducting undulators, improved beam stability, and higher current. With these and other changes, we anticipate significant improvements in capacity, flux, and brightness, along with the ability to perform unique time-resolved experiments.

Slides TUOCS2 [0.932 MB]

TUOCS3

Status of the ALS Upgrade

lattice, emittance, insertion, insertion-device

769

C. Steier, B.J. Bailey, A. Biocca, A.T. Black, D. Colomb, N. Li, A. Madur, S. Marks, H. Nishimura, G.C. Pappas, G.J. Portmann, S. Prestemon, D. Robin, S.L. Rossi, F. Sannibale, 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 is one of the earliest 3rd generation light sources. Over the years substantial upgrades have been implemented to keep the facility at the forefront of soft x-ray sources. The most recent one is a multi-year upgrade, that 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. This will result in a brightness increase by a factor of three for bend magnet beamlines and at least a factor of two for insertion device beamlines and will keep the ALS competitive with newer sources.

Slides TUOCS3 [4.970 MB]

TUP016

Beam Brightness Booster with Charge Exchange Injection and Superintense Circulating Beams Production

ion, electron, proton, target

844

V.G. Dudnikov, C.M. Ankenbrandt
Muons, Inc, Batavia, USA

An increase of intensity and brightness of proton beam by means of charge exchange injection and devices developed for this experiment are considered. First observation of e-p instability, explanation and damping by feed back are discussed. Discovery of “cesiation effect” leading to multiple increase of negative ion emission from gas discharges and development of surface-plasma sources for intense high brightness negative ion beams production are considered. By these developments were prepared a possibility for production of stable “superintense” circulating beam with intensity and brightness fare above space charge limit. A beam brightness booster (BBB) for significant increase of accumulated beam brightness is discussed. New opportunity for simplification of the superintense beam production is promised by developing of nonlinear close to integrable focusing system with broad spread of betatron tune and the broad bend feed back system for e-p instability suppression.

TUP124

Phase Contrast Imaging Using a Single Picosecond X-ray Pulse of the Inverse Compton Source at the BNL Accelerator Test Facility

photon, electron, scattering, laser

1062

M. Carpinelli
Università di Sassari and INFN, Sassari, Italy
P. Delogu, M. Endrizzi
INFN-Pisa, Pisa, Italy
B. Golosio, P. Oliva
INFN-Cagliari, Monserrato (Cagliari), Italy
I. Pogorelsky, V. Yakimenko
BNL, Upton, Long Island, New York, USA

Inverse Compton scattering (ICS) X-ray sources are of current interest due to their novel features that enable new methods in medical and biological imaging. As a compelling example of such a possibility, we present an experimental demonstration of single shot inline phase contrast imaging using the ICS source located at the BNL Accelerator Test Facility. The phase contrast effect is clearly observed in the images obtained. Further, its qualities are shown to be in agreement with the predictions of theoretical models through comparison of experimental and simulated images of a set of plastic wires of differing composition and size. We also display an example of application of the technique to single shot phase contrast imaging of a biological sample.

WEP133

Adaptive Space-charge Meshing in the General Particle Tracer Code

space-charge, electron, simulation, injection

1728

S.B. van der Geer
Pulsar Physics, Eindhoven, The Netherlands
O.J. Luiten, M.J. de Loos
TUE, Eindhoven, The Netherlands
G. Pöplau, U. van Rienen
Rostock University, Faculty of Computer Science and Electrical Engineering, Rostock, Germany

Efficient and accurate space-charge calculations are essential for the design of high-brightness charged particle sources. Space-charge calculations in the General Particle Tracer (GPT) code make use of an efficient multigrid Poisson solver developed for non-equidistant meshes at Rostock University. GPT uses aggressive mesh-adaptation with highly non-equidistant spacing to speed up calcula- tion time, where the mesh line positions are based upon the projected charge density. Here we present a new meshing scheme where the solution of an intermediate step in the multigrid algorithm is used to define optimal mesh line positions. An analytical test case and comparison with a molecular dynamics calculation of an ultrafast electron diffraction experiment demonstrate the capabilities of this new algorithm in the GPT code.

WEP157

An Implementation of the Fast Multipole Method for High Accuracy Particle Tracking of Intense Beams

multipole, space-charge, simulation, hadron

1782

E.W. Nissen, B. Erdelyi
Northern Illinois University, DeKalb, Illinois, USA

We implement a single level version of the fast multipole method in the software package COSY Infinity. This algorithm has been used in other physics fields to determine high accuracy electrostatic potentials, and is implemented here for charged particle beams. The method scales like NlogN with the particle number and has a priori error estimates, which can be reduced to essentially machine precision if multipole expansions of high enough order are employed, resulting in a highly accurate algorithm for simulation of intense beams without averaging such as encountered in PIC methods. In order to further speed up the algorithm we use COSY Infinity’s innate differential algebraic methods to help with the expansions inherent in this system. Differential algebras allow for fast and exact numerical differentiation of functions that carries through any mathematical transformations performed, and can be used to quickly create the expansions used in the fast multipole method. This can then be combined with moment method techniques to extract transfer maps which include space charge within distributions that are difficult to approximate.

