Figure 2.
Three-dimensional OSIRIS simulation for an LWFA stage with ionization injection. (a(i)) Electron density on the central x–z plane of the simulation during the injection process, at z = 0.05 mm. (a(ii)) Same quantities once the dopant section has been passed, at z = 0.76 mm. The electron densities of the plasma (grey) and the high levels of nitrogen (blue/yellow) are shown. Also the magnitude of the normalized vector potential of the laser is shown (orange/red). The dark grey line at the bottom shows the charge per unit of length of the injected electrons. (a(iii)) Longitudinal electric field, Ez, also at z = 0.76 mm. The red outline represents the on-axis values. (b(i)) Longitudinal phase space of the witness beam, and (b(ii)) Sliced values of the current (blue), relative energy spread (red) and normalized emittance in the x (dark grey), and y (light grey) planes. (c(i)) Evolution of the average longitudinal momentum of the beam (dark grey), the total relative energy spread (red), and the average sliced relative energy spread (dashed red), with the propagation distance. (c(ii)) Evolution of the projected normalized emittance of the beam in the x (dark grey), and y (light grey) planes. (Online version in colour.)