WG1 - Electron beams from plasmas
After the success of the SLAC experimental program PWFA experiments are multiplying. The self-modulation instability (SMI) has emerged as a new topic of investigation both for the propagation of long charged particle bunches (e-, e+, p+, …) in long plasmas (λpe<<σz) and for the resonant excitation of wakefields to large amplitudes. But while seemingly attractive because of the use of existing long bunches, this PWFA excitation method has a number of challenges.
For laser wakefield acceleration, Europe is home to a number of both mature and emerging programs in laser driven wakefield acceleration. A number of groups have generated electron beams on the GeV energy scale and significant work is being invested into both understanding and improving the reproducibility of existing experiments, as well as developing the next generation of facility that will increase repletion-rate/ energy /charge of laser wakefield acceleration.
Starting from the current status of both plasma and laser wakefield research, we will review current research programs, before assessing novel implementations. For plasma wakefield experiments, both single or multiple drive bunch experiments will be assessed, whilst in laser wakefield experiments we will discuss novel injection techniques as well as novel laser drivers and staging. We will discuss experimental plans, challenges and goals, plasma sources and diagnostics. We hope to generate a common understanding of the physics and issues at play.
We will interact with the simulation WG (WG6) to review progress in simulations of PWFAs. We will attempt to determine the direction the field is taking and discuss the various ways the field could impact light sources (x-ray FEL), linear e-/e+ colliders and lepton/hadron colliders.
Co-Leader: Patric Muggli (Max-Planck-Institut für Physik - München, Germany)
Co-Leader: Zulfikar Najmudin (Imperial College - London, UK)
WG2 - Ion beams from plasmas
Working Group 2 will assess and review the state-of-the-art regarding ion beams produced by laser-plasma sources and of the associated fields, namely target fabrication, diagnostics, beam shaping, and beam transport to name a few. We will discuss recent important advances in the field, e.g. how new types of targets enable new mechanisms, or new ways to shape the produced ion beams. Part of the discussion will focus on the way to adapt methods for generating ion beams to the upcoming high repetition rate laser facilities at high power, including targetry and diagnostics. A section will also be devoted to recent developments in the application of ion beams to other fields, whether physics or biology, and in particular to the need for suitable diagnostics in order to properly characterize the necessary beam parameters for each application. To stimulate discussions joint sessions will be held with the other working groups, in particular WG6, whenever appropriate. We encourage contributors to submit presentations and posters related to these topics to WG2.
Leader: Julien Fuchs (École Polytechnique - Palaiseau, France)
WG3 - Electron beams from electromagnetic structures, including dielectric and laser-driven
This working group will address advances in electromagnetic structures as they progress from radiofrequency towards new frontiers at short wavelength and higher field. Discussion will be open to schemes powered by advanced RF sources, and new sources of EM power such as Cerenkov wakefields as well as intense lasers. Advanced and exotic structures using novel materials will be examined. Inverse processes such as IFEL will be discussed. Special emphasis will be placed on extreme high brightness electron beam sources, and beam dynamics at the optical scale. Topical discussions will include, but not be limited to:
- Dielectric laser acceleration
- Dielectric wakefield acceleration
- Very high power, high frequency RF structures
- Photonic accelerator structures
- Field breakdown limits in metal and dielectric structures
- Inverse FEL acceleration and other undulator mediated interactions
- RF and laser-based undulators
- Extreme low emittance beams and their sources, including photoinjectors
Co-Leader: James B. Rosenzweig (UCLA, USA)
Co-Leader: Manoel Conde (Argonne National Laboratory, USA)
WG4 - Future accelerator concepts incl. gg, beam transport (applications)
The WG4 will consider the topics related to the future and novel accelerator concepts of colliders, new beam manipulation and focusing techniques, novel FEL schemes, and will focus in particular on:
- New concepts of plasma (and other such method) based colliders
- Novel concepts of colliders including Higgs factories based on advanced linacs (and recirculating linacs), gamma-gamma collider, etc
- Novel schemes of beam focusing including local chromaticity correction
- Beam control and manipulation schemes
- Emittance exchange, micro-bunch train, beam shaping (ramped beams, special distributions), flat beam transformations
- Novel FEL schemes, such as transversely tapered undulator, RF, optical and plasma based undulators
Leader: Andrei A. Seryi (University of Oxford, Royal Holloway University of London and Imperial College London, UK)
WG5 - Plasma sources and instrumentation
Working Group 5 will investigate the state-of-the-art in two areas of novel accelerator science: plasma-source technologies including plasma diagnostics, and electron-beam diagnostics.
The central interaction point between laser pulses, electron beams, and plasma wakefields has been recognized in the last years as an important factor in the endeavor to control, stabilize, and analyze the wakefield-acceleration process. We are planning to discuss the different types of targets in use today such as gas jets, plasma cells, capillary discharge waveguides, and alkali vapor ovens, and evaluate their potential. In particular, attention will be paid to
- tailoring of the three-dimensional plasma-density distribution
- doping with different gas species as required for ionization injection
- prospects and limits set by the type of target for achievable beam parameters, e.g. emittance growth induced by gas oven windows or target length constraints that limit the acceleration distance
- plasma homogeneity, as required for the AWAKE experiments
- suitability for future accelerator concepts, applications and their deployment in user facilities.
In addition, the diagnosis of the plasma target is of crucial importance. We would like to review the progress in this particular subtopic and discuss the various techniques in use, e.g. transverse interferometry, Raman scattering, Fourier domain holography and more.
The second focus of this working group will be the measurement of electron-beam properties. Transverse and longitudinal phase spaces must be characterized in order to properly match the beam into further acceleration stages, or for applications in photon sources and high-energy-physics experiments.
Both measurements are difficult to conduct stemming from the acceleration process, in particular either from strongly correlated transverse phase spaces or from the ultra-short nature of the longitudinal phase-space distribution. While several techniques have been employed in the last years, those methods are not well established yet with unanimous consensus in the community. We'll review recent measurements and proposals. By comparing both advantages and problems, we hope to trigger fruitful discussions.
We encourage contributors to submit presentations and posters related to these topics to WG5.
Co-Leader: Alessandro Cianchi (University of Roma Tor Vergata and INFN - Roma 2, Italy)
Co-Leader: Jens Osterhoff (DESY, Germany)
WG6 - Theory and simulations
The focus of the Theory and Simulations working group (WG6) will be to assess and to review the state-of-the-art computational tools for enabling realistic and rapid simulations of plasma and laser wakefield accelerator stages, high gradient structures, high brightness sources, radiation from beams and beam-driven structures, and synthetic diagnostics. The working group will also discuss the verification and validation of the models, choices in computation tools (e.g. PIC, quasi-static PIC, and fluid), algorithms and performance for novel architectures, and prospective needs for modelling near term and long term plasma accelerator experimental programs. To stimulate discussions joint sessions will be held with the other working groups whenever appropriate. Review of recent theoretical developments in the key topics of the conference will also be addressed.
Leader: Luis O. Silva (Istituto Superior Técnico - Lisboa, Portugal)