WG1 – Laser-Plasma Wakefield Acceleration

Yong Ma (University of Michigan), Marlene Turner (LBNL), Irina Petrushina (Stony Brook University)

Working Group 1 (WG1) will focus on the acceleration of electrons and positrons using laser-plasma accelerators (LPAs). Work on developing LPAs are motivated by two major applications: high energy physics (HEP) colliders at the TeV scale and compact light sources. The path from recent results towards achieving high-quality beams required for these applications will be discussed.

Contributors are encouraged to present laser-plasma physics, simulations, and experiments that address the following topics, which will be the organizing themes for arranging working group discussions.

  • Injection: Controlled particle injection into laser-driven plasma wakefields to produce beams that are: stable and reproducible, lower in transverse and longitudinal emittances, and higher in charge. What are promising techniques that can produce high-quality beams needed for applications such as colliders, free-electron lasers, Thomson/Compton sources, etc.?
  • Acceleration: Laser-driven plasma wakefields to accelerate particle beams that are efficient in energy transfer of the laser energy to particle beams, applicable for high repetition rate operations, and energy-scalable for HEP applications. Self- and external-guiding schemes as well as manipulation of spatio-temporal couplings can be utilized to extend the acceleration length. Staging can overcome laser depletion limit. What are challenges, limitations, and solutions for laser-driven acceleration structures for light source, HEP and other applications?
  • Beam manipulation: Compact beam manipulation and transportation techniques are needed alongside acceleration structures to realize applications of LPAs. How can compact radiation cooling, focusing systems, and beam property exchanges be realized?
  • Diagnostics: Diagnostics are key for all elements described above to be developed. This includes radiation sources and other methods as tools to diagnose acceleration structures as well as the accelerated beams.

Joint sessions with other working groups will be arranged based on contributions.

WG2 – Computation for Accelerator Physics

David Bruhwiler (RadiaSoft), Alexey Arefiev (University of California, San Diego)

Ongoing advances in experimental measurements and new applications, in conjunction with greater computing resources and algorithmic advances, are posing new challenges and creating new opportunities for the numerical modeling and design of advanced accelerators. The goal for this working group is to understand the present state-of-the art and to draft a 10-year roadmap for future developments. In particular, we will review and discuss the following topics:

  • Reduced models with orders-of-magnitude reduction in computational requirements
  • Validation of numerical simulation results with experimental data
  • Algorithms and infrastructure to advance multi-scale and multi-physics modeling capabilities
  • The role of machine learning in modeling, monitoring and controlling experiments
  • Advances toward start-to-end modeling and virtual representation of complete systems
  • Improvements in performance, portability and sustainability on new computing architectures
  • Community sharing and support for codes, visualization, best practices, etc.

Participants are encouraged to address their recent contributions to these topics in their presentations and, in the spirit of this workshop, to actively participate in the questions and answers that will follow them.

WG3 – Laser and High-Gradient Structure-Based Acceleration

Sergey Belomestnykh (FNAL), Xueying Lu (Northern Illinois University)

The purpose of Working Group 3 is to discuss recent advances in externally-powered structure-based accelerators, both laser and rf driven. The capability to accelerate particles at higher accelerating gradients and efficiencies is essential for reduction of size and cost of future accelerators for science and industry. This includes the future multi-TeV e+e- collider for High Energy Physics, free-electron lasers (FELs) for Basic Energy Sciences and National Security, industrial accelerators for Energy and Environmental Applications, and accelerators for other applications (direct material investigation, medical field, nanotechnology, etc.).

The working group welcomes presentations on the following topics:

  • Recent developments in novel accelerating structures with new geometries, new materials (dielectric, metamaterial, hybrid, etc.), new fabrication technologies (additive manufacturing, micromachining, etc.), frequencies from microwave to THz and optical spectrum, and operating conditions from normal conducting to cryogenic and superconducting.
  • Recent advances in understanding rf breakdown and quench phenomena at different frequencies and materials, and other physics limitations to the accelerating gradient.
  • Recent advances in improving the accelerating efficiency, such as understanding of sources of microwave dissipation and pathways, development of ultra-low rf loss material, heavy beam-loading compensation.
  • Demonstration of high accelerating gradients and efficiencies.

The group will also try to address specific issues such as novel structure-beam interaction schemes (IFEL, undulator-mediated, etc.), high efficiency electromagnetic power source development, optimizing novel accelerating structures using advanced algorithms, beam dynamics and collective effects associated with reduced beam apertures, optimizing power coupling schemes to the structures, increasing wall-plug-to-beam efficiency, and integrated particle source designs.

WG4 – Beam-Driven Acceleration

Jens Osterhoff (DESY), Spencer Gessner (SLAC)

This working group examines plasma- and structure-based beam-driven wakefield acceleration. The overarching goal of the WG4 is to provide a platform to discuss recent development on the various topics relevant to beam-driven acceleration (both in the collinear and two-beam configurations). In particular, our group will discuss:

  • Beam dynamics associated with drive beam: beam shaping for transformer-ratio improvement, methods to mitigate beam-break-up instabilities.
  • Recent developments in the production of plasmas (control of density for emittance preservation) and design of structures.
  • Generation of suitable main/witness bunches and challenges associated with their acceleration in a beam-driven accelerator (emittance preservation, beam loading compensation, chirp control, etc.).
  • Use of wakefields for beam control (dechirper, microbunch generation, etc.), radiation production, and diagnostics.
  • Progress toward the integrated design of beam-driven accelerators for linear-collider applications and future light source concepts.

The working group will include discussions on theoretical and numerical-simulation developments along with experiment results and plans.

