Streaked Spectrometry Using Multilayer X-Ray Interference mirrors to investigate Energy Transport in Laser Plasma Applications

Transport of energy in laser‐produced plasmas is scrutinized by devising spectrally and temporally identifiable characteristics in the x‐ray emission history which identify the heat‐front position at various times in the heating process. Measurements of the relative turn‐on times of these characteristics show the rate of energy transport between various points. These measurements can in turn constrain models of energy transport phenomena. We are time‐resolving spectrally distinguishable subkilovolt x‐ray emissions from different layers of a disk target to examine the transport rate of energy into the target. A similar technique is used to measure the lateral expansion rate of the plasma spot. A soft x‐ray streak camera with 15‐psec temporal resolution is used to make the temporal measurements. Spectral discrimination of the incident signal is provided by multilayer x‐ray interference mirrors. These synthetic x‐ray crystals have been characterized for reflectivity and bandwidth and exhibit resolutions E/ΔE of 10 to 90.