Fig. 1: The concept of bunched beam generation from density downramp injection in PBA (not to scale). | Nature Communications

Fig. 1: The concept of bunched beam generation from density downramp injection in PBA (not to scale).

From: Generation of ultrahigh-brightness pre-bunched beams from a plasma cathode for X-ray free-electron lasers

Fig. 1

a A plasma with a density downramp (red line) is set at t = 0. Two linearly polarized laser pulses propagate from the two ends of the plasma towards its center and their overlap creates a density modulation with period λL/2 (black line). A properly delayed electron beam driver is incident on the plasma from the left to excite a blowout wake (as shown in the upper inset) and inject electrons only at half of the density modulation period (green dots) and they are mapped to discrete axial positions with period λb after injection (as shown in the lower inset). b The modulation of the phase velocity of position Ez = 0 with kp0ξ ≈ 4.

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