X-ray transverse image of the channel and axial Kr(L) spectrum recorded with a mica von Hámos spectrograph

<p><strong>Figure 8.</strong> X-ray transverse image of the channel and axial Kr(L) spectrum recorded with a mica von Hámos spectrograph. Single-pulse data correspond to file 677/18 May 2012. (a) Transverse x-ray pinhole camera image of plasma channel morphology that gives an upper bound for the source size Δ<sub>Ch</sub>  150 µm. The spatial resolution of the camera is estimated to be ~50 µm. (b) Two-dimensional Kr(L) axial spectrum recorded with a mica von Hámos spectrometer that gives an estimated source size of Δ<sub>Sp</sub>  150 µm, a value that matches the corresponding width of the x-ray image in panel (a). (c) Isometric view of the axial von Hámos recording showing the spectral peak designated by A with a width δ<sub>λ,1</sub>  3 eV for the Kr<sup>26+</sup> 3s → 2p transition at λ 7.5 Å that is also represented in figure <a href="http://iopscience.iop.org/0953-4075/46/15/155601/article#jpb468344f7" target="_blank">7</a>(a). (d) Magnified cross section of the spectral peak A shown in panel (c) that illustrates its spatial width (FWHM) Δ<sub>Sp</sub>  135 µm. This source size is within one pixel of the spatial diameters estimated in panels (a) and (b).</p> <p><strong>Abstract</strong></p> <p>Experimental evidence demonstrating amplification on the Kr<sup>26+</sup> 3s→2p transition at λ 7.5 Å (~1652 eV) generated from a (Kr)<em><sub>n</sub></em> cluster medium in a self-trapped plasma channel produced with 248 nm femtosecond pulses is presented. The x-ray beam produced had a spectral width of ~3 eV and a corresponding beam diameter of ~150 µm, properties that were simultaneously determined by a two-dimensional x-ray spectral image formed with an axially placed von Hámos spectrometer and a matching Thomson image of the spatial electron density generated by the x-ray propagation.</p>