Figure 4. The brightness and flux of the laser-driven source at current and proposed repetition rates compare favourably to existing microfocus sources:

(a) Given the measured fluctuation in photon number and source size, the 1σ contour of expected brightness is plotted in the brightness-spot size plane, plotted in units of photons per second per mm² of source area per mrad² of solid angle. Experimental data from microfocus sources are plotted as points, adapted from³⁷,³⁸. The solid line represents the simulated upper limit of a tungsten anode, using measured anode melting points³⁹ and simulated spectra⁴⁰. The number of photons is integrated over energies 10 keV < E_γ < 100 keV. (b) Accounting for the x-ray spot size, the brightness data are plotted as an average photon flux.