ICAP2012 - List of Keywords (gun)

Paper	Title	Other Keywords	Page
MOSDI1	Analyzing Multipacting Problems in Accelerators using ACE3P on High Performance Computers	cavity, simulation, electron, SRF	54
	L. Ge, C. Ko, K.H. Lee, Z. Li, C.-K. Ng, L. Xiao SLAC, Menlo Park, California, USA
	Funding: This material is based upon work supported by the U.S. Department of Energy Office of Science under Cooperative Agreement DE-SC0000661 Track3P is the particle tracking module of ACE3P, a 3D parallel finite element electromagnetic code suite developed at SLAC which has been implemented on the US DOE supercomputers at NERSC to simulate large-scale complex accelerator designs. Using the higher-order cavity fields generated by ACE3P codes, Track3P has been used for analyzing multipacting (MP) in accelerator cavities. The prediction of the MP barriers in the ICHIRO cavity at KEK was the first Track3P benchmark against measurements. Using a large number of processors, Track3P can scan through the field gradient and cavity surface efficiently, and its comprehensive postprocessing tool allows the identifications of both the hard and soft MP barriers and the locations of MP activities. Results from applications of this high performance simulation capability to accelerators such as the Quarter Wave Resonator for FRIB, the 704 MHz SRF gun cavity for BNL ERL and the Muon cooling cavity for Muon Collider will be presented.

WEP08	Comparison of Different Electromagnetic Solvers for Accelerator Simulations	simulation, wakefield	155
	J. Xu, R. Zhao, X. Zhufu IS, Beijing, People's Republic of China C. Li, X. Qi, L. Yang IMP, Lanzhou, People's Republic of China M. Min ANL, Argonne, USA
	Funding: Chinese Academy of Science Electromagnetic simulations are fundamental for accelerator modeling. In this paper two high-order numerical methods will be studied. These include continuous Galerkin (CG) method with vector bases, and discontinuous Galerkin (DG) method with nodal bases. Both methods apply domain decomposition method for the parallelization. Due to the difference in the numerical methods, these methods have different performance in speed and accuracy. DG method on unstructured grid has the advantages of easy parallelization, good scalability, and strong capability to handle complex geometries. Benchmarks of these methods will be shown on simple geometries in detail first. Then they will be applied for simulation in accelerator devices, and the results will be compared and discussed.

THAAI1	The Dark Current and Multipacting Capabilities in OPAL: Model, Benchmarks and Applications	electron, simulation, cyclotron, cavity	201
	C. Wang, Z.G. Yin, T.J. Zhang CIAE, Beijing, People's Republic of China A. Adelmann PSI, Villigen, Switzerland
	Dark current and multiple electron impacts (multipacting), as for example observed in radio frequency (RF) structures of accelerators, are usually harmful to the equipment and the beam quality. These effects need to be suppressed to guarantee stable operation. Large scale simulations can be used to understand the cause and develop strategies to suppress these phenomena. We extend OPAL, a parallel framework for charged particle optics in accelerator structures and beam lines, with the necessary physics models to efficiently and precise simulate multipacting phenomenas. We added a Fowler-Nordheim field emission model, two secondary electron emission models, developed by Furman-Pivi and Vaughan respectively, as well as efficient 3D boundary geometry handling capabilities. The models and their implementation are carefully benchmark against a non-stationary multipacting theory for the classic parallel plate geometry. A dedicated, parallel plate experiment shows excellent agreement between theory, model/simulations and experiment.
	Slides THAAI1 [6.191 MB]

