Soft X-ray Radiation from Nitrogen Z-pinch Plasma Produced by Capillary Discharge

Abstract

Characteristics of soft X-ray radiation from nitrogen filled Z-pinch plasma columns energized by capillary discharge are reported in order to evaluate optimum plasma parameters for an H-like N recombination pumped soft X-ray laser, wavelength of which is 13.4 nm emitted by quantum transition from n=3 to n=2. The discharge system used in this experiment consists of a 3-stage Marx generator, a step-up transformer and a 3-nF water capacitor. Soft X-ray radiation from Z-pinch nitrogen plasma was measured by using a transmission grating spectrometer with a CCD array detector. Multiply-ionized ions up to N VII were confirmed to exist, and existence of N VIII was anticipated. This suggests that a plasma temperature at the pinch time is the order of 100 eV and might reaches over 150 eV. From these experimental results, plasma parameters and the discharge current required for realizing an H-like N recombination soft X-ray laser were estimated.