Single-shot simulation at a column density of 68 × 1017 cm−2 near the n = 3 and n = 4 resonances
Figure 5. Single-shot simulation at a column density of 68 × 1017 cm−2 near the n = 3 and n = 4 resonances. The upper panel shows the simulated SASE wavelength profile (red), the transmission of the gas cell (black, same x-axis), the phase due to absorption (black, right-hand y-axis), and the transmitted wavelength profile (blue). The lower panel shows the time profile of the electric field before (red) and after (blue) the gas cell.
Using the third harmonic of the FEL radiation from the SPring-8 compact SASE (self-amplified stimulated emission) source SCSS we have studied the effects on SASE pulses with central wavelengths near 20 nm due to passage through a helium gas cell. The positions of zero ionization cross-section close to wavelengths corresponding to double-excitations allow operation as an efficient wavelength filter, with effectively 100% transmitted peak intensity until the Doppler-broadening limit is reached. We discuss how the time profile of the SASE pulses is affected, and discuss potential applications.