Transverse Thomson and x-ray images of the plasma channel

Abstract

<p><strong>Figure 9.</strong> Transverse Thomson and x-ray images of the plasma channel. Data represent file 520/14 June 2012. The physical parameters are the following: 248 nm pulse energy 200 mJ, Kr plenum temperature <em>T</em> = 295 K, and Kr plenum pressure 185 psi. The centre of the nozzle is located at position <em>Z</em> = 0 mm. The arrows located at position <em>Z</em> = 1.25 mm in all panels indicate the position of the focal plane of the axial von Hámos spectrometer. (a) Thomson image of the electron density. A lateral extension is visible at <em>Z</em> 0 mm along with a narrow axial elongation well into the zone <em>Z</em> ≥ 0.5 mm. This axial extension is illustrated further in figure <a href="http://iopscience.iop.org/0953-4075/46/15/155601/article#jpb468344f10" target="_blank">10</a>. (b) Panel (a) represented as an isometric view. (c) The x-ray morphology of the plasma channel viewed transversely with the pinhole camera corresponding to the Thomson image shown in panel (a). The spatial region defined by <em>Z</em> ≥ 0.5 mm is completely dark. The shaded zone centred on <em>Z</em> = 1.25 mm indicates the depth-of-field of the axial von Hámos spectrometer.</p> <p><strong>Abstract</strong></p> <p>Experimental evidence demonstrating amplification on the Kr²⁶⁺ 3s→2p transition at λ 7.5 Å (~1652 eV) generated from a (Kr)<em>_n</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