Kelly Kanizay

Dense plasma diagnostics with an amplitude-division soft-x-ray laser interferometer based on diffraction gratings

We report the demonstration of an amplitude-division soft-x-ray interferometer that can be used to generate high-contrast interferograms at the wavelength of any of the saturated soft-x-ray lasers (5.6-46.9 nm) that are available at present. The interferometer, which utilizes grazing-incidence diffraction gratings as beam splitters in a modified Mach-Zehnder configuration, was used in combination with a tabletop 46.9-nm laser to probe a large-scale (~2.7-mm-long) laser-created plasma.

Soft-x-ray laser interferometry of a plasma with a tabletop laser and a Lloyd's mirror.

We report what is believed to be the first demonstration of soft-x-ray interferometry of a plasma with a tabletop soft-x-ray laser. A Lloyds mirror interferometer was used in combination with a very compact lambda = 46.9 nm capillary-discharge-pumped laser to map the electron density in the cathode region of a pinch plasma.

Capillary discharge tabletop soft X-ray lasers reach new wavelengths and applications

Abstract For many years, researchers have envisioned the development of compact high repetition rate tabletop soft X-ray lasers that could be routinely used in application in numerous disciplines. With demonstrated average powers of several mW and mJ-level pulse energy at 46.9 nm, capillary discharge-pumped lasers are the first compact lasers to reach this goal. In this paper we summarize the development status of high repetition rate tabletop soft X-ray lasers based on capillary discharge excitation, and give examples of their successful use in several applications. Results of the use of a capillary discharge pumped 46.9 nm laser in dense plasma interferometry, soft X-ray reflectometry for the determination of optical constants, and laser ablation are described. The observation of lasing at 53 nm line in Ne-like Cl with output pulse energy up to 10 μ J is also reported.

Dense plasma diagnostics with an amplitude division soft X-ray laser interferometer based on diffraction gratings

We report the demonstration of an amplitude-division soft-x-ray interferometer that can be used to generate high-contrast interferograms at the wavelength of any of the saturated soft-x-ray lasers (5.6-46.9 nm) that are available at present. The interferometer, which utilizes grazing-incidence diffraction gratings as beam splitters in a modified Mach-Zehnder configuration, was used in combination with a tabletop 46.9-nm laser to probe a large-scale (~2.7-mm-long) laser-created plasma.

Soft x-ray laser interferometer used for dense plasma diagnostics

Laser interferometry allows the recording of the electron density in a great variety of plasmas. However, the absorption and refraction imposes a limitation to the maximum density, plasma size and plasma gradient that can be measured with this technique. The development of compact soft x-ray laser sources gives the opportunity to extend the limits of plasma interferometry, probing plasmas with high densities and steep gradients. We present results of plasma interferometry using an amplitude division interferometer and a table top soft x-ray laser. The interferometer is a modified Mach-Zehnder configuration with diffraction gratings used as beam splitters. The soft x-ray laser is a 46.9 nm capillary discharge table-top laser. The set up was used to probe a laser-created plasma with a temporal resolution of approximately 1 ns and densities up to 6 1020 cm-3.

Plasma diagnostics with a tabletop soft x-ray laser

We discuss the first demonstrations of plasma diagnostics using a tabletop soft x-ray laser. A very compact capillary discharge pumped Ne-like Ar laser operating 46.9 nm was used to perform shadowgraphy and interferometry experiments in discharge-created discharge plasma waveguide. In a second set of experiments we took advantage of the good spatial coherence of the capillary discharge laser to perform soft x-ray interferometry measurements. In a first experiment the laser was used in combination with a simple wavefront division interferometer based on Lloyds mirror to map the electron density distribution in the cathode region of a pinch discharge. In our most recent experiment we used an amplitude division interferometer, which utilizes diffraction grating as beam splitters, to probe a large scale laser-created plasma. Both interferometer schemes can be adapted to operate at the wavelength corresponding to any of the presently available saturated soft x-ray lasers.

