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A sheet plasma is generated by a mesh anode and a single hot-filament cathode with a DC power supply, and its characteristics are experimentally investigated. The sheet plasma is observed to locate around the anode. Both electron density and electron temperature derived from the average energy of the energetic electrons in nitrogen are estimated to be 10 cm−3 and 20~ 40 eV, respectively, using the optical emission spectroscopy (OES) method based on a kinetic model of low-pressure nitrogen discharge. The electron density, electron temperature and their spatial distributions are found to be affected by the supplying voltage on the anode (70 V to 300 V), filament temperature (600°C to 780°C) and gas pressure (2 Pa to 20 Pa). By adjusting these parameters the discharge status can be easily controlled.

A transmission grating spectrometer has been fabricated for the study of X-ray radiations from Z-pinch plasma. The spectrometer contains a 3 333 lp/mm gold transmission grating and an X-ray CCD to record time-integral spectral images. Two slits are employed in the spectrometer. One is used for 1D space resolving and the other, working together with the grating’s entrance slit, can collimate the incident X-rays and thus improve the spectral resolution of the spectrometer. The spectrometer has been used in Z-pinch experiments performed on Yang accelerator. When using Al wire arrays as Z-pinch loads, the Al K-shell lines and lines from Li-like ions were observed. In addition, by comparing the spectral image with the image obtained from an X-ray pinhole camera, the K-shell radiations emitted

The optical emission spectroscopy of a surface dielectric barrier discharge plasma aerodynamic actuator is investigated with different electrode configurations, applied voltages and driving frequencies. The rotational temperature of N2(C3∏u) molecule is calculated according to its rotational emission band near 380.5nm. The average electron energy of the discharge is evaluated by emission intensity ratio of first negative system to second positive system of N2. The rotational temperature is sensitive to the inner space of an electrode pair. The average electron energy shows insensitivity to the applied voltage, the driving frequency and the electrode configuration.

An atmospheric pressure plasma jet (APPJ) using radio-frequency (13.56 MHz) power has been developed to produce homogeneous glow discharge at low temperature. With optical emission spectroscopy, we observed the excited species (atomic helium, atomic oxygen and metastable oxygen) generated in this APPJ and their dependence on gas composition ratio and RF power. O and O2(b1?g+) are found in the effluent outside the jet by measuring the emission spectra of effluent perpendicular to the jet. An interesting phenomenon is found that there is an abnormal increase of O emission intensity (777.4 nm) between 10 mm and 40 mm away from the nozzle. This observation result is very helpful in practical operation.

Summary form only given, as follows. Diamond films and carbon nanotubes can both be synthesized by microwave-plasma enhanced chemical vapor deposition (MECVD) technology. When a mixture of methane, nitrogen and hydrogen is used to generate the discharge, either diamond or graphite phases, or both, can be formed on the substrate. Using optical emission spectra (OES), we have found a strong correlation between the type of active species (CN and CH) and the phase of growth on the substrate. In particular, in the case of carbon nanotube growth, intensity ratio of CN and C/sub 2/ radicals was found to be closely related with morphology, microstructure and graphitization degree of the samples prepared at different CH/sub 4//N/sub 2/ ratio. Carbon nanotubes show well aligned from SEM picture at about 20% CH/sub 4/ ratio, longer in length and denser in distribution indicate high growth rate. "Nanobell" structure from TEM results is polymerized when nitrogen dominates in the mixing gas and the length and thickness of the nanobells varied with the CH/sub 4/ ratio. Raman spectra show better graphitization of sample at low CH/sub 4/ ratio and more amorphous structures form when CH/sub 4/ ratio increase. Relative concentration of CN to C/sub 2/ radicals benefits to the alignment of nanotubes and is disadvantageous to the graphitization of samples. However, in the case of diamond growth, as indicated by optical emission spectra, CH radicals play key role in the diamond phase formation process. The effect of these radicals in plasma to the formation of diamond and graphite phase is briefly discussed.

In this paper, the principle of the collisional-radiative model for the estimation of plasma parameters from the ratios of K-shell spectral lines was introduced. The structure of a computer program, ZSPEC, developed for the analysis of K-shell line spectra emitted by Z-pinch plasma based on the collisioanl-radiative model was described in detail. The calculation for neon plasma were presented, including the number fractions of major ionization stages at different electron temperature and the contours of K-shell line ratios in the plane defined by electron density and electron temperature. ZSPEC had been used to analyze the measured results of neon gas-puff Z-pinch experiment performed on Yang accelerator. By comparing the K-shell line ratios of neon plasma obtained by an elliptical crystal spectrometer with the results calculated by ZSPEC, the time and space averaged electron temperature and electron density of the K-shell plasma for the shot with 540 kA peaking current were determined to be 240 eV and 1.0×1019 cm-3, respectively.

Based on Monte Carlo simulation of neutron penumbral imaging，the linear space invariance is researched. In the field of view，the points broadening linearly depends on the axial distance on the object plane，but the integrated intensity keeps linear space invariance. Using this result，the alignment precision is analyzed. The axial error of the targets center on the object plane should be controlled within 50μm. The point source should be less than 300μm away from the object plane. The aperture rotation should be within 0.1mrad.

This article carries out synthetic measurements and analysis of the characteristics of the asymmetric surface dielectric barrier discharge plasma aerodynamic actuation. The rotational and vibrational temperatures of an N 2 (C 3 II u ) molecule are measured in terms of the optical emission spectra from the N2 second positive system. A simplified collision-radiation model for N 2 (C) and N 2 + (B) is established on the basis of the ratio of emission intensity at 391.4 nm to that at 380.5 nm and the ratio of emission intensity at 371.1 nm to that at 380.5 nm for calculating temporal and spatial averaged electron temperatures and densities. Under one atmosphere pressure, the electron temperature and density are on the order of 1. 6 eV and 10 11 cm −3 respectively. The body force induced by the plasma aerodynamic actuation is on the order of tens of mN while the induced flow velocity is around 1. 3 m/s. Starting vortex is firstly induced by the actuation; then it develops into a near-wall jet, about 70 mm downstream of the actuator. Unsteady plasma aerodynamic actuation might stimulate more vortexes in the flow field. The induced flow direction by nanosecond discharge plasma aerodynamic actuation is not parallel, but vertical to the dielectric layer surface.