ICAP2018 - List of Keywords (plasma)

Paper	Title	Other Keywords	Page
SUPAF04	Symplectic and Self-Consistent Algorithms for Particle Accelerator Simulation	simulation, space-charge, betatron, resonance	42
	T. Planche, P. M. Jung TRIUMF, Vancouver, Canada
	This paper is a review of algorithms, applicable to particle accelerator simulation, which share the following two characteristics: (1) they preserve to machine precision the symplectic geometry of the particle dynamics, and (2) they track the evolution of the self-field consistently with the evolution of the charge distribution. This review includes, but is not limited to, algorithms using a Particle-in-Cell discretization scheme. At the end of this review we discuss to possibility to derived algorithms from an electrostatic Hamiltonian.
	Slides SUPAF04 [0.424 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-ICAP2018-SUPAF04
About •	paper received ※ 19 October 2018 paper accepted ※ 24 October 2018 issue date ※ 26 January 2019
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

SUPAF05	Polarized Proton Beams From Laser-Induced Plasmas	laser, proton, polarization, target	46
	M. Büscher, J. Böker, R. Engels, I. Engin, R. Gebel, A. Hützen, A. Lehrach FZJ, Jülich, Germany A.M. Pukhov, J. Thomas HHUD, Dusseldorf, Germany T. P. Rakitzis, D. Sofikitis University of Crete, Heraklion, Crete, Greece
	Laser-driven particle acceleration has undergone impressive progress in recent years. Nevertheless, one unexplored issue is how the particle spins are influenced by the huge magnetic fields inherently present in the plasmas. In the framework of the JuSPARC (Jülich Short-Pulse Particle and Radiation Center) facility and of the ATHENA consortium, the laser-driven generation of polarized particle beams in combination with the development of advanced target technologies is being pursued. In order to predict the degree of beam polarization from a laser-driven plasma accelerator, particle-in-cell simulations including spin effects have been carried out for the first time. For this purpose, the Thomas-BMT equation, describing the spin precession in electromagnetic fields, has been implemented into the VLPL (Virtual Laser Plasma Lab) code. A crucial result of our simulations is that a target containing pre-polarized hydrogen nuclei is needed for producing highly polarized relativistic proton beams. For the experimental realization, a polarized HCl gas-jet target is under construction the Forschungszentrum Jülich where the degree of hydrogen polarization is measured with a Lamb-shift polarimeter. The final experiments, aiming at the first observation of a polarized particle beam from laser-generated plasmas, will be carried out at the 10 PW laser system SULF at SIOM/Shanghai.
	Slides SUPAF05 [3.927 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-ICAP2018-SUPAF05
About •	paper received ※ 19 October 2018 paper accepted ※ 24 October 2018 issue date ※ 26 January 2019
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

SUPAF06	Simulations of Coherent Electron Cooling With Free Electron Laser Amplifier and Plasma-Cascade Micro-Bunching Amplifier	electron, simulation, FEL, bunching	52
	J. Ma, V. Litvinenko, G. Wang BNL, Upton, Long Island, New York, USA V. Litvinenko Stony Brook University, Stony Brook, USA
	SPACE is a parallel, relativistic 3D electromagnetic Particle-in-Cell (PIC) code used for simulations of beam dynamics and interactions. An electrostatic module has been developed with the implementation of Adaptive Particle-in-Cloud method. Simulations performed by SPACE are capable of various beam distribution, different types of boundary conditions and flexible beam line, as well as sufficient data processing routines for data analysis and visualization. Code SPACE has been used in the simulation studies of coherent electron cooling experiment based on two types of amplifiers, the free electron laser (FEL) amplifier and the plasma-cascade micro-bunching amplifier.
	Slides SUPAF06 [1.260 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-ICAP2018-SUPAF06
About •	paper received ※ 15 October 2018 paper accepted ※ 24 October 2018 issue date ※ 26 January 2019
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

