ICAP2012 - List of Keywords (laser)

Paper	Title	Other Keywords	Page
TUABC3	Multi-Objective Genetic Optimization of Linac Beam Parameters for a seeded FEL	linac, FEL, electron, simulation	75
	M. Apollonio, R. Bartolini, I.P.S. Martin Diamond, Oxfordshire, United Kingdom
	The optimization of the beam dynamics in a Linac for free electron lasers (FELs) can be a very time consuming process, in which several parameters of the acceleration and compression sections need to be varied simultaneously. The optimization procedure is required to tackle different and often opposite goals at a time, depending on the adopted FEL scheme. As such, multi-objective genetic algorithms are an interesting choice, given their ability to targeting several, often conflicting objectives. We have studied an optimization strategy based on a combination of multi-objective optimization with a fast parallel computation of the FEL performance and, for the specific case of the proposed UK’s New Light Source, we illustrate the benefits of this method for the optimization of the average gain length and its variation along the beam pulse. The method can be extended to other sets of objectives, such as power and bandwidth of the FEL.
	Slides TUABC3 [5.567 MB]

TUSBC2	Low Noise Particle-in-Cell Simulations of Laser Plasma Accelerator 10 GeV Stages	plasma, simulation, emittance, electron	78
	E. Cormier-Michel, D.L. Bruhwiler, J.R. Cary, B.M. Cowan, E.J. Hallman Tech-X, Boulder, Colorado, USA E. Esarey, C.G.R. Geddes, W. Leemans, C.B. Schroeder, J.-L. Vay LBNL, Berkeley, California, USA
	Funding: Work supported by DOE/HEP, under grants DE-SC0004441 and DE-FC02-07ER41499, including use of NERSC under DE-AC02-05CH11231. Because of their ultra-high accelerating gradient, laser plasma based accelerators (LPA) are contemplated for the next generation of high-energy colliders and light sources. The upcoming BELLA project will explore acceleration of electron bunches to 10 GeV in a 1 meter long plasma, where a wakefield is driven by a PW-class laser. Particle-in-cell (PIC) simulations are used to design the upcoming experiments where boosted frame simulations are used to model the full scale stages. As criteria on energy spread and beam emittance become more stringent, PIC simulations become more challenging as high frequency noise artificially increases those quantities. We show that calculating the beam self-fields using a static Poisson solve in the beam frame dramatically reduces particle noise, allowing for more accurate simulation of the beam evolution. In particular, this method gets correct cancellation of the transverse self-electric and magnetic fields of the beam, eliminating artificial self-forces, which is usually not true when using the standard PIC algorithm based on the staggered (“Yee”) electromagnetic field solver.
	Slides TUSBC2 [5.989 MB]

WEACC2	Space Charge Effects and Focusing Methods for Laser Accelerated Ion Beams	space-charge, solenoid, simulation, focusing	184
	P. Schmidt, O. Boine-Frankenheim, V. Kornilov, P. Spädtke GSI, Darmstadt, Germany
	Funding: GSI Helmholtzzentrum für Schwerionenforschung Planckstr. 1 D-64291 Darmstadt We employ the 3D PIC simulation code VORPAL to study the transport of laser accelerated proton beams in the framework of the LIGHT project at GSI. Initially the beam is assumed to be neutralized by co-moving electrons. For different initial beam distribution models we study the effect of space charge after the electrons have been removed. The results of the simulations are compared to an envelope model. We derive conditions in terms of the beam parameters and the distance from the production target for a safe removal of the electrons. As an option for the controlled de-neutralization of the beam a thin metallic foil is studied. Besides space charge, we also account for the effect of secondary electrons generated from the foil.
	Slides WEACC2 [0.993 MB]

