Characterization of broadband emission around 40 nm from potassium plasma

We characterize the emission spectra of a potassium plasma and its temporal behavior at 39 nm. To understanding the potassium spectral behavior without contamination effect, we use a laser-produced plasma to control the plasma parameters by changing the laser intensity and wavelength. Potassium ions produced strong broadband emission around 40 nm ranging from K3+ to K5+ ions at a time-averaged electron temperature of about 12 eV. Emission at 39 nm is caused during the recombining phase and it was reproduced by hydrodynamic simulation, which accounted for atomic processes. As the emission spectral behavior of the laser-produced potassium plasma XUV source is similar to that of the hollow cathode-mode discharge-produced plasma spectrum, it indicates that the emission from the discharge-produced plasma occurs in a region of high electron density close to 1020 cm-3.

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