WEP160

Inclusion of Surface Roughness Effects in Emission Modeling With the MICHELLE Code

cathode, electron, space-charge, emittance

1788

J.F. DeFord
STAAR/AWR Corporation, Mequon, USA
N.J. Dionne, S.G. Ovtchinnikov, J.J. Petillo
SAIC, Burlington, Massachusetts, USA

High-brightness electron beams are needed in millimeter-wave tubes and other high-power RF applications. Cathode surface roughness at the micron scale, commonly due to machining or other effects, can lead to broadening of the velocity distribution of electrons downstream, increasing emittance and lowering beam brightness. In this paper we investigate methods of including surface roughness effects in the MICHELLE code*. Modeling of typical surface imperfections over an entire cathode is not feasible, since it requires representation of features that are 3 to 5 orders of magnitude smaller than the cathode. Moreover, the actual surface imperfections for a given cathode are unknown without a prohibitive microscopic investigation of the surface, and these details vary between cathodes with the same machining history. To avoid these problems we investigated modifications to emission models that can account for these effects in an average sense, allowing the use of a smooth emission surface in a model while retaining the essential effects of the rough surface on the beam. We present the results of this investigation, along with representative solutions for sample structures.
*John Petillo, et al., “Recent Developments in the MICHELLE 2D/3D Electron Gun and Collector Modeling Code”, IEEE Trans. Electron Devices Sci., vol. 52, no. 5, May 2005, pp. 742-748.

WEP170

Inspection Camera for Superconducting Cavity at IHEP

cavity, superconducting-cavity, background, focusing

1808

Z.C. Liu, J. Gao, Z.Q. Li
IHEP Beijing, Beijing, People's Republic of China

The first 1.3GHz low-loss large grain 9-cell superconducting cavity for ILC was fabricated at the Institute of High Energy Physics (IHEP) in April, 2010. The gradient of the cavity reached 20MV/m on the first vertical test in KEK in June, 2010. The gradient was limited by quench and field emission of the ninth-cell of the cavity. To locate the position of defects and improve surface processing, we have developed a high resolution inspection camera for the 1.3GHz 9-cell superconducting cavity of IHEP to check the cavity surface and make comparison. The camera is suitable for single and multi-cell 1.3GHz superconducting cavities. As there are several types of cavity under developing in IHEP, the camera was designed to be suitable for different type and frequency cavities like 500MHz BEPC II superconducting cavity, 1.3GHz TESLA and TESLA-like cavity, 1.3GHz and 650MHz low-beta cavity.

WEP281

Beam Imaging of a High-Brightness Elliptic Electron Gun

electron, gun, simulation, focusing

2008

T.M. Bemis, C. Chen, M.H. Lawrence, J.Z. Zhou
Beam Power Technology, Inc., Chelmsford, MA, USA

Funding: This work was funded in part by the Department of Energy, Grant No. DE-FG02-07ER84910.
An innovative research program is being carried out to experimentally demonstrate a high-brightness, space-charge-dominated elliptic electron beam using a non-axisymmetric permanent magnet focusing system. Results of the fabrication, initial testing and beam imaging of an elliptic electron gun are reported. Good agreement is found between the experimental measurements and simulation.

THP007

FEL Potential of eRHIC

FEL, electron, linac, SRF

2151

V. Litvinenko, I. Ben-Zvi, Y. Hao, C.C. Kao, D. Kayran, J.B. Murphy, V. Ptitsyn, T. Roser, D. Trbojevic, N. Tsoupas
BNL, Upton, Long Island, New York, USA

Brookhaven National Laboratory plans to build a 5-to-30 GeV energy-recovery linac (ERL) for its future electron-ion collider, eRHIC. In past few months, the Laboratory turned its attention to the potential of this unique machine for free electron lasers (FELS), which we initially assessed earlier*. In this paper, we present our current vision of a possible FEL farm, and of narrow-band FEL-oscillators driven by this accelerator.
* V.N. Litvinenko, I. Ben-Zvi, Proceedings of FEL'2004, http://jacow.org/f04/papers/WEBOS04/

THP114

Status of the PEP-X Light Source Design Study

emittance, photon, FEL, linac

2336

R.O. Hettel, K.L.F. Bane, K.J. Bertsche, Y. Cai, A. Chao, X. Huang, Y. Jiao, C.-K. Ng, Y. Nosochkov, A. Novokhatski, T. Rabedeau, C.H. Rivetta, J.A. Safranek, G.V. Stupakov, L. Wang, M.-H. Wang, L. Xiao
SLAC, Menlo Park, California, USA

