Key diagnostic components showing the triple pinhole x-ray camera, the Thomson imaging system with the objective lens and periscope to direct the signal to the camera equipped with a 248 nm interference filter and functioning with a spatial resolution of ~22 µm, and the transverse von Hámos spectrometer enabling the recording of a spatially resolved Kr(L) spectrum along the axis of the channel with a spectral resolution of ~3 eV and a spatial resolution of ~50 µm

Figure 1. Key diagnostic components showing the triple pinhole x-ray camera, the Thomson imaging system with the objective lens and periscope to direct the signal to the camera equipped with a 248 nm interference filter and functioning with a spatial resolution of ~22 µm, and the transverse von Hámos spectrometer enabling the recording of a spatially resolved Kr(L) spectrum along the axis of the channel with a spectral resolution of ~3 eV and a spatial resolution of ~50 µm. The axial von Hámos spectrometer is located on the channel Z-axis. The incident 248 nm beam with a pulse rate of ~0.1 Hz and diameter of ~10 cm enters from the right and is focused by the off-axis parabolic mirror to the position of the Kr cluster target. The orifice of the 2.65 mm diameter sonic nozzle that furnishes the (Kr)n target with upward vertically directed flow is indicated. The single-pulse data from all four cameras are collected under computer control along with the 248 nm pulse energy, nozzle plenum pressure, and Kr gas temperature.

Abstract

Experimental evidence demonstrating amplification on the Kr26+ 3s→2p transition at λ 7.5 Å (~1652 eV) generated from a (Kr)n 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.