Table-Top Soft X-ray Ar+8 Lasers Excited By Capillary Z-Pinches

Abstract

The present study demonstrates Ar+8 laser operation without using any external low-current pre-ionization circuit. Instead, the pre-ionization of the argon gas was provided by automatic pre-ionization via the so-called gliding discharge on the internal surface of the capillary driven by the main excitation circuit. Such a technique considerably simplifies the laser device; the use of the relatively low voltage (200 kV) of the main excitation pulse allowed the use of a gas (SF6 or air at atmospheric pressure) as an electrical insulator in the Marx generator instead of the unpractical biodegradable transformer oil. The reduction of the voltage and current of the main excitation pulse also reduced the ablation of the electrodes and capillary walls increasing their lifetimes. The rest of the chapter is organized as follows. Section 2 describes the basic physical operation principles of Ar+8 lasers. The main physical processes in the laser medium (capillary z-pinch plasma) are described. The main plasma parameters, such as the temperature, density, length, diameter and homogeneity required for the saturated operation of the Ar+8 lasers are analyzed. The methods and techniques providing the experimental realization of the plasma parameters required for Ar+8 laser operation are described in section 3. The experimental results are also presented with a brief discussion of perspectives for future research.