Figure 1

Schematic representation of the experimental set up. The output of the table top soft x ray (SXR) capillary laser is aligned with the axis of the bimirror interferometer using two multilayer mirrors that also contribute to filter off-band plasma radiation. The wave-front-division interferometer produces two beams that interfere onto a CCD. The inset shows the doughnut shape of the far-field profile of the laser beam recorded using a CCD. The size of the detector did not allow the recording of the entire beam.Reuse & Permissions

Figure 2

(a) Typical interferogram corresponding to the zero-path-length difference in the interferometer. The interferogram corresponds to a capillary discharge plasma column 21 cm in length. (b) Line representation of the interferogram computed from the region within the box in (a).Reuse & Permissions

Figure 3

Visibilities as a function of optical path difference for a capillary discharge plasma column 36 cm in length. The insets are interferograms that illustrate the deterioration of the fringe visibility with increased path difference due to finite temporal coherence. The line is a Gaussian fit to the data.Reuse & Permissions

Figure 4

(a) Measured laser output intensity as a function of capillary discharge plasma column length. Gain saturation is observed to occur for a plasma column length of ∼24 cm. (b) Measured laser linewidth as a function of discharge plasma column length. Five independent measurements of the linewidth were averaged for each capillary length. The error bars were selected to include all measurements. The lines are the results of simulations for the plasma conditions discussed in the text, assuming ion temperatures of 100, 87, and 70 eV from top to bottom, respectively. The computations take into consideration collisional redistribution. (c) The lines show the computed variation of the linewidth neglecting (full line) and including (dashed lines) collisional redistribution. The denser dashed line was computed using the ion-ion collision time of Lee and More and the other using a collision time determined by a molecular dynamics computation [32]. The plasma parameters are those described in the text and the ion temperature is 87 eV.Reuse & Permissions