Ruxin Li

A simple in situ calibration technique for soft x‐ray film

A simple valid in situ relative intensity calibration technique for soft x‐ray film is described. This is based on film exposure measurements of the uniform line‐shaped distributed soft x‐ray monochromatic irradiation transmitted through a step‐wedge absorption filter. Fitting the calibration data with Henke’s semiempirical equation for thick‐emulsion film, the characteristic curves for Shanghai 5F soft x‐ray film without supercoat (SIOM‐5FW) have been obtained in the wavelength region from 50 to 80 A.

Space‐ and time‐resolved investigation of short wavelength x‐ray laser in Li‐like Ca ions

We have demonstrated the soft x‐ray amplification for lithium‐like Ca17+ 4f‐3d transition at 57.7 A with 900 ps, 1.05 μm drive laser pulse. The spatial distribution of the gain coefficient and temporal history of the lasing line emissions were also obtained.

Studies of Recombination X-Ray-Laser Gain and Gain-Medium Uniformity

The time evolution of the uniformity of the line-shaped X-ray-laser gain medium and the spatial characteristics of the recombination X-ray-laser gains of the Li-like ions are studied using long (∼900 ps) and short (∼100 ps) laser pulses.

Spot-focused laser-plasma toward large-scale, line-shaped, uniform monochromatic soft x-ray source

A simple way to obtain a large-scale, line-shape, uniform monochromatic soft x-ray source is described. Spot-focused laser-plasma of various materials serve as an original source, then a dispersion system (consisting of pre-optics and a flat-field concave grating) transforms the abundant line emission point source into a series of monochromatic line-shaped sources located on the spectrum focal plane of the concave grating. The intensity uniformity along the longitudinal direction and the monochromaticity of this kind of line source are treated carefully in this paper.

An alternative method for gain determination of recombination X-ray lasers

Abstract An improved method was proposed for gain determination of recombination X-ray lasers. The axial line intensity ratio of the lasing emission to an optically thin spontaneous emission is used to overcome the intensity fluctuations caused by shot-to-shot randomness in laser conditions. With this method, the gain of the Li-like Si 4f-3d lasers at 13.0 nm was measured, which is in agreement with theoretical simulations.

Space resolved spectrograph for laser induced plasma diagnostics

The detailed characteristic of a stigmatic grazing incidence grating spectrograph was investigated by a ray-tracing and spectroscopic experiments. As an example of application, some new physical result on the comparison of long-pulse and short-pulse laser driven recombining plasma are described.

Emission from line‐focused laser‐heated multi‐groove target

Line‐shaped plasma was produced by ablating plasma from multi‐groove Aluminum surface of a groove period of 100 μm, on which the direction of groove (50 μm in depth and 50 μm in width) is perpendicular to the focal line of 1.05 μm 120 ps (FWHM) heating laser. Comparison with the results of flat‐slab target, different spatial profiles of electron density and temperature and line emission intensity were found. Enhancement of on‐axis emission of candidate lasing line of Al10+which maybe originate from enhanced GL value were observed.

Development of short-wavelength coherent XUV light sources at SIOFM

Recent progress on the development of short-wavelength coherent XUV light sources at SIOFM is presented, including the space- and time-resolved observation of short-wavelength lasing by lithium-like Si11+, Ca17+, and Ti19+ ions and H-like F8+ ion, and the theoretical design for new approaches, such as controlled expansion cooling, x-ray pumping and strongly radiative cooling.

Time and space resolved studies of recombination x-ray lasers

Abstract A novel experimental technique of time- and space-resolved X-ray diagnostics has been developed by coupling a stigmatic flatfield grating spectrometer to a soft X-ray streak camera to study the dynamics of recombination X-ray lasers. Time and space characteristics of Li-like Si X-ray lasers have been investigated and some interesting results have been obtained. Preliminary results with CaF2 target are given.

Recent progress on shorter wavelength recombination X‐ray laser research at SIOFM

We will report recent progress on shorter wavelength recombination X‐ray laser research at SIOFM, including the observation of lasing at 46.8 A of the lithium‐like Ti19+ 4f‐3d transition, which was conducted at LF12 laser facility of SIOFM with Ti slab targets driven by an about 110 ps‐duration FWHM quasi‐Gaussian pulse (λ=1.05 μm). Comparison of long‐pulse (∼900 ps) and short pulse (∼110) driving Li‐like Si and Ca ions and H‐like F ion recombination X‐ray lasers will also be presented.