SUPAF09	Sparse Grid Particle-in-Cell Scheme for Noise Reduction in Beam Simulations	simulation, electron, target, damping	71
	A.J. Cerfon Courant Institute of Mathematical Sciences, New York University, New York, USA L.F. Ricketson LLNL, Livermore, California, USA
	The complexity of standard solvers grows exponentially with the number of dimensions of the underlying equations. This issue is particularly acute for continuum solvers, which need to discretize the six-dimensional phase-space distribution function, and whose run times are consequently large even for a moderate number of grid points for each dimension. Particle-in-Cell (PIC) schemes are a popular alternate approach to continuum methods, because they only discretize the three-dimensional physical space and are therefore less subject to the curse of dimensionality. Even if so, PIC solvers still have large run times, because of the statistical error which is inherent to particle methods and which decays slowly with the number of particles per cell. In this talk, we will present a new scheme to address the curse of dimensionality and at the same time reduce the numerical noise of PIC simulations. Our PIC scheme is inspired by the sparse grids combination technique, a method invented to reduce grid based error when solving high dimensional partial differential equations [1]. The technique, when applied to the PIC method, has two benefits: 1) it almost eliminates the dependence of the grid based error on dimensionality, just like in a standard sparse grids application; 2) it lowers the statistical error significantly, because the sparse grids have larger cells, and thus a larger number of particles per cell for a given total number of particles. We will analyze the performance of our scheme for standard test problems in beam physics. We will demonstrate remarkable speed up for a certain class of problems, and less impressive performance for others. The latter will allow us to identify the limitations of our scheme and explore ideas to address them. [1] Griebel M et al. 1990 A combination technique for the solution of sparse grid problems Iterative Methods in Linear Algebra ed R Bequwens and P de Groen (Amsterdam: Elsevier) pp 263-81
	Slides SUPAF09 [1.848 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-ICAP2018-SUPAF09
About •	paper received ※ 19 October 2018 paper accepted ※ 19 November 2018 issue date ※ 26 January 2019
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

SUPLG01	Computational Accelerator Physics: On the Road to Exascale	simulation, space-charge, optics, radiation	113
	R.D. Ryne LBNL, Berkeley, USA
	The first conference in what would become the ICAP series was held in 1988. At that time the most powerful computer in the world was a Cray YMP with 8 processors and a peak performance of 2 gigaflops. Today the fastest computer in the world has more than 2 million cores and a theoretical peak performance of nearly 200 petaflops. Compared to 1988, performance has increased by a factor of 100 million, accompanied by huge advances in memory, networking, big data management and analytics. By the time of the next ICAP in 2021 we will be at the dawn of the Exascale era. In this talk I will describe the advances in Computational Accelerator Physics that brought us to this point and describe what to expect in regard to High Performance Computing in the future. This writeup as based on my presentation at ICAP’18 along with some additional comments that I did not include originally due to time constraints.
	Slides SUPLG01 [25.438 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-ICAP2018-SUPLG01
About •	paper received ※ 14 November 2018 paper accepted ※ 07 December 2018 issue date ※ 26 January 2019
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

MOPAG01	Plasma Wakefield Start to End Acceleration Simulations From Photocathode to FEL With Simulated Density Profiles	electron, acceleration, FEL, simulation	154
	A. Marocchino INFN/LNF, Frascati (Roma), Italy
	Plasma Wakefield acceleration is a promising new acceleration technique that profit by a charged bunch, e.g. an electron bunch, to break the neutrality of a plasma channel to produce a wake where a trailing bunch is eventually accelerated. The quest to achieve extreme gradient conserving high brightness has prompted to a variety of new approaches and techniques. Most of the proposed schemes are however limited to the only plasma channel, assuming in the vast majority of cases, ideal scenarios (e.g. ideal bi-gaussian bunches and uniform density plasma channels). Realistic start-to-end simulations from the photocathode to a FEL via a plasma accelerating section are a fundamental step to further investigate realistic scheme possibilities, the underlying physics and future applications. To remove ideal simplifications, the SPARC_LAB simulation team is simulating bunches from the photo-cathode and tracking them all the way to the plasma. Similarly, the density profiles, where bunches evolve and accelerate, are calculated with a magneto-hydrodynamic code. The density profile is imported into the particle in cell codes used to calculate the particle evolution within the plasma section. The use of a multitude of codes, involving different architectures, physical units and programming languages, made necessary the definition of code interfacing and pipe-processes to ensure a proper pipeline of tools that are traditionally used in different fields are do not often come across. By combining the different numerical codes (particle tracker, particle in cell, magneto-hydrodynamics and FEL codes) we could propose a first realistic start-to-end simulation from the photo-cathode to a FEL lasering for a possible upcoming Italian PWFA-FEL facility. Such a work is conducted with a great focus on code reliability and data reproducibility. The Italian PWFA experimental team uses a capillary to control and tailor the plasma density profile, we could perform preliminary code comparison and
	Slides MOPAG01 [34.540 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-ICAP2018-MOPAG01
About •	paper received ※ 16 October 2018 paper accepted ※ 24 October 2018 issue date ※ 26 January 2019
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

