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A simple XUV transmission grating spectrograph operating in the wavelength range 3-90 Å with sub-ångström resolution without using any XUV imaging optics is described. This is based on a free-standing gold microstructure grating of 2000 Å period in normal incidence geometry. A spectral resolution of 0.6 Å is obtained by optimizing the slit aperture, the source-to-grating distance and the grating-to-detector distance. Electron temperatures deduced from analysis of the spectrum of a laser-produced magnesium plasma using a plasma spectroscopic code are consistent with theoretical considerations. The spectral range can be extended to higher wavelengths by using a larger detector. The simple geometry and ease of operation of the spectrograph should make it useful in many experiments such as those involving plasma-based XUV lasers and odd-harmonic generation in the XUV spectral region using ultra-short laser pulses.

A comparative experimental study of soft x-ray emission from laser-irradiated Au–Cu mix-Z targets of different atomic compositions has been performed. Plasma was produced from planar targets using second-harmonic laser pulses from an Nd:glass laser at a focused intensity of ∼1013 W cm−2. Radiation intensity in the spectral region ∼15–150 Å and integrated x-ray yield for mix-Z target were observed to be higher than those for individual elements. The maximum conversion occurred for an atomic composition of Au 0.43–Cu 0.57. These observations are consistent with the variation of Rosseland mean opacity with atomic composition calculated using a screened hydrogenic average atom model.

Articles you may be interested inA high-resolution imaging x-ray crystal spectrometer for high energy density plasmasa) Rev. Sci. Instrum. 85, 11E606 (2014); 10.1063/1.4891053 Upgrades of imaging x-ray crystal spectrometers for high-resolution and high-temperature plasma diagnostics on EASTa) Rev. Sci. Instrum. 85, 11E406 (2014); 10.1063/1.4886387 Upgrades of the high resolution imaging x-ray crystal spectrometers on experimental advanced superconducting tokamaka) Rev. Sci. Instrum. 83, 10E130 (2012); 10.1063/1.4738652 Broadband high-resolution elliptical crystal x-ray spectrometer for high energy density physics experiments Rev. Sci. Instrum. 77, 063115 (2006); 10.1063/1.2214688High-luminosity, high-resolution, x-ray spectroscopy of laser-produced plasma by vertical-geometry Johann spectrometer Rev.A simple, high-resolution x-ray imaging crystal spectrograph is described for on-line measurements and analysis of x-ray emission from laser-produced plasmas in the wavelength range of ϳ5-12 Å. The spectrograph uses a planar TAP crystal for dispersion and a phosphor-coated optical fiber plate followed by an image intensifier and a charge-coupled device camera for detection. The spectrograph covers a wavelength range of ϳ1.4 Å in a single shot about a desired wavelength setting with a spectral resolution of ϳ0.012 Å. It also has a design flexibility to cover the full spectral range of 5-12 Å in a single shot with a spectral resolution of ϳ0.040 Å. The spectrograph is particularly suited for studies involving low vacuum environment, e.g., plasma interaction with a background gas, laser interaction with a gas jet, etc., which preclude the use of other on-line detectors such as open-ended microchannel plates. An example of space resolved x-ray emission from laser-produced magnesium plasma expanding in a helium gas is also presented.

In this paper, an experimental study on generation of nanoparticle various sizes using Ti:sapphire laser pulses, is reported. Nanoparticle formation in plasma plumes of metals like silver and copper, expanding in vacuum, has been studied using stretched pulses of 300 ps duration [subnanoseconds (sub-ns)] from a Ti:sapphire laser. It has been compared with the nanoparticle formation (of the same materials) when compressed pulses of 45 fs duration were used under similar focusing conditions. Nanoparticle formation is observed at intensities as high as 2×1016 W/cm2. The structural analysis of the nanoparticle deposition on a silicon substrate showed that, using 45 fs pulses, smaller nanoparticles of average size ∼20 nm were generated, whereas on using the sub-ns pulses, larger particles were produced. Also, the visible light transmission and reflection from the nanoparticle film of Ag on glass substrate showed surface plasmon resonance (SPR). The SPR curves of the films of nanoparticles deposited by femtosecond pulses were always broader and reflection/transmission was always smaller when compared with the films formed using the sub-ns pulses, indicating smaller size particle formation by ultrashort pulses. Thus, it has been demonstrated that variation in the laser pulse duration of laser offers a simple tool for varying the size of the nanoparticles generated in plasma plumes.