WG5 – Beam Sources, Monitoring, and Control

Yine Sun (ANL), Samuel Barber (LBNL)

WG 5 will address the three subjects in its title:

  • Beam sources: Advanced accelerator and beam sources require and/or generate beams with unique characteristics, including femtosecond bunch lengths, high peak currents, high bunch charges, correlated and uncorrelated energy spreads, and position, pointing, and timing stability issues. This working group will examine the feasibility of meeting these requirements and beam properties.
  • Monitoring and diagnostics: Advanced accelerators carry a much larger burden in terms of diagnostics than conventional accelerators. The properties of these beams, the behavior of the accelerator structure, and the source driver (e.g., wakefield, RF, etc.) must be characterized. One of the goals in this area is a non-destructive single shot 6-d characterization of the particle beam phase space at various points along the accelerator. We will seek solutions for non-interceptive diagnostics to address some of the challenges of beam diagnostics.
  • Beam control and manipulation: Advanced accelerators are notorious for fluctuations in beam parameters such as energy, charge, pointing stability, bunch shape, etc. The capabilities of diagnostics to measure these beam properties have been continuously advancing, but there is also a great need to be able to use these measurements to improve and manipulate beam parameters, as well as shaping beams for use in a variety of scientific applications. We will examine the present advances and efforts in this quest.

We invite presentations, both theoretical and experimental, in the above areas as well as related subjects. We will discuss the state-of-the-art in these topics and we will try to identify the challenges that need to be addressed to further advance the field. Results of this assessment will be presented during the close out session of the workshop and in the written working group summary. Joint sessions with other WGs on the topics of beam generation, diagnostics and control may be scheduled.

WG6 – Laser-Plasma Acceleration of Ions

Lieselotte Obst-Huebl (LBNL), Mamiko Nishiuchi (National Institute for Quantum Science and Technology, Japan), Igor Pogorelsky (BNL)

Advanced ion beam sources based on interactions of ultra-intense laser pulses with over-dense plasmas are deemed to complement conventional ion accelerators by offering a reduced cost and higher compactness, in addition to a high dose per shot, flexible repetition rates and a variety of accelerated ion species. Ongoing advancements in ultra-high peak power lasers and computational techniques fuel progress in advanced ion acceleration, which is a research field rich with physical mechanisms to explore and a variety of high-demand applications ranging from cancer therapy to novel neutron and THz sources. Some applications, like studies of high-dose rate radiobiological effects and warm dense matter states, are already actively pursued in basic research settings.

We invite contributions to WG6 that present new results and initiatives of experimental, theoretical, computational and design studies in laser-driven ion acceleration including proton, light- and heavy-ion generation from solid and gas targets, plasma accelerator staging, progress towards higher ion beam energy and luminosity, beam transport and manipulation, diagnostics, secondary radiation and particle sources, as well as present and future applications.

Original, status and review papers are welcome.

WG7 – Radiation Generation and Advanced Concepts

John Palastro (University of Rochester), Julia Mikhailova (Princeton University)

Advanced light sources have opened new frontiers in radiation brilliance, tunability, power, and wavelength and are among the world’s most productive scientific instruments. Assessing the achievable performance of existing advanced laser and particle beam driven light sources, while continuing to innovate by exploring new radiation generation concepts is critical for the realization of advanced light-source applications.

We encourage participants to contribute work on laser or particle beam-driven radiation generation, particularly when the laser, beam, or radiation parameters are relevant to advanced-accelerators. Areas of interest include betatron radiation emitted by electron beams oscillating in a plasma-ion field, undulator radiation, progresses towards a plasma-based free-electron laser, Compton and Thomson scattering, coherent transition radiation, THz generation, Bremsstrahlung, VUV, x-ray, and high harmonic generation in plasmas, and plasma-based laser amplification. The generation of radiation with unique properties such as ultra-short pulses, spatiotemporal or orbital angular momentum structure, polarization control, multi-color radiation, and applications of these radiation sources is also of interest.

Finally, advanced concepts that enable improved laser or beam performance, particularly for radiation applications, are of interest. These include phase-space manipulation and cooling, space-time structuring, and novel configurations or architectures.

WG8 – Advanced Laser and Beam Technology and Facilities

Stephen Milton (Tau Systems), Marcus Babzien (BNL)

The primary focus of working group 8 will be the laser and beam technologies required for novel accelerators. Both laser-driven and beam-driven efforts will require orders of magnitude improvement to produce future particle colliders. Advancements in technologies and requirements for these future novel accelerators will be of primary importance. Many new facility and experimental capabilities are emerging for users world-wide. We would like to hear about how new experimental capabilities in these facilities will improve our data quality and understanding of the laser- and beam-driven accelerator physics. This can include new experimental, data acquisition and analysis techniques, new diagnostic and stabilization methods, monitoring of facility performance including feedback and machine learning applications, and lessons learned from facilities developing these new, never-before accessed parameter spaces.

Lasers play an important role in advanced accelerator research and technology, from driving novel accelerators — high peak and average power lasers for LWFA, hybrid plasma acceleration schemes, DLA, ion acceleration, vacuum acceleration — to tools as diagnostics for the specialized charged particle bunches produced by advanced accelerators and sources for the fs-level jitter synchronization that will be needed for future facilities. WG8 welcomes submissions on the technologies required to achieve the required laser parameters for all these goals. All proposed architectures are of interest, including improvements in beam quality, pulse fidelity, efficiency, stability, and robustness. We would like to discuss these advances in laser and beam drivers and the supporting technologies required to achieve them, with a focus on how these new technologies will affect the quality of the particle beams produced.