THP13	Emission Studies of Photocathode RF Gun at PITZ	electron, cathode, simulation, space-charge	242
	J. Li, G. Asova, M. Groß, L. Hakobyan, I.I. Isaev, Ye. Ivanisenko, M. Khojoyan, G. Klemz, G. Kourkafas, M. Krasilnikov, K. Kusoljariyakul, M. Mahgoub, D. Malyutin, B. Marchetti, A. Oppelt, B. Petrosyan, S. Rimjaem, A. Shapovalov, F. Stephan, G. Vashchenko DESY Zeuthen, Zeuthen, Germany G. Feng DESY, Hamburg, Germany D. Richter HZB, Berlin, Germany L. Shang USTC/NSRL, Hefei, Anhui, People's Republic of China
	The Photo Injector Test facility at DESY, Zeuthen site (PITZ), was built to develop and optimize electron sources for linac based Free Electron Lasers(FELs) like FLASH and the European XFEL. For the value of the bunch charge extracted from a photocathode, discrepancy has been observed between the data measured at PITZ and simulation results from the ASTRA code. As a factor which could explain the discrepancy, a Schottky-like effect is considered. Meanwhile, the Parmela code was applied to the emission studies on the PITZ gun as benchmark. Since Parmela cannot be used to simulate a Schottky-like effect with its own modules, MATLAB scripts have been developed to implement this feature of the photoemission in an RF gun.

FRAAC4	Astra based Swarm Optimizations of the BERLinPro Injector	emittance, linac, cavity, booster	281
	M. Abo-Bakr, B.C. Kuske HZB, Berlin, Germany
	The Berlin Energy Recovery Linac Project BERLinPro is a compact ERL to develop the accelerator physics and technology required to generate and accelerate a 100-mA, 1-mm mrad normalized emittance beam. One of the project challenges is to generate a beam of this kind in the injector part of the machine. Extensive injector optimization studies have been done over the last years. A deep insight in the physics of high brilliance, low energy beams together with single parameter scans allowed for an efficient optimization, resulting in a layout, capable to deliver bunches of the needed charge and dimension. However, changes in the injector components' technical layout, as they are unavoidable in the current stage of the project, may require re-optimizations at any time, if necessary of the whole injector part. To support these work an ASTRA based 'swarm optimization' tool for massive parallel calculations on the institutes Linux computing cluster has been developed. Once the optimization wrapper code is written, results come for free and can help to extend the understanding of the underlying physics. Strategy, procedure and results of the 'swarm optimizations' will be presented in this paper.
	Slides FRAAC4 [7.286 MB]

Paper

Title

Other Keywords

Page

MOSDI1

Analyzing Multipacting Problems in Accelerators using ACE3P on High Performance Computers

cavity, simulation, electron, SRF

54

L. Ge, C. Ko, K.H. Lee, Z. Li, C.-K. Ng, L. Xiao
SLAC, Menlo Park, California, USA

Funding: This material is based upon work supported by the U.S. Department of Energy Office of Science under Cooperative Agreement DE-SC0000661
Track3P is the particle tracking module of ACE3P, a 3D parallel finite element electromagnetic code suite developed at SLAC which has been implemented on the US DOE supercomputers at NERSC to simulate large-scale complex accelerator designs. Using the higher-order cavity fields generated by ACE3P codes, Track3P has been used for analyzing multipacting (MP) in accelerator cavities. The prediction of the MP barriers in the ICHIRO cavity at KEK was the first Track3P benchmark against measurements. Using a large number of processors, Track3P can scan through the field gradient and cavity surface efficiently, and its comprehensive postprocessing tool allows the identifications of both the hard and soft MP barriers and the locations of MP activities. Results from applications of this high performance simulation capability to accelerators such as the Quarter Wave Resonator for FRIB, the 704 MHz SRF gun cavity for BNL ERL and the Muon cooling cavity for Muon Collider will be presented.

WEP08

Comparison of Different Electromagnetic Solvers for Accelerator Simulations

simulation, wakefield

155

J. Xu, R. Zhao, X. Zhufu
IS, Beijing, People's Republic of China
C. Li, X. Qi, L. Yang
IMP, Lanzhou, People's Republic of China
M. Min
ANL, Argonne, USA

Funding: Chinese Academy of Science
Electromagnetic simulations are fundamental for accelerator modeling. In this paper two high-order numerical methods will be studied. These include continuous Galerkin (CG) method with vector bases, and discontinuous Galerkin (DG) method with nodal bases. Both methods apply domain decomposition method for the parallelization. Due to the difference in the numerical methods, these methods have different performance in speed and accuracy. DG method on unstructured grid has the advantages of easy parallelization, good scalability, and strong capability to handle complex geometries. Benchmarks of these methods will be shown on simple geometries in detail first. Then they will be applied for simulation in accelerator devices, and the results will be compared and discussed.

