Speaker
Description
Plasma-accelerated electrons often develop percent-level time-correlated energy spread (''chirp") because the longitudinal accelerating-field changes across the bunch. Existing approaches to dechirping typically require precise tailoring of the density profile of the plasma or the injected bunch, or the insertion of chirp-control devices downstream of the wake. Here, using particle-in-cell simulations, we identify a dechirping mechanism that relies only on the natural shortening of a wake as its pump depletes, causing the on-axis field slope across the accelerating bunch to reverse sign and compensate the chirp. The mechanism operates over a broad range of plasma densities and injected beam charges and profiles. We observe reduction of energy spread $\sigma_E/E$ of an externally injected electron bunch from $\sim$1% at injection (50MeV) to a minimum of $\sim$0.25%, with the bunch reaching $\sim$650MeV at the dechirped minimum. We will discuss how the choice of drive pulse wavelength, plasma density, and injection mechanism influences the effectiveness of this de-chirping mechanism.
| Working group | WG5 |
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