MOPAG02	Efficient Modeling of Laser Wakefield Acceleration Through the PIC Code Smilei in CILEX Project	laser, simulation, electron, electromagnetic-fields	160
	F. Massimo, A. Beck, A. Specka, I. Zemzemi LLR, Palaiseau, France J. Derouillat Maison de la Simulation, CEA, Gif-sur-Yvette, France M. Grech, F. Pérez LULI, Palaiseau, France
	The design of plasma acceleration facilities requires considerable simulation effort for each part of the machine, from the plasma injector and/or accelerator stage(s), to the beam transport stage, from which the accelerated beams will be brought to the users or possibly to another plasma stage. The urgent issues and challenges in simulation of multi-stage acceleration with the Apollon laser of CILEX facility will be addressed. To simulate the beam injection in the second plasma stage, additional physical models have been introduced and tested in the open source Particle in Cell collaborative code Smilei. The efficient initialisation of arbitrary relativistic particle beam distributions through a Python interface allowing code coupling and the self consistent initialisation of their electromagnetic fields will be presented. The comparison between a full PIC simulation and a simulation with a recently developed envelope model, which allows to drastically reduce the computational time, will be also shown for a test case of laser wakefield acceleration of an externally injected electron beam.
	Slides MOPAG02 [20.462 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-ICAP2018-MOPAG02
About •	paper received ※ 15 October 2018 paper accepted ※ 24 October 2018 issue date ※ 26 January 2019
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEPLG01	Analysis of Emittance Growth in a Gridless Spectral Poisson Solver for Fully Symplectic Multiparticle Tracking	emittance, space-charge, lattice, simulation	335
	C.E. Mitchell, J. Qiang LBNL, Berkeley, California, USA
	Funding: This work was supported by the Director, Office of Science, Office of High Energy Physics, of the U.S. Department of Energy under Contract No. DE-AC02-05CH11231. Gridless spectral methods for self-consistent symplectic space charge modeling possess several advantages over traditional momentum-conserving particle-in-cell methods, including the absence of numerical grid heating and the presence of an underlying multi-particle Hamiltonian. Nevertheless, evidence of collisional particle noise remains. For a class of such 1D and 2D algorithms, we provide analytical models of the numerical field error, the optimal choice of spectral modes, and the numerical emittance growth per timestep. We compare these results with the emittance growth models of Struckmeier, Hoffman, Kesting, and others.
	Slides WEPLG01 [11.804 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-ICAP2018-WEPLG01
About •	paper received ※ 18 October 2018 paper accepted ※ 28 January 2019 issue date ※ 26 January 2019
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEPLG03	Theoretical and Computational Modeling of a Plasma Wakefield BBU Instability	wakefield, impedance, dipole, simulation	341
	S.D. Webb, D.L. Bruhwiler, N.M. Cook RadiaSoft LLC, Boulder, Colorado, USA A.V. Burov, V.A. Lebedev, S. Nagaitsev Fermilab, Batavia, Illinois, USA
	Funding: This work was supported in part by the Department of Energy, Office of Science, Office of High Energy Physics, under contract number DE-SC0018718. Plasma wakefield accelerators achieve accelerating gradients on the order of the wave-breaking limit, m c² k_p/e, so that higher accelerating gradients correspond to shorter plasma wavelengths. Small-scale accelerating structures, such as plasma and dielectric wakefields, are susceptible to the beam break-up instability (BBU), which can be understood from the Panofsky-Wenzel theorem: if the fundamental accelerating mode scales as b^-1 for a structure radius b, then the dipole mode must scale as b^-3, meaning that high accelerating gradients necessarily come with strong dipole wake fields. Because of this relationship, any plasma-accelerator-based future collider will require detailed study of the trade-offs between extracting the maximum energy from the driver and mitigating the beam break-up instability. Recent theoretical work* predicts the tradeoff between the witness bunch stability and the amount of energy that can be extracted from the drive bunch, a so-called efficiency-instability relation . We will discuss the beam break-up instability and the efficiency-instability relation and the theoretical assumptions made in reaching this conclusion. We will also present preliminary particle-in-cell simulations of a beam-driven plasma wakefield accelerator used to test the domain of validity for the assumptions made in this model. * V. Lebedev, A. Burov, and S. Nagaitsev, "Efficiency versus instability in plasma accelerators", Phys. Rev. Acc. Beams 20, 121301 (2017).
	Slides WEPLG03 [2.234 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-ICAP2018-WEPLG03
About •	paper received ※ 01 November 2018 paper accepted ※ 28 January 2019 issue date ※ 26 January 2019
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEPLG05	Review of Spectral Maxwell Solvers for Electromagnetic Particle-in-Cell: Algorithms and Advantages	simulation, laser, electron, distributed	345
	R. Lehé, J.-L. Vay LBNL, Berkeley, California, USA
	Electromagnetic Particle-In-Cell codes have been used to simulate both radio-frequency accelerators and plasma-based accelerators. In this context, the Particle-In-Cell algorithm often uses the finite-difference method in order to solve the Maxwell equations. However, while this method is simple to implement and scales well to multiple processors, it is liable to a number of numerical artifacts that can be particularly serious for simulations of accelerators. An alternative to the finite-difference method is the use of spectral solvers, which are typically less prone to numerical artifacts. In this talk, I will review recent progress in the use of spectral solvers for simulations of plasma-based accelerators. This includes techniques to scale those solvers to large number of processors, extensions to cylindrical geometry, and adaptations to specific problems such as boosted-frame simulations.
	Slides WEPLG05 [2.861 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-ICAP2018-WEPLG05
About •	paper received ※ 06 November 2018 paper accepted ※ 28 January 2019 issue date ※ 26 January 2019
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

