Speaker
Description
Laser-plasma accelerators (LPAs) of cm length, driven by petawatt lasers, now produce quasi-monoenergetic electron bunches of ~ 10 GeV in energy [1, 2]. New generations of experiments in emerging multi-PW facilities are expected to reach far greater energies, e.g., simulations show ~100GeV energy gain using 500J laser pulses in a single sub-meter stage[3, 4]. A new suite of diagnostics that match the compactness of the accelerators, without compromising accuracy and affordability, is desired. We report the design and performance of a compact magnetic spectrometer tailored to unique characteristics of quasi-monoenergetic, multi-GeV electron bunches from petawatt-laser-driven wakefield accelerators: mrad-level shot-to-shot pointing fluctuations, co-generation of betatron X-rays and of background electrons with a broad energy spectrum. The spectrometer replaces the first screen of a standard two-screen spectrometer with an array of thin, precisely-located, high-Z wires distributed throughout, and perpendicular to, the magnet’s dispersion plane. The thin, sharply-bounded shadows that they cast on betatron X-ray and electron signals enable determination of > 10 GeV electron energies and launch angles with few-% precision using a ∼ 1 T dipole magnetic field of ∼ 10 cm dimensions. Perturbations to the electron signals caused by hybrid acceleration mechanisms or inserted foils are also shown to be resolvable.
1. A. J. Gonsalves, K. Nakamura, J. Daniels, et al., Petawatt laser guiding and electron beam acceleration to 8 GeV in a laser-heated capillary discharge waveguide, Phys. Rev. Lett. 122, 084801 (2019).
2. C. Aniculaesei, T. Ha, S. Yoffe, et al., The acceleration of a high-charge electron bunch to 10 GeV in a 10-cm nanoparticle-assisted wakefield accelerator, Matter Radiat. Extremes 9.
3. K. G. Miller, J. R. Pierce, et al., Dephasingless laser wakefield acceleration in the bubble regime, Scientific Reports, Vol. 13, Iss. 1, (2023): 21306. DOI:10.1038/s41598-023-48249-4
4. J. L. Shaw, et al., 100-GeV Electron Beam via a Flying-Focus-Driven Laser-Plasma Accelerator, ArXiv: arXiv:2505.00157 (2025)
| Working group | WG5 |
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