High-power-density capillary discharge plasma columns for shorter wavelength discharge-pumped soft-x-ray lasers

Abstract

We report the generation of plasma columns in gas-filled capillary channels using discharge excitation powers that exceed those of previous studies by one to two orders of magnitude. Current pulses up to 200 kA and 10-90 % rise time of ϳ10 ns ͑current increase rate ϳ1.5ϫ1013 A/s͒ were utilized to excite plasmas in 3.3 and 4 mm diameter channels. Time resolved soft-x-ray spectra and pinhole images of the plasma were obtained. The experimental data and its comparison with model computations suggest that dense argon plasma columns 300 m in diameter with electron temperatures Ͼ250 eV have been obtained. These characteristics make these plasmas of interest for extending discharge-pumped lasers to shorter wavelengths.

Identification ofn= 4, Δn= 0 Transitions in the Spectra of Nickel-like Cadmium Ions from a Capillary Discharge Plasma Column

“…Transitions to the ground state 3d 10 were observed at low resolution in [5] and surveyed theoretically by MCDF [6], parametric potential [7] and RMBPT methods [8]. At wavelengths longer than 13.2 nm, non-lasing lines have been observed from laser produced plasmas (LPP).…”

“…In this work we report the identification of 53 transitions corresponding to Ni-like Cd ions based on spectra obtained from cadmium plasma columns generated using a fast capillary discharge. The spectroscopy of ions with such a high degree of ionization in discharge-created plasmas is made possible by a new type of fast capillary discharge that operates at peak currents of up to 200 kA and current risetimes exceeding 1:5 Â 10 13 A=s [10]. Relative to laser-created plasmas these capillary discharge plasmas have a lower electron density.…”

Extreme Degree of Ionization in Homogenous Micro-Capillary Plasma Columns Heated by Ultrafast Current Pulses

“…This intrinsic limitation of the kinetic conversion scheme makes it difficult to extend it to applications such as the development of sub-10 nm wavelength lasers, which require axially uniform plasma columns that are significantly denser and hotter (e.g. 26 times ionized Xe [14,15] and electron temperatures of ~400 eV). Such scaling is particularly challenging for high-Z plasmas where radiative cooling is large [5].…”

Modeling of Capillary Discharge Plasma for X-ray lasers, XUV Lithography and other Applications

“…Substantial experimental and theoretical efforts are now devoted to extend this kind of XRL to shorter wavelengths. The RADEX simulations and spectroscopic diagnostics experiments of plasma indicate that the electron density N e > 10 20 cm -3 and temperature T e ~ 200-400 eV at higher currents ~150-200 kA can be achieved in capillary discharge of high-Z plasma [2,11]. At such temperatures and densities the collisional XRL scheme on Ni-like ions can work particularly well.…”

“…One of their variants, the capillary discharges, attracted attention of plasma physics researchers for almost two decades. It has been used for hot dense plasma formation and x-ray lasers [1,2], for transportation of laser beams and XUV radiation generation in x-ray lithography [3,4], for basic Z-pinch research and some others. The combination of efficiency, simplicity and low cost of capillary electrical discharges allowed to scale capillary x-ray lasers to table-top dimensions.…”