Paper

Title

Other Keywords

Page

SUPAF04

Symplectic and Self-Consistent Algorithms for Particle Accelerator Simulation

simulation, space-charge, betatron, resonance

42

T. Planche, P. M. Jung
TRIUMF, Vancouver, Canada

This paper is a review of algorithms, applicable to particle accelerator simulation, which share the following two characteristics: (1) they preserve to machine precision the symplectic geometry of the particle dynamics, and (2) they track the evolution of the self-field consistently with the evolution of the charge distribution. This review includes, but is not limited to, algorithms using a Particle-in-Cell discretization scheme. At the end of this review we discuss to possibility to derived algorithms from an electrostatic Hamiltonian.

Slides SUPAF04 [0.424 MB]

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-ICAP2018-SUPAF04

About •

paper received ※ 19 October 2018 paper accepted ※ 24 October 2018 issue date ※ 26 January 2019

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

SUPAF05

Polarized Proton Beams From Laser-Induced Plasmas

laser, proton, polarization, target

46

M. Büscher, J. Böker, R. Engels, I. Engin, R. Gebel, A. Hützen, A. Lehrach
FZJ, Jülich, Germany
A.M. Pukhov, J. Thomas
HHUD, Dusseldorf, Germany
T. P. Rakitzis, D. Sofikitis
University of Crete, Heraklion, Crete, Greece

Laser-driven particle acceleration has undergone impressive progress in recent years. Nevertheless, one unexplored issue is how the particle spins are influenced by the huge magnetic fields inherently present in the plasmas. In the framework of the JuSPARC (Jülich Short-Pulse Particle and Radiation Center) facility and of the ATHENA consortium, the laser-driven generation of polarized particle beams in combination with the development of advanced target technologies is being pursued. In order to predict the degree of beam polarization from a laser-driven plasma accelerator, particle-in-cell simulations including spin effects have been carried out for the first time. For this purpose, the Thomas-BMT equation, describing the spin precession in electromagnetic fields, has been implemented into the VLPL (Virtual Laser Plasma Lab) code. A crucial result of our simulations is that a target containing pre-polarized hydrogen nuclei is needed for producing highly polarized relativistic proton beams. For the experimental realization, a polarized HCl gas-jet target is under construction the Forschungszentrum Jülich where the degree of hydrogen polarization is measured with a Lamb-shift polarimeter. The final experiments, aiming at the first observation of a polarized particle beam from laser-generated plasmas, will be carried out at the 10 PW laser system SULF at SIOM/Shanghai.

