Glossary

In daily communication, we tend to abbreviate a lot of terms. It is important to us to make it easy to interact with the WarpX community and thus, this list shall help to clarify often used terms.

Abbreviations

  • 2FA: Two-factor-authentication

  • ABLASTR: Accelerated BLAST Recipes, the library inside WarpX to share functionality with other BLAST codes

  • ALCF: Argonne Leadership Computing Facility, a supercomputing center located near Chicago, IL (USA)

  • ALS: Advance Light Source, a U.S. Department of Energy scientific user facility at Lawrence Berkeley National Laboratory

  • BLAST: Beam, Plasma & Accelerator Simulation Toolkit

  • AMR: adaptive mesh-refinement

  • BC: boundary condition (of a simulation)

  • BCK: Benkler-Chavannes-Kuster method, a stabilization technique for small cells in the electromagnetic solver

  • BTD: backtransformed diagnostics, a method to collect data for analysis from a boosted frame simulation

  • CEX: charge-exchange collisions

  • CFL: the Courant-Friedrichs-Lewy condition, a numerical parameter for the numerical convergence of PDE solvers

  • CI: continuous integration, automated tests that we perform before a proposed code-change is accepted; see PR

  • CPU: central processing unit, we usual mean a socket or generally the host-side of a computer (compared to the accelerator, e.g. GPU)

  • DOE: The United States Department of Energy, the largest sponsor of national laboratory research in the United States of America

  • DSMC: Direct Simulation Monte Carlo, a method to capture collisions between kinetic particles

  • ECP: Exascale Computing Project, a U.S. DOE funding source that supports WarpX development

  • ECT: Enlarged Cell Technique, an electromagnetic solver with accurate resolution of perfectly conducting embedded boundaries

  • EB: embedded boundary, boundary conditions inside the simulation box, e.g. following material surfaces

  • EM: electromagnetic, e.g. EM PIC

  • ES: electrostatic, e.g. ES PIC

  • FDTD: Finite-difference time-domain or Yee’s method, a class of grid-based finite-difference field solvers

  • FRC: Field Reversed Configuration, an approach of magnetic confinement fusion

  • GPU: originally graphics processing unit, now used for fast general purpose computing (GPGPU); also called (hardware) accelerator

  • IO: input/output, usually files and/or data

  • IPO: interprocedural optimization, a collection of compiler optimization techniques that analyze the whole code to avoid duplicate calculations and optimize performance

  • ISI: Induced Spectral Incoherence (a laser pulse manipulation technique)

  • LDRD: Laboratory Directed Research and Development, a funding program in U.S. DOE laboratories that kick-started ABLASTR development

  • LPA: laser-plasma acceleration, historically used for laser-electron acceleration

  • LPI: laser-plasma interaction (often for laser-solid physics) or laser-plasma instability (often in fusion physics), depending on context

  • LTO: link-time optimization, program optimizations for file-by-file compilation that optimize object files before linking them together to an executable

  • LWFA: laser-wakefield acceleration (of electrons/leptons)

  • MCC: Monte-Carlo collisions wherein a kinetic species collides with a fluid species, for example used in glow discharge simulations

  • MR: mesh-refinement

  • MS: magnetostatic, e.g. MS PIC

  • MVA: magnetic-vortex acceleration (of protons/ions)

  • NERSC: National Energy Research Scientific Computing Center, a supercomputing center located in Berkeley, CA (USA)

  • NSF: the National Science Foundation, a large public agency in the United States of America, supporting research and education

  • OLCF: Oak Ridge Leadership Computing Facility, a supercomputing center located in Oak Ridge, TN (USA)

  • OTP: One-Time-Password; see 2FA

  • PDE: partial differential equation, an equation which imposes relations between the various partial derivatives of a multivariable function

  • PIC: particle-in-cell, the method implemented in WarpX

  • PICMI: Particle-In-Cell Modeling Interface, a standard proposing naming and structure conventions for particle-in-cell simulation input

  • PICSAR: Particle-In-Cell Scalable Application Resource, a high performance parallelization library intended to help scientists porting their Particle-In-Cell (PIC) codes to next generation of exascale computers

  • PR: github pull request, a proposed change to the WarpX code base

  • PSATD: pseudo-spectral analytical time-domain method, a spectral field solver with better numerical properties than FDTD solvers

  • PWFA: plasma-wakefield acceleration

  • QED: quantum electrodynamics

  • RPA: radiation-pressure acceleration (of protons/ions), e.g. hole-boring (HB) or light-sail (LS) acceleration

  • RPP: Random Phase Plate (a laser pulse manipulation technique)

  • RZ: for the coordinate system r-z in cylindrical geometry; we use “RZ” when we refer to quasi-cylindrical geometry, decomposed in azimuthal modes (see details here)

  • SENSEI: Scalable in situ analysis and visualization, light weight framework for in situ data analysis offering access to multiple visualization and analysis backends

  • SEE: secondary electron emission

  • SSD: Smoothing by Spectral Dispersion (a laser pulse manipulation technique)

  • TNSA: target-normal sheet acceleration (of protons/ions)

Terms

  • accelerator: depending on context, either a particle accelerator in physics or a hardware accelerator (e.g. GPU) in computing

  • AMReX: C++ library for block-structured adaptive mesh-refinement, a primary dependency of WarpX

  • Ascent: many-core capable flyweight in situ visualization and analysis infrastructure, a visualization backend usable with WarpX data

  • boosted frame: a Lorentz-boosted frame of reference for a simulation

  • evolve: this is a generic term to advance a quantity (same nomenclature in AMReX).

    For instance, WarpX::EvolveE(dt) advances the electric field for duration dt, PhysicalParticleContainer::Evolve(...) does field gather + particle push + current deposition for all particles in PhysicalParticleContainer, and WarpX::Evolve is the central WarpX function that performs 1 PIC iteration.

  • Frontier: an Exascale supercomputer at OLCF

  • hybrid-PIC: a plasma simulation scheme that combines fluid and kinetic approaches, with (usually) the electrons treated as a fluid and the ions as kinetic particles (see Kinetic-fluid Hybrid Model)

  • laser: most of the time, we mean a laser pulse

  • openPMD: Open Standard for Particle-Mesh Data Files, a community meta-data project for scientific data

  • Ohm’s law solver: the logic that solves for the electric-field when using the hybrid-PIC algorithm

  • Perlmutter: a Berkeley Lab nobel laureate and a Pre-Exascale supercomputer at NERSC

  • plotfiles: the internal binary format for data files in AMReX

  • Python: a popular scripted programming language

  • scraping: a term often used to refer to the process of removing particles that have crossed into an embedded boundary or pass an absorbing domain boundary from the simulation