### Conveners

#### WG6_Parallel

- Arnaud Beck (Laboratoire Leprince Ringuet)
- Alberto Marocchino (LNF)

#### WG6_Parallel

- Alberto Marocchino (LNF)
- Arnaud Beck (Laboratoire Leprince Ringuet)

#### WG6_Parallel

- Alberto Marocchino (LNF)
- Arnaud Beck (Laboratoire Leprince Ringuet)

#### WG6_Parallel

- Arnaud Beck (Laboratoire Leprince Ringuet)
- Alberto Marocchino (LNF)

Dr
Timon Mehrling
(Deutsches Elektronen-Synchrotron DESY)

9/26/17, 4:00 PM

WG6 - Theory and Simulations

talk

In 1867, just two years after laying the foundations of electromagnetism, J. Clerk Maxwell presented a fundamental paper on gas dynamics, in which he described the evolution of the gas in terms of certain "moments" of its velocity distribution function. This inspired Ludwig Boltzmann to formulate his famous kinetic equation, from which followed the H-theorem and the connection with entropy....

Dr
Remi Lehe
(Lawrence Berkeley National Laboratory)

9/26/17, 4:20 PM

WG6 - Theory and Simulations

talk

The beam-hosing instability is of key importance for the design of future plasma-wakefield accelerators. While previous work on this topic focused mainly on the blow-out wakefield regime, here we analyze theoretically the BBU for plasma-accelerators in the quasi-linear wakefield regime. Importantly, we show both analytically and numerically that, in this regime, the instability can saturate...

Mr
Alexander Aschikhin
(Deutsches Elektronen-Synchrotron DESY)

9/26/17, 4:40 PM

WG6 - Theory and Simulations

talk

Witness beam quality preservation (in particular energy spread and emittance) for external injection scenarios in plasma-based accelerators is a crucial requirement for downstream applications such as Free Electron Lasers. Due to the complexity of the beam-plasma interaction, extensive studies of possible mechanisms to preserve beam quality are usually done using particle-in-cell (PIC)...

Alberto Marocchino
(LNF)

9/26/17, 6:00 PM

WG6 - Theory and Simulations

talk

We present a numerical investigation of a Plasma Wakefield Acceleration scenario in the weakly non-linear regime relevant to the campaign at the SPARC LAB test facility. The investigation considers a two bunches configuration: a charged driver that induces the wakefield, followed by a less charged bunch (trailing bunch) that is accelerated; bunches are generated and pre-accelerated up to 100...

Francesco Mira
(ROMA1)

9/26/17, 6:20 PM

WG6 - Theory and Simulations

talk

The scope of this work is to characterize the novel and promising strategy for ionization-induced trapping of electrons in a beam driven plasma accelerator, originally proposed by A. Martinez de la Ossa et al. [Phys Rev Lett (2013)].The beam driven ionization injection scheme is based on the field ionization of a dopant gas confined in a small region within a hydrogen plasma background. The...

Mr
Patrick Lee
(Laboratoire de Physique des Gaz et des Plasmas)

9/26/17, 6:40 PM

WG6 - Theory and Simulations

talk

Ionization-induced injection is a promising scheme to achieve stable laser-plasma injectors with low energy spread (~10%) electron beams. This scheme is easy to implement experimentally and offers an additional parameter of control on electron beam properties for compact injectors in the 100 to 200 MeV range. Simulations were performed with realistic laser-plasma parameters using the pic code...

Dr
Serge Kalmykov
(University of Nebraska - Lincoln)

9/26/17, 7:00 PM

WG6 - Theory and Simulations

talk

Optimizing nonlinear evolution of the drive pulse, through adequate photon engineering, is a vital element of the laser-plasma accelerator (LPA) design, offering new avenues to control electron beam phase space on a femtosecond time scale. Stacked pulse-driven LPA is a perfect tool to exercise this control, affording kHz-scale repetition rate at a manageable average power, favoring radiation...

Stefano Sinigardi
(BO)

9/26/17, 7:15 PM

WG6 - Theory and Simulations

talk

TNSA numerical simulations have many uncertainties, due to the large arbitrariness in input parameters, besides huge computational costs for 3D. The energy spectrum of the accelerated particles is exponential with a cut-off and is correctly reproduced, but the maximum energy obtained depends on many user-chosen parameters, for example the simulation end time. The growth in time of the maximum...