Slides SUPAF05 [3.927 MB]

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-ICAP2018-SUPAF05

About •

paper received ※ 19 October 2018 paper accepted ※ 24 October 2018 issue date ※ 26 January 2019

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

SUPAF06

Simulations of Coherent Electron Cooling With Free Electron Laser Amplifier and Plasma-Cascade Micro-Bunching Amplifier

electron, simulation, FEL, bunching

52

J. Ma, V. Litvinenko, G. Wang
BNL, Upton, Long Island, New York, USA
V. Litvinenko
Stony Brook University, Stony Brook, USA

SPACE is a parallel, relativistic 3D electromagnetic Particle-in-Cell (PIC) code used for simulations of beam dynamics and interactions. An electrostatic module has been developed with the implementation of Adaptive Particle-in-Cloud method. Simulations performed by SPACE are capable of various beam distribution, different types of boundary conditions and flexible beam line, as well as sufficient data processing routines for data analysis and visualization. Code SPACE has been used in the simulation studies of coherent electron cooling experiment based on two types of amplifiers, the free electron laser (FEL) amplifier and the plasma-cascade micro-bunching amplifier.

Slides SUPAF06 [1.260 MB]

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-ICAP2018-SUPAF06

About •

paper received ※ 15 October 2018 paper accepted ※ 24 October 2018 issue date ※ 26 January 2019

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

SUPAF09

Sparse Grid Particle-in-Cell Scheme for Noise Reduction in Beam Simulations

simulation, electron, target, damping

71

A.J. Cerfon
Courant Institute of Mathematical Sciences, New York University, New York, USA
L.F. Ricketson
LLNL, Livermore, California, USA

The complexity of standard solvers grows exponentially with the number of dimensions of the underlying equations. This issue is particularly acute for continuum solvers, which need to discretize the six-dimensional phase-space distribution function, and whose run times are consequently large even for a moderate number of grid points for each dimension. Particle-in-Cell (PIC) schemes are a popular alternate approach to continuum methods, because they only discretize the three-dimensional physical space and are therefore less subject to the curse of dimensionality. Even if so, PIC solvers still have large run times, because of the statistical error which is inherent to particle methods and which decays slowly with the number of particles per cell. In this talk, we will present a new scheme to address the curse of dimensionality and at the same time reduce the numerical noise of PIC simulations. Our PIC scheme is inspired by the sparse grids combination technique, a method invented to reduce grid based error when solving high dimensional partial differential equations [1]. The technique, when applied to the PIC method, has two benefits: 1) it almost eliminates the dependence of the grid based error on dimensionality, just like in a standard sparse grids application; 2) it lowers the statistical error significantly, because the sparse grids have larger cells, and thus a larger number of particles per cell for a given total number of particles. We will analyze the performance of our scheme for standard test problems in beam physics. We will demonstrate remarkable speed up for a certain class of problems, and less impressive performance for others. The latter will allow us to identify the limitations of our scheme and explore ideas to address them.
[1] Griebel M et al. 1990 A combination technique for the solution of sparse grid problems Iterative Methods in Linear Algebra ed R Bequwens and P de Groen (Amsterdam: Elsevier) pp 263-81

Slides SUPAF09 [1.848 MB]

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-ICAP2018-SUPAF09

About •

paper received ※ 19 October 2018 paper accepted ※ 19 November 2018 issue date ※ 26 January 2019

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

SUPLG01

Computational Accelerator Physics: On the Road to Exascale

simulation, space-charge, optics, radiation

113

R.D. Ryne
LBNL, Berkeley, USA

The first conference in what would become the ICAP series was held in 1988. At that time the most powerful computer in the world was a Cray YMP with 8 processors and a peak performance of 2 gigaflops. Today the fastest computer in the world has more than 2 million cores and a theoretical peak performance of nearly 200 petaflops. Compared to 1988, performance has increased by a factor of 100 million, accompanied by huge advances in memory, networking, big data management and analytics. By the time of the next ICAP in 2021 we will be at the dawn of the Exascale era. In this talk I will describe the advances in Computational Accelerator Physics that brought us to this point and describe what to expect in regard to High Performance Computing in the future. This writeup as based on my presentation at ICAP’18 along with some additional comments that I did not include originally due to time constraints.