THAAI1

The Dark Current and Multipacting Capabilities in OPAL: Model, Benchmarks and Applications

electron, simulation, cyclotron, cavity

201

C. Wang, Z.G. Yin, T.J. Zhang
CIAE, Beijing, People's Republic of China
A. Adelmann
PSI, Villigen, Switzerland

Dark current and multiple electron impacts (multipacting), as for example observed in radio frequency (RF) structures of accelerators, are usually harmful to the equipment and the beam quality. These effects need to be suppressed to guarantee stable operation. Large scale simulations can be used to understand the cause and develop strategies to suppress these phenomena. We extend OPAL, a parallel framework for charged particle optics in accelerator structures and beam lines, with the necessary physics models to efficiently and precise simulate multipacting phenomenas. We added a Fowler-Nordheim field emission model, two secondary electron emission models, developed by Furman-Pivi and Vaughan respectively, as well as efficient 3D boundary geometry handling capabilities. The models and their implementation are carefully benchmark against a non-stationary multipacting theory for the classic parallel plate geometry. A dedicated, parallel plate experiment shows excellent agreement between theory, model/simulations and experiment.

Slides THAAI1 [6.191 MB]

THP13

Emission Studies of Photocathode RF Gun at PITZ

electron, cathode, simulation, space-charge

242

J. Li, G. Asova, M. Groß, L. Hakobyan, I.I. Isaev, Ye. Ivanisenko, M. Khojoyan, G. Klemz, G. Kourkafas, M. Krasilnikov, K. Kusoljariyakul, M. Mahgoub, D. Malyutin, B. Marchetti, A. Oppelt, B. Petrosyan, S. Rimjaem, A. Shapovalov, F. Stephan, G. Vashchenko
DESY Zeuthen, Zeuthen, Germany
G. Feng
DESY, Hamburg, Germany
D. Richter
HZB, Berlin, Germany
L. Shang
USTC/NSRL, Hefei, Anhui, People's Republic of China

The Photo Injector Test facility at DESY, Zeuthen site (PITZ), was built to develop and optimize electron sources for linac based Free Electron Lasers(FELs) like FLASH and the European XFEL. For the value of the bunch charge extracted from a photocathode, discrepancy has been observed between the data measured at PITZ and simulation results from the ASTRA code. As a factor which could explain the discrepancy, a Schottky-like effect is considered. Meanwhile, the Parmela code was applied to the emission studies on the PITZ gun as benchmark. Since Parmela cannot be used to simulate a Schottky-like effect with its own modules, MATLAB scripts have been developed to implement this feature of the photoemission in an RF gun.

FRAAC4

Astra based Swarm Optimizations of the BERLinPro Injector

emittance, linac, cavity, booster

281

M. Abo-Bakr, B.C. Kuske
HZB, Berlin, Germany

The Berlin Energy Recovery Linac Project BERLinPro is a compact ERL to develop the accelerator physics and technology required to generate and accelerate a 100-mA, 1-mm mrad normalized emittance beam. One of the project challenges is to generate a beam of this kind in the injector part of the machine. Extensive injector optimization studies have been done over the last years. A deep insight in the physics of high brilliance, low energy beams together with single parameter scans allowed for an efficient optimization, resulting in a layout, capable to deliver bunches of the needed charge and dimension. However, changes in the injector components' technical layout, as they are unavoidable in the current stage of the project, may require re-optimizations at any time, if necessary of the whole injector part. To support these work an ASTRA based 'swarm optimization' tool for massive parallel calculations on the institutes Linux computing cluster has been developed. Once the optimization wrapper code is written, results come for free and can help to extend the understanding of the underlying physics. Strategy, procedure and results of the 'swarm optimizations' will be presented in this paper.

Slides FRAAC4 [7.286 MB]