The quality of electron beams produced from plasma-based accelerators, i.e., normalized brightness and energy spread, has made transformative progress in the past several decades in both simulation and experiment. Recently, full-scale particle-in-cell (PIC) simulations have shown that electron beams with unprecedented brightness (1020–1021 A=m2=rad2) and 0.1–1 MeVenergy spread can be produced through controlled injection in a slowly expanding bubble that arises when a particle beam or laser pulse propagates in density gradient, or when a particle beam self-focuses in uniform plasma or has a superluminal flying focus. However, in previous simulations of work on self-injection triggered by an evolving laser driver in a uniform plasma, the resulting beams did not exhibit comparable brightnesses and energy spreads. Here, we demonstrate through the use of large-scale high-fidelity PIC simulations that a slowly expanding bubble driven by a laser pulse in a uniform plasma can indeed produce self-injected electron beams with similar brightness and energy spreads as for an evolving bubble driven by an electron beam driver. We consider laser spot sizes roughly equal to the matched spot sizes in a uniform plasma and find that the evolution of the bubble occurs naturally through the evolution of the laser. The effects of the electron beam quality on the choice of physical as well as numerical parameters, e.g., grid sizes and field solvers used in the PIC simulations are presented. It is found that this original and simplest injection scheme can produce electron beams with beam quality exceeding that of the more recent concepts.
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This content will become publicly available on January 1, 2025
Characterization of meter-scale Bessel beams for plasma formation in a plasma wakefield accelerator
A large challenge with Plasma Wakefield Acceleration lies in creating a plasma with a profile and length that properly match the electron beam. Using a laser-ionized plasma source provides control in creating an appropriate plasma density ramp. Additionally, using a laser-ionized plasma allows for an accelerator to run at a higher repetition rate. At the Facility for Advanced Accelerator Experimental Tests, at SLAC National Accelerator Laboratory, we ionize hydrogen gas with a 225 mJ, 50 fs, 800 nm laser pulse that passes through an axicon lens, imparting a conical phase on the pulse that produces a focal spot with an intensity distribution described radially by a Bessel function. This paper overviews the diagnostic tests used to characterize and optimize the focal spot along the meter-long focus. In particular, we observe how wavefront aberrations in the laser pulse impact the peak intensity of the focal spot. Furthermore, we discuss the impact of nonlinear effects caused by a 6 mm, CaF2 vacuum window in the laser beam line.
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- Award ID(s):
- 2012549
- PAR ID:
- 10526588
- Editor(s):
- Pilat, Fulvia; Fischer, Wolfram; Saethre, Robert; Anisimov, Petr; Andrian, Ivan
- Publisher / Repository:
- JACoW Publishing
- Date Published:
- ISSN:
- 2673-5490
- ISBN:
- 978-3-95450-247-9
- Subject(s) / Keyword(s):
- Accelerator Physics mc6-beam-instrumentation-controls-feedback-and-operational-aspects - MC6: Beam Instrumentation, Controls, Feedback, and Operational Aspects MC6.T25 - MC6.T25 Lasers
- Format(s):
- Medium: X Size: 1865-1868 pages; 1.9 MB Other: PDF
- Size(s):
- 1865-1868 pages 1.9 MB
- Right(s):
- Creative Commons Attribution 4.0 International
- Sponsoring Org:
- National Science Foundation
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