Slides SUPLG01 [25.438 MB]

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-ICAP2018-SUPLG01

About •

paper received ※ 14 November 2018 paper accepted ※ 07 December 2018 issue date ※ 26 January 2019

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

MOPAG01

Plasma Wakefield Start to End Acceleration Simulations From Photocathode to FEL With Simulated Density Profiles

electron, acceleration, FEL, simulation

154

A. Marocchino
INFN/LNF, Frascati (Roma), Italy

Plasma Wakefield acceleration is a promising new acceleration technique that profit by a charged bunch, e.g. an electron bunch, to break the neutrality of a plasma channel to produce a wake where a trailing bunch is eventually accelerated. The quest to achieve extreme gradient conserving high brightness has prompted to a variety of new approaches and techniques. Most of the proposed schemes are however limited to the only plasma channel, assuming in the vast majority of cases, ideal scenarios (e.g. ideal bi-gaussian bunches and uniform density plasma channels). Realistic start-to-end simulations from the photocathode to a FEL via a plasma accelerating section are a fundamental step to further investigate realistic scheme possibilities, the underlying physics and future applications. To remove ideal simplifications, the SPARC_LAB simulation team is simulating bunches from the photo-cathode and tracking them all the way to the plasma. Similarly, the density profiles, where bunches evolve and accelerate, are calculated with a magneto-hydrodynamic code. The density profile is imported into the particle in cell codes used to calculate the particle evolution within the plasma section. The use of a multitude of codes, involving different architectures, physical units and programming languages, made necessary the definition of code interfacing and pipe-processes to ensure a proper pipeline of tools that are traditionally used in different fields are do not often come across. By combining the different numerical codes (particle tracker, particle in cell, magneto-hydrodynamics and FEL codes) we could propose a first realistic start-to-end simulation from the photo-cathode to a FEL lasering for a possible upcoming Italian PWFA-FEL facility. Such a work is conducted with a great focus on code reliability and data reproducibility. The Italian PWFA experimental team uses a capillary to control and tailor the plasma density profile, we could perform preliminary code comparison and

Slides MOPAG01 [34.540 MB]

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-ICAP2018-MOPAG01

About •

paper received ※ 16 October 2018 paper accepted ※ 24 October 2018 issue date ※ 26 January 2019

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

MOPAG02

Efficient Modeling of Laser Wakefield Acceleration Through the PIC Code Smilei in CILEX Project

laser, simulation, electron, electromagnetic-fields

160

F. Massimo, A. Beck, A. Specka, I. Zemzemi
LLR, Palaiseau, France
J. Derouillat
Maison de la Simulation, CEA, Gif-sur-Yvette, France
M. Grech, F. Pérez
LULI, Palaiseau, France

The design of plasma acceleration facilities requires considerable simulation effort for each part of the machine, from the plasma injector and/or accelerator stage(s), to the beam transport stage, from which the accelerated beams will be brought to the users or possibly to another plasma stage. The urgent issues and challenges in simulation of multi-stage acceleration with the Apollon laser of CILEX facility will be addressed. To simulate the beam injection in the second plasma stage, additional physical models have been introduced and tested in the open source Particle in Cell collaborative code Smilei. The efficient initialisation of arbitrary relativistic particle beam distributions through a Python interface allowing code coupling and the self consistent initialisation of their electromagnetic fields will be presented. The comparison between a full PIC simulation and a simulation with a recently developed envelope model, which allows to drastically reduce the computational time, will be also shown for a test case of laser wakefield acceleration of an externally injected electron beam.