THAAI2	Efficient Modeling of Laser-plasma Accelerators Using the Ponderomotive-based Code INF&RNO	simulation, plasma, wakefield, electron	206
	C. Benedetti, E. Esarey, W. Leemans, C.B. Schroeder LBNL, Berkeley, California, USA
	Funding: Work supported by the Office of Science, Office of High Energy Physics, of the U.S. Department of Energy under Contract No. DE-AC02-05CH11231. Numerical modeling of laser-plasma accelerators using the ponderomotive approximation allows efficient modeling of 10 GeV and beyond laser-plasma accelerators. The time-averaged ponderomotive force approximation also allows simulation in cylindrical geometry which captures relevant 3D physics at 2D computational cost. In this talk I will present the code INF&RNO (INtegrated Fluid & paRticle simulatioN cOde). The code is based on an envelope model for the laser while either a PIC or a fluid description can be used for the plasma. The effect of the laser pulse on the plasma is modeled with the time-averaged poderomotive force. These and other features, such as dynamical resampling of the phase space distribution to reduce on-axis noise and boosted-Lorentz-frame modeling capability, allow for a speedup of several orders of magnitude compared to standard full PIC simulations while still retaining physical fidelity. The code has been benchmarked against analytical solutions and 3D PIC simulations and a set of validation tests together with a discussion of the performances will be presented. Applications to the BELLA PW laser-plasma accelerator experiments at LBNL will be discussed.
	Slides THAAI2 [1.881 MB]

THP07	Some Computational Challenges in the Modeling of Accelerators and their Solutions in the Simulation Code Warp	plasma, simulation, acceleration, electron	233
	J.-L. Vay, C. Benedetti LBNL, Berkeley, California, USA R.H. Cohen, A. Friedman, D.P. Grote LLNL, Livermore, California, USA
	Funding: Supported by US-DOE Contracts DE-AC02-05CH11231 and DE-AC52-07NA27344, and the SciDAC/ComPASS project. Used resources of NERSC, supported by US-DOE Contract DE-AC02-05CH11231. The Particle-In-Cell Code-Framework Warp originated in the Heavy Ion Fusion program to guide the development of accelerators that can deliver beams suitable for implosion of inertial fusion capsules. The range of application of Warp has considerably widened far beyond the initial area and it is now applied to the study and design of existing and next-generation high-energy accelerators, including, for example, the study of laser wakefield acceleration and electron cloud effects. We present an overview of Warp's capabilities, summarizing recent original numerical methods that were developed to address computational challenges such as space and time scale disparities, spurious numerical dispersion, efficient wideband digital filtering on parallel platforms, etc. The original methods include simulations in Lorentz boosted frames, an electromagnetic solver with tunable numerical dispersion and efficient stride-based digital filtering, Particle-In-Cell with Adaptive Mesh Refinement, a large-timestep ‘‘drift-Lorentz'' mover for arbitrarily magnetized species, and a relativistic Lorentz invariant leapfrog particle pusher. Selected examples of applications will be given.

THP08	Beam Dynamics Studies for Particle Driven Plasma Wakefield Acceleration Experiments at PITZ	plasma, electron, simulation, focusing	236
	M. Khojoyan, M. Groß, G. Klemz, G. Koss, M. Krasilnikov, A. Oppelt, F. Stephan DESY Zeuthen, Zeuthen, Germany M. Khojoyan ANSL, Yerevan, Armenia
	The Photo Injector Test Facility at DESY, Zeuthen site (PITZ) is developing and optimizing high brightness electron sources for linac based free electron lasers such as FLASH and the European XFEL. The high quality of the 25 MeV electron beam together with the availability of a highly flexible photocathode laser system makes the PITZ injector a perfect facility for variety of experimental studies. Two approaches are of great interest for future applications in the context of particle driven plasma wakefield acceleration experiments: self-modulation and transformer ratio studies. In both cases a high density electron beam is interacting with a plasma which has a density of about 10¹⁵ cm^-3. ASTRA simulations were done to study the e-beam density along the existing PITZ beamline, especially at two different possible longitudinal positions of the planned plasma cell, in order to reach the particle density required for occurrence of self-modulation. The results of the beam dynamics studies are presented and discussed in this paper.