Laser ablation and plasma interferometry with a tabletop soft x-ray laser

We report the first study of laser ablation and the demonstration of plasma interferometry with a tabletop soft x-ray laser. A capillary discharge pumped Ne-like Ar laser (46.9 nm) was focused using multilayer optics to significantly exceed the energy density necessary for the ablation of metals. Ablation in brass, stainless steel and aluminum samples is reported. The ablation patterns on brass were used in combination with ray tracing computations to characterize the focused soft x-ray laser beam. The radiation intensity within the 2 micrometer diameter central region of the focal spot is estimated to be approximately 1011 W/cm2, with an energy density of approximately 100 J/cm2. In a separate experiment we performed soft x-ray interferometry of a laser-created plasma using a table-top capillary discharge laser operating at 46.9 nm in combination with a novel amplitude division interferometer. The soft x-ray interferometer utilizes diffraction gratings as beam splitters in a Mach-Zehnder configuration to generate high contrast interferograms over a large field of view. This table-top system was used to probe a large-scale (3 mm long) plasma created by a Nd:YAG laser. The short wavelength of the probe laser has allowed mapping of the electron density in plasma regions with density gradients steeper than those that could be probed with the fourth harmonic of Nd:YAG for a plasma of this length.

Plasma probing with a table-top soft X-ray laser

Summary form only given. Due to their short wavelength, high brightness, and good spatial coherence soft X-ray lasers are excellent sources for the diagnostics of dense plasmas. We report the demonstration of plasma imaging and interferometry using a very compact table-top soft X-ray laser. A capillary discharge pumped 46.9 nm laser was used to obtain a sequence of high resolution shadowgrams of the plasma of a microcapillary discharge (380 /spl mu/m diameter, 8 mm long evacuated channel in polyacetal excited by a /spl sim/1.5 kA peak amplitude current pulse of 155 ns duration). The plasma was illuminated on-axis with the soft X-ray laser, and was imaged with 24/spl times/ magnification into an MCP/CCD detector using a 60 cm radius of curvature concave mirror coated with an iridium film. The plasma is observed to rapidly evolve from a nonuniform plasma into a remarkably uniform plasma column with minimum density on axis. These measured plasma characteristics confirm the excellent properties of these discharges as waveguides for laser radiation.

Plasma diagnostics using a tabletop soft x-ray laser: demonstration of shadowgraphy and interferometry using a Lloyd's mirror

We report the first demonstration of plasma imaging and interferometry using a tabletop soft x-ray laser. A very compact capillary discharge Ne-like Ar laser operating at 46.9 nm was used as a backlighter to study the evolution of the plasma of a micro-capillary discharge. The resulting series of shadowgrams show the plasma created by ablation of the walls of the evacuated micro-capillary rapidly evolves from a non-uniform initial state into a symmetric column with minimum density on axis. In a second experiment we took advantage of the good spatial coherence of the capillary discharge laser to perform interferometry measurements in the plasma of a pinch discharge. In this experiment the laser was used in combination with a wavefront division interferometer based on Lloyds mirror to map the electron density distribution in the cathode region of the discharge.

Demonstration of an amplitude-division soft x-ray interferometer for plasma diagnostics based on diffraction gratings

We have performed soft x-ray interferometry of a laser- created plasma using a novel amplitude division interferometer in combination with a tabletop capillary discharge laser operating at 46.9 nm. The soft x-ray interferometer utilizes diffraction gratings as beam splitters in a Mach-Zehnder configuration to generate high contrast interferograms over a large field of view. An advantage of this interferometer scheme is that it can be used at any of the wavelengths covered by presently available soft x-ray lasers. This table-top system was used to probe a large scale (approximately 3 mm long) plasma crated by a Nd:YAG laser. The short wavelength of the probe laser has allowed mapping of the electron density in plasma regions with density gradients stepper than those that could be probed with the fourth harmonic of Nd:YAG for a plasma of this length.