Soft X-Ray Emission from a Laser-Produced Carbon Plasma

Abstract

Under specific conditions laser produced plasmas can be created which emit radiation only in a few well isolated spectral lines in the soft X-ray region. Using a Nd:YAG laser system with a pulse length of 170 ps and a pulse energy of 215 mJ in a focus with a diameter of 50 μm on a plane carbon target, a plasma was created emitting mainly the resonance series of hydrogen- and heliumlike carbon ions. The emission lies in the region between 300 and 500 eV and is of special interest to X-ray microscopy as it lies within the “water window”. For the C V line at 308 eV the contrast ratio between the emission in the spectral line and in the continuum adjacent to that line is better than 500. The absolute emission in this line is 5.5×10¹² photons/sr per pulse. The reproducibility of the radiation emission is about 15%.