THACC3	Preliminary Study of Single Spike SASE FEL Operation at 0.26 Nanometers Wavelength for the European XFEL	electron, radiation, simulation, FEL	253
	B. Marchetti, M. Krasilnikov, F. Stephan DESY Zeuthen, Zeuthen, Germany M. Dohlus, Y.A. Kot, I. Zagorodnov DESY, Hamburg, Germany J. Rönsch-Schulenburg Uni HH, Hamburg, Germany
	The production of ultra-short (fs or sub-fs long), high power, radiation pulses in the X-ray spectral region, showing a single spike spectrum, represents a challenge for many existent SASE- FELs [1, 2]. In order to realize single spike operation the length of the electron bunch after compression must be extremely small [3] (less than a micrometer) and the consequent degradation of its emittance has not to suppress the radiation production. Several technical restrictions, such as limits of diagnostics for small charges, RF jitter and micro-bunching instabilities play an important role in the choice of the operation working point. In this paper we are going to study the feasibility of single spike or few spikes lasing for bunches with charge of tens of pC in the European XFEL facility giving some preliminary results concerning the choice of the working point. [1] J.B. Rosenzweig et al., NIM A 593 (2008) 39-44 [2] S. Reiche et al., NIM A 593 (2008) 45-48 [3] R. Bonifacio et al., PRL vol. 73 n.1 (1994)
	Slides THACC3 [1.401 MB]

FRSAI3	PIC Simulations of Laser Ion Acceleration via TNSA	simulation, electron, proton, plasma	290
	L. Lecz TEMF, TU Darmstadt, Darmstadt, Germany O. Boine-Frankenheim, V. Kornilov GSI, Darmstadt, Germany
	The laser acceleration of protons via the TNSA (Target Normal Sheath Acceleration) mechanism from a thin metal foil (few micrometer) interacting with intense and short (several 100 fs) laser pulse is investigated by using 1D and 2D particle-in-cell electro-magnetic VORPAL [1] simulations. The protons originate from the very thin hydrogen-rich contamination layer on the target rear surface. In the 1D view we have found that two models well describe the longitudinal acceleration in the two extreme cases: quasi-static acceleration [2] for mono-layers and isothermal plasma expansion [3] for thick layers. The grid heating, which is the most important issue in 2D simulations, and its effect on the proton acceleration is discussed. The required numerical parameters and boundary conditions for stable and reliable 2D simulations are also presented. [1] http://www.txcorp.com/products/VORPAL/ [2] M. Passoni et al., Phys Rev E 69, 026411 (2004) [3] P. Mora, Phys. Rev. Lett., 90, 185002 (2003)
	Slides FRSAI3 [4.325 MB]

FRABI2	Big Data Analysis and Visualization: What Do Linacs and Tropical Cyclones Have in Common?	simulation, plasma, linac, electron	299
	E.W. Bethel, S. Byna, J. Chou, E. Cormier-Michel, C.G.R. Geddes, M. Howison, F. Li, P. Prabhat, J. Qiang, O. Rübel, R.D. Ryne, M.F. Wehner, K. Wu LBNL, Berkeley, California, USA
	Funding: This work was supported by the Director, Office of Science, Office and Advanced Scientific Computing Research, of the U.S. Department of Energy under Contract No. DE-AC02-05CH11231. While there is wisdom in the old adage "the two constants in life are death and taxes," there are unavoidable truths facing modern experimental and computational science. First is the growing "impedence mismatch" between our ability to collect and generate data, and our ability to store, manage, and gain understanding from it. The second is the fact that we cannot continue to rely on the same software technologies that have worked well for the past couple of decades for data management, analysis, and visualization. A third is that these complementary activities must be considered in a holistic, rather than balkanized way. The inseperable interplay between data management, analysis, visualization, and high performance computational infrastructure, are best viewed through the lens of case studies from multiple scientific domains, where teams of computer and accelerator scientists combine forces to tackle challenging data understanding problems.
	Slides FRABI2 [3.622 MB]