Slides MOPAG02 [20.462 MB]

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-ICAP2018-MOPAG02

About •

paper received ※ 15 October 2018 paper accepted ※ 24 October 2018 issue date ※ 26 January 2019

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEPLG01

Analysis of Emittance Growth in a Gridless Spectral Poisson Solver for Fully Symplectic Multiparticle Tracking

emittance, space-charge, lattice, simulation

335

C.E. Mitchell, J. Qiang
LBNL, Berkeley, California, USA

Funding: This work was supported by the Director, Office of Science, Office of High Energy Physics, of the U.S. Department of Energy under Contract No. DE-AC02-05CH11231.
Gridless spectral methods for self-consistent symplectic space charge modeling possess several advantages over traditional momentum-conserving particle-in-cell methods, including the absence of numerical grid heating and the presence of an underlying multi-particle Hamiltonian. Nevertheless, evidence of collisional particle noise remains. For a class of such 1D and 2D algorithms, we provide analytical models of the numerical field error, the optimal choice of spectral modes, and the numerical emittance growth per timestep. We compare these results with the emittance growth models of Struckmeier, Hoffman, Kesting, and others.

Slides WEPLG01 [11.804 MB]

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-ICAP2018-WEPLG01

About •

paper received ※ 18 October 2018 paper accepted ※ 28 January 2019 issue date ※ 26 January 2019

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEPLG03

Theoretical and Computational Modeling of a Plasma Wakefield BBU Instability

wakefield, impedance, dipole, simulation

341

S.D. Webb, D.L. Bruhwiler, N.M. Cook
RadiaSoft LLC, Boulder, Colorado, USA
A.V. Burov, V.A. Lebedev, S. Nagaitsev
Fermilab, Batavia, Illinois, USA

Funding: This work was supported in part by the Department of Energy, Office of Science, Office of High Energy Physics, under contract number DE-SC0018718.
Plasma wakefield accelerators achieve accelerating gradients on the order of the wave-breaking limit, m c² k_p/e, so that higher accelerating gradients correspond to shorter plasma wavelengths. Small-scale accelerating structures, such as plasma and dielectric wakefields, are susceptible to the beam break-up instability (BBU), which can be understood from the Panofsky-Wenzel theorem: if the fundamental accelerating mode scales as b^-1 for a structure radius b, then the dipole mode must scale as b^-3, meaning that high accelerating gradients necessarily come with strong dipole wake fields. Because of this relationship, any plasma-accelerator-based future collider will require detailed study of the trade-offs between extracting the maximum energy from the driver and mitigating the beam break-up instability. Recent theoretical work* predicts the tradeoff between the witness bunch stability and the amount of energy that can be extracted from the drive bunch, a so-called efficiency-instability relation . We will discuss the beam break-up instability and the efficiency-instability relation and the theoretical assumptions made in reaching this conclusion. We will also present preliminary particle-in-cell simulations of a beam-driven plasma wakefield accelerator used to test the domain of validity for the assumptions made in this model.
* V. Lebedev, A. Burov, and S. Nagaitsev, "Efficiency versus
instability in plasma accelerators", Phys. Rev. Acc. Beams 20, 121301
(2017).

Slides WEPLG03 [2.234 MB]

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-ICAP2018-WEPLG03

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paper received ※ 01 November 2018 paper accepted ※ 28 January 2019 issue date ※ 26 January 2019

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WEPLG05

Review of Spectral Maxwell Solvers for Electromagnetic Particle-in-Cell: Algorithms and Advantages

simulation, laser, electron, distributed

345

R. Lehé, J.-L. Vay
LBNL, Berkeley, California, USA

Electromagnetic Particle-In-Cell codes have been used to simulate both radio-frequency accelerators and plasma-based accelerators. In this context, the Particle-In-Cell algorithm often uses the finite-difference method in order to solve the Maxwell equations. However, while this method is simple to implement and scales well to multiple processors, it is liable to a number of numerical artifacts that can be particularly serious for simulations of accelerators. An alternative to the finite-difference method is the use of spectral solvers, which are typically less prone to numerical artifacts. In this talk, I will review recent progress in the use of spectral solvers for simulations of plasma-based accelerators. This includes techniques to scale those solvers to large number of processors, extensions to cylindrical geometry, and adaptations to specific problems such as boosted-frame simulations.

Slides WEPLG05 [2.861 MB]

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-ICAP2018-WEPLG05

About •

paper received ※ 06 November 2018 paper accepted ※ 28 January 2019 issue date ※ 26 January 2019

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reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)