Elliptical spectrograph/gated microchannel‐plate detector for time‐resolved spectral measurements in the x‐ray region

Time‐resolved measurements from an elliptical crystal spectrograph are used to diagnose x‐ray laser experiments on a gas puff Z pinch. The elliptical spectrograph (1.2‐m working distance, eccentricity 0.9586) observes the 1‐keV region, covering a range of λ/2d = 0.5 to 0.9. A thin filter (0.2 μm Al on 2 μm Kimfol) stretched across the spectrograph exit slit acts as a low‐energy x‐ray cutoff and as a vacuum window, allowing the detector to be at high vacuum regardless of the pressure in the experimental chamber. The detector consists of a seven‐frame microchannel‐plate intensifier system. A pulser is used to gate each of seven striplines on the microchannel plate, providing nanosecond resolution. With this instrument we are able to measure the pump radiation from the imploding plasma (Ne or Ar) and converter layer (Al), and to study the lasant ionization state (Ne‐like Ni or Cu).