Fig. 3: 6D optimization of betatron X-ray source.

a Top panel shows the mean (normalized) X-ray yield for each burst (circles) with SE. The dashed line shows the model predicted maximum value of X-ray yield with the shaded region enclosing ±SD uncertainty. The lower panel shows the evolution of the input parameters representing the focal position of the laser pulse (f), the plasma electron density (n_e), the plasma source length (L_cell) and three orders of spectral phase (β⁽²⁾, β⁽³⁾, β⁽⁴⁾). b X-ray images from the initial and optimal bursts, where the signal for each pixel is the mean from the ten individual shots. The initial X-ray image is multiplied by 5, to make it visible on the same scale. c The projection of the measurements onto each 2D plane of the parameter space, colour coded by the normalized total X-ray counts.