Nickel-like Silver X-ray Laser Research Articles

Evaluation of fast EUV scintillator using 13.9 nm x-ray laser

The nickel-like silver x-ray laser with the wavelength of 13.9 nm is used as a high power EUV excitation source to evaluate a scintillator for EUV lithography. The time resolved spectrum of zinc oxide exciton emission at around 380 nm was observed. The determined fluorescence lifetime of 1.1 ns is sufficiently short for characterizing EUV lithography light sources having a few nanoseconds duration. It is also shown that the x-ray laser is an excellent tool for spectroscopic characterization of materials intended for next-generation lithography applications.

Opacity Measurements of a Hot Iron Plasma Using an X-Ray Laser

The temporal evolution of the opacity of an iron plasma at high temperature (30-350 eV) and high density (0.001-0.2 g cm-3) has been measured using a nickel-like silver x-ray laser at 13.9 nm. The hot dense iron plasma was created in a thin (50 nm) iron layer buried 80 nm below the surface in a plastic target that was heated using a separate 80 ps pulse of 6-9 J, focused to a 100 microm diameter spot. The experimental opacities are compared with opacities evaluated from plasma conditions predicted using a fluid and atomic physics code.

High-Precision Measurement of the Wavelength of a Nickel-like Silver X-ray Laser

We conducted high-precision measurements of the wavelength of a 4d1S0→4p1P1 line of a nickel-like silver X-ray laser. The Lyman series lines of hydrogen-like helium ions emitted from low-density plasmas were used as wavelength references, and the wavelength of the X-ray laser line was determined to be 13.887 nm (±0.002 nm). The experimental results were compared with Multiconfiguration Dirac–Fock calculations and were found to agree with theoretical wavelengths.

Transverse spatial coherence of a transient nickellike silver soft-x-ray laser pumped by a single picosecond laser pulse.

The degree of spatial coherence in the direction perpendicular to the target surface is reported for a transient nickellike silver x-ray laser at 13.9 nm. An x-ray laser plasma column was produced by irradiating a slab silver target with a single shaped picosecond laser pulse with energy less than 3 J. Young's double-slit method was applied to measure the fringe visibility as a function of the slit separation for different target lengths. The diameter of the equivalent incoherent source and the coherence radius of the output radiation were determined as well.

Development of a pumping laser system for x-ray laser research.

A two-beam chirped-pulse-amplification Nd:glass laser system dedicated to x-ray laser research is described. Each beam provides an output energy of 20 J with a typical pulse duration of 1.3 ps. A prepulse of variable duration is generated by use of a novel, to our knowledge, optical system. A reflection optical system, comprised of an off-axis parabolic mirror and a spherical mirror, produces a line focus with 6-mm length and 165-microm width without chromatic aberration. By use of this pumping laser system, the nickel-like silver x-ray laser at a wavelength of 13.9 nm has been demonstrated.

Modeling of the transient nickellike silver x-ray laser

Recent high-temporal-resolution nickellike x-ray laser experiments have yielded important insights into the output characteristics of picosecond-pumped x-ray lasers. However, current experimental observations do not fully explain the plasma dynamics, which is critical to gain generation within the x-ray laser medium. A numerical study of the nickellike silver x-ray laser has therefore been undertaken to complement our experimental results in an attempt to further our understanding of the processes at work in yielding the observed x-ray laser output. High gain coefficients existing with picosecond lifetimes are predicted, which is consistent with the short x-ray laser durations experimentally observed. The late onset of the continuum emission relative to the temporal peak of the x-ray laser output is explained as a sign of high electron density evolution near the target surface.

Characterization of a transient Ni-like Ag X-ray laser under two-color irradiation

By frequency-doubling the long pre-forming pulse in the now well-known transient collisional excitation (TCE) scheme, a two-color (2ω/1ω) pumping of the nickel-like silver x-ray laser (XRL) has been investigated both experimentally and theoretically. The angular XRL characteristics have been studied and compared to standard (1ω/1ω) and inverse 2-color (1ω/2ω) irradiations. Through a statistical treatment of the recorded data, a significant reduction of the beam divergence has then been noticed. Moreover, the influence of the required traveling wave irradiation on the amplification duration has been checked, the observed shortening being explained by either a simple propagation model or more sophisticated simulations.

Near-field spatial imaging of a Ni-like Ag 140-Å x-ray laser

We measure the two-dimensional, near-field spatial distribution of a 140-\AA{} nickel-like silver x-ray laser at the output aperture with high magnification using a curved multilayer x-ray mirror to image the output onto an x-ray charge-coupled device camera. Lasing is created by illuminating silver slab targets with a pair of 75 ps laser pulses separated by 2.2 nsec from the Vulcan laser. The two-dimensional, high-resolution, spatial image shows the x-ray laser source size and its position relative to the target surface. A dramatic change in both the position and source size are observed for the refraction compensating curved target as compared with the flat targets.