Prof.
Konstantin Lotov
(Novosibirsk State University)

9/27/17, 4:00 PM

WG6 - Theory and Simulations

talk

AWAKE experiment on proton driven plasma wakefield acceleration in CERN presents a real challenge for numerical simulations. Parameters of the experiment fall far beyond the area for which most codes were originally developed and tuned. Proton beams are very long, a few hundred plasma wavelengths. The excited wakefield is a result of an instability and depends on small amplitude seed...

Manuel Kirchen
(University of Hamburg)

9/27/17, 4:20 PM

WG6 - Theory and Simulations

talk

We present a novel Particle-in-Cell algorithm that is intrinsically free of the numerical Cherenkov instability for relativistic plasmas flowing at a uniform velocity. The new method is independent of the geometry and - unlike previous suppression strategies - we completely avoid artificial modifications of the electromagnetic fields. Application is shown at the example of Lorentz-boosted...

Stephen Webb
(RadiaSoft, LLC)

9/27/17, 4:40 PM

WG6 - Theory and Simulations

talk

Conventional particle-in-cell methods for modeling plasma accelerators are prone to a variety of numerical instabilities and artifacts which can make them unreliable for long simulations. This is due to two issues: a lack of fidelity in the dispersion of the electromagnetic field update, and grid heating. We present a new class of algorithms, symplectic particle-in-mode (symPIM) algorithms,...

Mr
Marco Garten
(HZDR, TU Dresden)

9/27/17, 5:00 PM

WG6 - Theory and Simulations

talk

Laser-driven solid density plasmas can be used to generate highly energetic electrons and ions. Diagnosing properties within those plasmas at nm length scales and down to fs time scales is crucial in understanding the involved processes. This has recently become feasible through the advent of X-Ray Free Electron Lasers (XFELs). For instance, XFELs allow to image the electron density...

Mr
Roman Spitsyn
(Budker Institute of Nuclear Physics)

9/27/17, 5:15 PM

WG6 - Theory and Simulations

talk

Numerical simulations of beam-plasma instabilities may produce quantitatively incorrect results because of unrealistically high initial noise from which the instabilities develop. Of particular importance is the wakefield noise, the potential perturbations that have a phase velocity which is equal to the beam velocity. Controlling the noise level in simulations may offer the possibility of...

Jean-Luc Vay
(Berkeley Lab)

9/27/17, 6:00 PM

WG6 - Theory and Simulations

talk

Turning the current experimental plasma accelerator state-of-the-art from a promising technology into mainstream scientific tools depends critically on high-performance, high-fidelity modeling of complex processes that develop over a wide range of space and time scales. As part of the U.S. Department of Energy’s Exascale Computing Project, a team from Lawrence Berkeley National Laboratory, in...

Mr
Soeren Jalas
(Center for Free-Electron Laser Science and Department of Physics, University of Hamburg)

9/27/17, 6:25 PM

WG6 - Theory and Simulations

talk

Numerical Cherenkov radiation (NCR) is a numerical artefact in PIC codes which results from inaccurate modeling of the electromagnetic dispersion relation. It can be a dominant source of spurious beam quality degradation in terms of emittance and energy spread. As a result of their high spectral precision pseudo-spectral solvers suppress NCR. However, due to the global nature of these solvers...

Mr
Axel Huebl
(Helmholtz-Zentrum Dresden - Rossendorf)

9/27/17, 6:50 PM

WG6 - Theory and Simulations

talk

PIConGPU reportedly is the fastest particle-in-cell code in the world with respect to sustained Flop/s. Written in performance-portable, single-source C++ we constantly push the envelope towards Exascale laser-plasma modeling. However, solving previously week-long simulation tasks in a few hours with a speedy framework is only the beginning.
This talk will present the architecture and...

Mr
Richard Pausch
(Helmholtz-Zentrum Dresden - Rossendorf)

9/27/17, 7:10 PM

WG6 - Theory and Simulations

talk

We present recent results from the in-situ radiation diagnostics available in the particle-in-cell code PIConGPU and illustrate its power to provide insight into LWFA experiments when linked to experimental measurements.
PIConGPU is currently one of the fastest 3D3V PIC codes. Its speed allows including an in-situ radiation diagnostic based on Liénard-Wiechert potentials. This synthetic...