Figure 2
From: Positron acceleration in a hollow plasma channel up to TeV regime
Phase space portraits of the driver and the witness bunch (energy W versus co-propagating coordinate ξ = z − ct) (a–d) and corresponding energy spectra (e–h).
The snapshots are taken at propagation distances L = 50, 400, 750 and 1100 m. The positrons and protons are shown in blue and red, respectively.
