Author: Larsen, K.
Paper Title Page
WEOZGD2
Status and Prospects for the Plasma-Driven Attosecond X-Ray (PAX) Experiment at FACET-II  
 
  • C. Emma, R.M. Hessami, K. Larsen, A. Marinelli, R. Robles
    SLAC, Menlo Park, California, USA
 
  Funding: This work was supported by the Department of Energy, Laboratory Directed Research and Development program at SLAC National Accelerator Laboratory, under contract DE-AC02- 76SF00515.
Plasma-driven light source development has recently made significant progress with the demonstration of plasma-FEL gain and the work of multiple facilities towards plasma-FEL development *. In this paper, we report on the status and prospects for one-such plasma-driven light source effort, the Plasma-driven Attosecond X-ray (PAX) experiment at FACET-II ** . This unique experimental thrust seeks to generate 100-attosecond long electron beams using plasma accelerators and use these beams as drivers for an attosecond X-ray source. This approach is motivated by the possibility to generate ultra-short high power attosecond X-ray pulses, as well as the order-of-magnitude increased tolerances of this method to emittance, energy spread and pointing jitter compared to a plasma-driven XFEL starting from noise. We present recent experimental developments in the process of demonstrating this concept at FACET-II and discuss potential extensions of this method to scale towards shorter wavelengths in the future.
* W. Wang et al Nature 595, 516 2021; R. Pompili Proc. of EAAC 2021; C. Emma et al High Power Laser Science and Engineering, 2021, Vol. 9, e57,
** C. Emma et al APL Photonics 6, 076107 2021
 
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WEPOTK064 Generating Sub-Femtosecond Electron Beams at Plasma Wakefield Accelerators 2217
 
  • R. Robles, C. Emma, R.M. Hessami, K. Larsen, A. Marinelli
    SLAC, Menlo Park, California, USA
 
  Funding: This work was supported by US Department of Energy Contracts No. DE-AC02-76SF00515 and by the DOE, Laboratory Directed Research and Development program at SLAC, under contract DE-AC02-76SF00515.
The Plasma-driven Attosecond X-ray source (PAX) project at FACET-II aims to produce attosecond EUV/soft x-ray pulses with milijoule-scale pulse energy via nearly coherent emission from pre-bunched electron beams. In the baseline approach*, a beam is generated using the density downramp injection scheme with a percent-per-micron chirp and 1e-4 scale slice energy spread. Subsequent compression yields a current spike of just 100 as duration which can emit 10 nm light nearly coherently due to its strong pre-bunching. In this work, we report simulation studies of a scheme to generate similarly short beams without relying on plasma injection. Instead, we utilize a high-charge beam generated at an RF photocathode, with its tail acting as the witness bunch for the wake. The witness develops a percent-per-micron chirp in the plasma which is then compressible downstream. The final bunch length demonstrated here is as short as 100 nm, and is limited primarily by emittance effects. The configurations studied in this work are available for experimental testing at existing PWFA facilities such as FACET-II.
*APL Photonics 6, 076107 (2021)
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-WEPOTK064  
About • Received ※ 08 June 2022 — Revised ※ 15 June 2022 — Accepted ※ 15 June 2022 — Issue date ※ 16 June 2022
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