Paper

Title

Other Keywords

Page

TUABC3

Multi-Objective Genetic Optimization of Linac Beam Parameters for a seeded FEL

linac, FEL, electron, simulation

75

M. Apollonio, R. Bartolini, I.P.S. Martin
Diamond, Oxfordshire, United Kingdom

The optimization of the beam dynamics in a Linac for free electron lasers (FELs) can be a very time consuming process, in which several parameters of the acceleration and compression sections need to be varied simultaneously. The optimization procedure is required to tackle different and often opposite goals at a time, depending on the adopted FEL scheme. As such, multi-objective genetic algorithms are an interesting choice, given their ability to targeting several, often conflicting objectives. We have studied an optimization strategy based on a combination of multi-objective optimization with a fast parallel computation of the FEL performance and, for the specific case of the proposed UK’s New Light Source, we illustrate the benefits of this method for the optimization of the average gain length and its variation along the beam pulse. The method can be extended to other sets of objectives, such as power and bandwidth of the FEL.

Slides TUABC3 [5.567 MB]

TUSBC2

Low Noise Particle-in-Cell Simulations of Laser Plasma Accelerator 10 GeV Stages

plasma, simulation, emittance, electron

78

E. Cormier-Michel, D.L. Bruhwiler, J.R. Cary, B.M. Cowan, E.J. Hallman
Tech-X, Boulder, Colorado, USA
E. Esarey, C.G.R. Geddes, W. Leemans, C.B. Schroeder, J.-L. Vay
LBNL, Berkeley, California, USA

Funding: Work supported by DOE/HEP, under grants DE-SC0004441 and DE-FC02-07ER41499, including use of NERSC under DE-AC02-05CH11231.
Because of their ultra-high accelerating gradient, laser plasma based accelerators (LPA) are contemplated for the next generation of high-energy colliders and light sources. The upcoming BELLA project will explore acceleration of electron bunches to 10 GeV in a 1 meter long plasma, where a wakefield is driven by a PW-class laser. Particle-in-cell (PIC) simulations are used to design the upcoming experiments where boosted frame simulations are used to model the full scale stages. As criteria on energy spread and beam emittance become more stringent, PIC simulations become more challenging as high frequency noise artificially increases those quantities. We show that calculating the beam self-fields using a static Poisson solve in the beam frame dramatically reduces particle noise, allowing for more accurate simulation of the beam evolution. In particular, this method gets correct cancellation of the transverse self-electric and magnetic fields of the beam, eliminating artificial self-forces, which is usually not true when using the standard PIC algorithm based on the staggered (“Yee”) electromagnetic field solver.

Slides TUSBC2 [5.989 MB]

WEACC2

Space Charge Effects and Focusing Methods for Laser Accelerated Ion Beams

space-charge, solenoid, simulation, focusing

184

P. Schmidt, O. Boine-Frankenheim, V. Kornilov, P. Spädtke
GSI, Darmstadt, Germany

Funding: GSI Helmholtzzentrum für Schwerionenforschung Planckstr. 1 D-64291 Darmstadt
We employ the 3D PIC simulation code VORPAL to study the transport of laser accelerated proton beams in the framework of the LIGHT project at GSI. Initially the beam is assumed to be neutralized by co-moving electrons. For different initial beam distribution models we study the effect of space charge after the electrons have been removed. The results of the simulations are compared to an envelope model. We derive conditions in terms of the beam parameters and the distance from the production target for a safe removal of the electrons. As an option for the controlled de-neutralization of the beam a thin metallic foil is studied. Besides space charge, we also account for the effect of secondary electrons generated from the foil.

