Figure 3. Influence on the electron beam divergence of the peak electron density in the second gas jet (the laser-plasma lens).

The divergence was measured for an electron energy of 270 MeV. The distance between the two stages is L=2.3 mm. Data points were averaged over at least 11 shots; the vertical error bars correspond to the s.e.m. and the horizontal bar correspond to the precision on the backing pressure. The analysis of the interferograms leads to an additional systematic error on the density of ±5%.