Extreme ultraviolet absorption spectroscopy of a backlighted aluminum plasma

We show that a cold, dense laboratory plasma can be readily characterized by extreme ultraviolet absorption spectroscopy. The plasma is produced by irradiating a thin aluminum foil with a pulsed soft x‐ray source. The same source also provides a backlighting continuum for absorption spectroscopy. Time‐integrated L‐shell spectra obtained with a grazing incidence spectrograph show collisionally broadened absorption lines of A1 IV and A1 V. The spectra provide plasma temperature and electron density measurements of ≳12 eV and 0.6×1021 cm−3, respectively.