Slides WEACC2 [0.993 MB]

THAAI2

Efficient Modeling of Laser-plasma Accelerators Using the Ponderomotive-based Code INF&RNO

simulation, plasma, wakefield, electron

206

C. Benedetti, E. Esarey, W. Leemans, C.B. Schroeder
LBNL, Berkeley, California, USA

Funding: Work supported by the Office of Science, Office of High Energy Physics, of the U.S. Department of Energy under Contract No. DE-AC02-05CH11231.
Numerical modeling of laser-plasma accelerators using the ponderomotive approximation allows efficient modeling of 10 GeV and beyond laser-plasma accelerators. The time-averaged ponderomotive force approximation also allows simulation in cylindrical geometry which captures relevant 3D physics at 2D computational cost. In this talk I will present the code INF&RNO (INtegrated Fluid & paRticle simulatioN cOde). The code is based on an envelope model for the laser while either a PIC or a fluid description can be used for the plasma. The effect of the laser pulse on the plasma is modeled with the time-averaged poderomotive force. These and other features, such as dynamical resampling of the phase space distribution to reduce on-axis noise and boosted-Lorentz-frame modeling capability, allow for a speedup of several orders of magnitude compared to standard full PIC simulations while still retaining physical fidelity. The code has been benchmarked against analytical solutions and 3D PIC simulations and a set of validation tests together with a discussion of the performances will be presented. Applications to the BELLA PW laser-plasma accelerator experiments at LBNL will be discussed.

Slides THAAI2 [1.881 MB]

THP07

Some Computational Challenges in the Modeling of Accelerators and their Solutions in the Simulation Code Warp

plasma, simulation, acceleration, electron

233

J.-L. Vay, C. Benedetti
LBNL, Berkeley, California, USA
R.H. Cohen, A. Friedman, D.P. Grote
LLNL, Livermore, California, USA

Funding: Supported by US-DOE Contracts DE-AC02-05CH11231 and DE-AC52-07NA27344, and the SciDAC/ComPASS project. Used resources of NERSC, supported by US-DOE Contract DE-AC02-05CH11231.
The Particle-In-Cell Code-Framework Warp originated in the Heavy Ion Fusion program to guide the development of accelerators that can deliver beams suitable for implosion of inertial fusion capsules. The range of application of Warp has considerably widened far beyond the initial area and it is now applied to the study and design of existing and next-generation high-energy accelerators, including, for example, the study of laser wakefield acceleration and electron cloud effects. We present an overview of Warp's capabilities, summarizing recent original numerical methods that were developed to address computational challenges such as space and time scale disparities, spurious numerical dispersion, efficient wideband digital filtering on parallel platforms, etc. The original methods include simulations in Lorentz boosted frames, an electromagnetic solver with tunable numerical dispersion and efficient stride-based digital filtering, Particle-In-Cell with Adaptive Mesh Refinement, a large-timestep ‘‘drift-Lorentz'' mover for arbitrarily magnetized species, and a relativistic Lorentz invariant leapfrog particle pusher. Selected examples of applications will be given.

THP08

Beam Dynamics Studies for Particle Driven Plasma Wakefield Acceleration Experiments at PITZ

plasma, electron, simulation, focusing

236

M. Khojoyan, M. Groß, G. Klemz, G. Koss, M. Krasilnikov, A. Oppelt, F. Stephan
DESY Zeuthen, Zeuthen, Germany
M. Khojoyan
ANSL, Yerevan, Armenia

The Photo Injector Test Facility at DESY, Zeuthen site (PITZ) is developing and optimizing high brightness electron sources for linac based free electron lasers such as FLASH and the European XFEL. The high quality of the 25 MeV electron beam together with the availability of a highly flexible photocathode laser system makes the PITZ injector a perfect facility for variety of experimental studies. Two approaches are of great interest for future applications in the context of particle driven plasma wakefield acceleration experiments: self-modulation and transformer ratio studies. In both cases a high density electron beam is interacting with a plasma which has a density of about 10¹⁵ cm^-3. ASTRA simulations were done to study the e-beam density along the existing PITZ beamline, especially at two different possible longitudinal positions of the planned plasma cell, in order to reach the particle density required for occurrence of self-modulation. The results of the beam dynamics studies are presented and discussed in this paper.

