Figure 4. QuickPIC simulation at P=16 Torr.

Simulated beam electron density (a), plasma electron density (b) and longitudinal electric field E_z (c) at z=0, the location where the beam reaches its minimum transverse size in vacuum. (d) Evolution of the x and y beam sizes (r.m.s. values with 10% cut) of a slice of the bunch located at ξ=z−ct=−10 μm for propagation through a plasma (solid lines) and for propagation in vacuum (dashed lines). This slice is inside the blowout region when plasma is present. (e) Evolution of the longitudinal on-axis electric field E_z during beam propagation through the argon gas volume. The three different regions are described in the text.