3D rendering of the EPiC diagnostic. The plasma x-ray source is multiply imaged out onto a large area CCD detector by an array of several pinholes (PHA) (not in scale in the figure). The CCD detector is forced to operate in the single-photon mode. Typical source-to-PHA distances are of a few centimeters and typical PHA-to-CCD distances range from a few tens of centimeters up to a few meters. The CCD detector can be placed, if needed, into a separate vacuum chamber with respect to the main one, provided that suitable x-ray windows are employed. The lower inset shows a scanning electron microscope image of a homemade pinhole array, drilled onto a 100 μm thick substrate (see text). The upper inset shows a typical acquired image; the “single-photon” images from the different pinholes are clearly visible (the brightest spot at the center was produced by a great diameter (100 μm) pinhole and was used for alignment purposes).
Simulated shape of a Gaussian plasma x-ray source imaged out at 10 keV using a 200 μm pitch, 10 × 10 pinholes array drilled onto a 100 μm thick Pt substrate. Each pinhole is supposed to have a diameter of 10 μm. Three cases corresponding to different source FWHMs are shown, which clarify the effect of a source size comparable to the array pitch: (a) 10 μm, (b) 100 μm, and (c) 150 μm. As one goes from (a) to (c), the useful window (see Eq. (2)) does not accommodate the source image and also overlapping effects start playing a role.
Layout of the experimental setup in a recent experiment carried out at RAL. The target was irradiated by two opposite sides. The overall size of the main vacuum chamber is 2 × 4 m2. The EPiC is highlighted by the blue box visible at the bottom of the figure.
X-ray spectrum retrieved using the EPiC in the RAL experiment. The images of the x-ray source in the two photon energy ranges identified by the vertical lines are shown in Figure 5.
X-ray source as retrieved by the EPiC at the Ti Heα energy (left) and at higher energy (>20 keV) (right) in the RAL experiment. The corresponding energy intervals are also highlighted in Figure 4 by the blue (left image) and purple (right image) vertical lines. The overall size of the images shown is 67.5 × 67.5 μm2.
X-ray source as retrieved by the EPiC at the Ti Kα energy (left) and at higher energy (>10 keV) (right) in the PALS experiment. The overall size of the images shown is 81 × 81 μm2.
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