THACC3

Preliminary Study of Single Spike SASE FEL Operation at 0.26 Nanometers Wavelength for the European XFEL

electron, radiation, simulation, FEL

253

B. Marchetti, M. Krasilnikov, F. Stephan
DESY Zeuthen, Zeuthen, Germany
M. Dohlus, Y.A. Kot, I. Zagorodnov
DESY, Hamburg, Germany
J. Rönsch-Schulenburg
Uni HH, Hamburg, Germany

The production of ultra-short (fs or sub-fs long), high power, radiation pulses in the X-ray spectral region, showing a single spike spectrum, represents a challenge for many existent SASE- FELs [1, 2]. In order to realize single spike operation the length of the electron bunch after compression must be extremely small [3] (less than a micrometer) and the consequent degradation of its emittance has not to suppress the radiation production. Several technical restrictions, such as limits of diagnostics for small charges, RF jitter and micro-bunching instabilities play an important role in the choice of the operation working point. In this paper we are going to study the feasibility of single spike or few spikes lasing for bunches with charge of tens of pC in the European XFEL facility giving some preliminary results concerning the choice of the working point.
[1] J.B. Rosenzweig et al., NIM A 593 (2008) 39-44
[2] S. Reiche et al., NIM A 593 (2008) 45-48
[3] R. Bonifacio et al., PRL vol. 73 n.1 (1994)

Slides THACC3 [1.401 MB]

FRSAI3

PIC Simulations of Laser Ion Acceleration via TNSA

simulation, electron, proton, plasma

290

L. Lecz
TEMF, TU Darmstadt, Darmstadt, Germany
O. Boine-Frankenheim, V. Kornilov
GSI, Darmstadt, Germany

The laser acceleration of protons via the TNSA (Target Normal Sheath Acceleration) mechanism from a thin metal foil (few micrometer) interacting with intense and short (several 100 fs) laser pulse is investigated by using 1D and 2D particle-in-cell electro-magnetic VORPAL [1] simulations. The protons originate from the very thin hydrogen-rich contamination layer on the target rear surface. In the 1D view we have found that two models well describe the longitudinal acceleration in the two extreme cases: quasi-static acceleration [2] for mono-layers and isothermal plasma expansion [3] for thick layers. The grid heating, which is the most important issue in 2D simulations, and its effect on the proton acceleration is discussed. The required numerical parameters and boundary conditions for stable and reliable 2D simulations are also presented.
[1] http://www.txcorp.com/products/VORPAL/
[2] M. Passoni et al., Phys Rev E 69, 026411 (2004)
[3] P. Mora, Phys. Rev. Lett., 90, 185002 (2003)

Slides FRSAI3 [4.325 MB]

FRABI2

Big Data Analysis and Visualization: What Do Linacs and Tropical Cyclones Have in Common?

simulation, plasma, linac, electron

299

E.W. Bethel, S. Byna, J. Chou, E. Cormier-Michel, C.G.R. Geddes, M. Howison, F. Li, P. Prabhat, J. Qiang, O. Rübel, R.D. Ryne, M.F. Wehner, K. Wu
LBNL, Berkeley, California, USA

Funding: This work was supported by the Director, Office of Science, Office and Advanced Scientific Computing Research, of the U.S. Department of Energy under Contract No. DE-AC02-05CH11231.
While there is wisdom in the old adage "the two constants in life are death and taxes," there are unavoidable truths facing modern experimental and computational science. First is the growing "impedence mismatch" between our ability to collect and generate data, and our ability to store, manage, and gain understanding from it. The second is the fact that we cannot continue to rely on the same software technologies that have worked well for the past couple of decades for data management, analysis, and visualization. A third is that these complementary activities must be considered in a holistic, rather than balkanized way. The inseperable interplay between data management, analysis, visualization, and high performance computational infrastructure, are best viewed through the lens of case studies from multiple scientific domains, where teams of computer and accelerator scientists combine forces to tackle challenging data understanding problems.

Slides FRABI2 [3.622 MB]