Funding: Work supported in part by Department of Energy Contract DE-AC02-76SF00515 and Office of Basic Energy Sciences, Division of Chemical Sciences.
The SLAC Beam Physics group and collaborators continue to study options for implementing a near diffraction-limited ring-based light source in the 2.2-km PEP-II tunnel that will serve the SSRL scientific program in the future. The study team has completed the baseline design for a 4.5-GeV storage ring having 160-pm-rad emittance with stored beam current of 1.5 A, providing >10²² brightness for multi-keV photon beams from 3.5-m undulator sources. The team is now investigating possible 5-GeV ERL configurations which, similar to the Cornell and KEK ERL plans, would have ~30 pm-rad emittance with 100 mA current, and ~10 pm-rad emittance with 25 mA or less. In the next year, a diffraction-limited storage ring using on-axis injection in order to reach 30 pm-rad or less emittance will be investigated. An overview of the PEP-X design study and SSRL’s plans for defining the performance parameters that will guide the choice of implementation options is presented.

THP120

Light Sources Optimized with Super Bends

dipole, storage-ring, emittance, photon

2342

L. Emery
ANL, Argonne, USA
C. Steier
LBNL, Berkeley, California, USA

Funding: Work at Argonne was supported by U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences, under contract No. DE-AC02-06CH11357
In the past small storage rings with dipole-magnet-only sources were called second-generation light sources (before insertion devices (IDs) were used). With today's technology, e.g. superconducting dipole magnet of 5 T (e.g., ALS's Superbend *), one could make a smaller ring (say, 60-m circumference) with substantial brightness for dipole-magnet beams. Without IDs, these optimized sources would be designated as between second and third generation. Such rings don't exist yet, but their concept can be compared with other types of compact light sources. Typical parameters of such ring would be 60-m circumference, 2 GeV, several 5-T dipole sources in TME-like cells, and 4x10¹³ photons/s/0.1% BW at 1 Angstrom. The number of beamlines is variable, but potentially very large, only limited by funding.
* D. Robin et al., NIM A 538, 1-3, (2005), 65-92.

THP140

Synchrotron Light Options at Super-B

photon, radiation, undulator, synchrotron

2384

W. Wittmer, Y. Nosochkov, A. Novokhatski, J.T. Seeman, M.K. Sullivan
SLAC, Menlo Park, California, USA
M.E. Biagini, P. Raimondi
INFN/LNF, Frascati (Roma), Italy

The Super-B facility will collide electron and positron beams with different characteristics as done in the past at PEP-II and KEKB. The ring and electron (positron) beam characteristic of both high and low energy rings of the Super-B are comparable to NSLS-II and other state of the art synchrotron light sources. This suggests the use of this facility, either parasitically or in dedicated runs, as light source. In this paper we compare the characteristics of the synchrotron light generated at Super-B with existing, in construction and proposed facilities. We investigate different schemes to incorporate the generation of synchrotron radiation in the collider lattice design and look at different beam line layouts for users.

FROAN3

High-Intensity, High-Brightness Polarized and Unpolarized Beam Production in Charge- Exchange Collisions

ion, proton, polarization, solenoid

2555

A. Zelenski, G. Atoian, J. Ritter, D. Steski, V. Zubets
BNL, Upton, Long Island, New York, USA
V.I. Davydenko, A.V. Ivanov, V.V. Kolmogorov
BINP SB RAS, Novosibirsk, Russia

Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy.
Basic limitations on the high-intensity H⁻ ion beam production were experimentally studied in charge-exchange collisions of the neutral atomic hydrogen beam in the Na- vapor jet ionizer cell. These studies are the part of the polarized source upgrade (to 10 mA peak current and 85% polarization) project for RHIC. In the source the atomic hydrogen beam of a 3-5 keV energy and total (equivalent) current up to 5 A is produced by neutralization of proton beam in pulsed hydrogen gas target. Formation of the proton beam (from the surface of the plasma emitter with a low transverse ion temperature ~0.2 eV) is produced by four-electrode spherical multi-aperture ion-optical system with geometrical focusing. The hydrogen atomic beam intensity up to 1.0 A /cm² (equivalent) was obtained in the Na-jet ionizer aperture of a 2.0 cm diameter. At the first stage of the experiment H⁻ beam with 36 mA current, 5 keV energy and ~1.0 cm-mrad normalized emittance was obtained using the flat grids and magnetic focusing. The experimental results of the high-intensity neutral hydrogen beam generation and studies of the charge-exchange polarization processes of this intense beam will be presented.

Slides FROAN3 [6.093 MB]