Analysis of an Inhomogeneous Semitransparent Plasma by the Lines in the Emission Spectrum

Using the methods of numerical simulation, we have investigated the dependence of the intensity and parameters of the spectral line profiles in the radiation of semitransparent plasma on its optical thickness, the degree of inhomogeneity, and the parameter distribution. As a model, we used the equilibrium plasma of argon with a given temperature profile on the observation line. The calculation has been performed for the spectral lines of the argon atom characterized by different broadening constants. On the basis of the results obtained it has been shown that it is possible to diagnose the plasma and determine the degree of its inhomogeneity and reabsorption by the parameters of the self-reversed profiles of the spectral lines. To diagnose the plasma in the absence of self-reversal, we propose to use the line intensities in the emission spectra of the plasma, including those obtained by probing it by its self-radiation. __________ Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 72, No. 3, pp. 404–411, May–June, 2005.     

Performance Validation for Microplate Fluorimeters

As the sophistication of instruments that make fluorimetric measurements on samples in microplates has increased, so has the need for methods to validate instrumental performance. This paper describes a solid-state validation microplate that tests multiple aspects of fluorescence performance, including signal linearity, gain, noise, sensitivity, wavelength accuracy, and polarization stability. Both the operating principles and the validation of the validation microplate are discussed.     

Development and application of the intense slow positron beam at IHEP

This paper describes the development and application of an intense slow positron beam at IHEP with regard to its two main components.The Variable-Energy Positron Lifetime Spectroscopy (VEPLS) based on the pulsing system consisting of a chopper,a prebuncher and a buncher has been constructed in order to meet the needs of materials science development.At present,the time resolution of the VEPLS can easily reach about 386 ps with a peak-to-background ratio of about 600:1.A plugged-in 22Na positron source section for adjusting the newly built experimental station and for increasing the beam operation efficiency has been constructed.A slow positron beam with an intensity of 2.5x105 e+/s and the beam profile whose diameter is 10 mm has been obtained;the moderation efficiency of the tungsten mesh moderator reaches 5.1x 10-4 as calculated with an original positron source activity of 52 mCi.     

Optically-Pumped Far-Infrared Laser Lines of Methanol Isotopomers: 12CH3OH, 12CH3OD, and 12CH2DOH

Twenty-seven new far-infrared laser lines from the isotopomers of methanol: ¹²CD₃OH, ¹²CH₃OD, and ¹²CH₂DOH, were obtained by optically-pumping the molecules with an efficient cw CO₂ laser. The CO₂ laser provided pumping from regular, sequence, and hot-band CO₂ laser transitions. The 2-m long far-infrared cavity was a metal-dielectric waveguide closed by two, flat end mirrors. Several short-wavelength (below 100 m) lines were observed. The frequencies of 28 laser lines observed in this cavity (including new lines and already known lines) were measured with a fractional uncertainty limited by the fractional resetability of the far-infrared laser cavity, of 2 parts in 10⁷.     

Extremal Processes with One Jump

Convergence of a sequence of deterministic functions in the Skorohod topology implies convergence of the jumps. For processes with independent additive increments the fixed discontinuities converge. In this paper it will be shown that this is not true for processes with independent max-increments. The limit in of a sequence of stochastically continuous extremal processes may have fixed discontinuities. Our construction makes use of stochastically continuous extremal processes whose sample functions have only one jump.     

Robust H{infty} control for Markovian jump nonlinear systems

This paper deals with the robust H control problem of uncertainnonlinear stochastic systems with Markovian jump parameters.We assume that the uncertainties are structured such that suitablebounding functions can be found. A robust controller is thendesigned that will guarantee disturbance attenuation and asymptoticstability for all admissible uncertainties and L₂-bounded disturbances.The solution to the problem is characterized in terms of a setof smooth-positive semidefinite functions satisfying certainHamilton-Jacobi-Isaac (HJI) inequalities with some appropriatescaling functions. Both the case of matched and unmatched uncertaintiesare considered.     

Specific Features of Light Scattering in [N(CH3)4]2CuCl4 Crystals with an Incommensurable Phase

We present the results of investigation of the optical birefringence and intensity of the main light beam that passed through an [N(CH₃)₄]₂CuCl₄ crystal under the conditions of viscous interaction of the incommensurable structure with defects. A nonmonotonic temperature dependence of the basic signal is revealed. The observed temperature dependence of the intensity (in the form of irregular steps) is related to different periods of the incommensurable structure. In transitions between adjacent metastable states the periodicity of the incommensurable structure changes. It is shown that in transition regions for the central beam one observes an anomalous decrease in the light intensity due to the appearance of a perturbation lattice with the wave vector q.     

Optically-Pumped Far-Infrared Laser Lines in Hydrazine, Methanol, Heavy Water, and Ammonia: New Laser Lines and Frequency Measurements

A far-infrared laser cavity designed to favor short-wavelength laser lines was used to generate optically-pumped far-infrared laser radiation. New far-infrared laser lines were discovered in hydrazine, heavy water, ammonia, and several short-wavelength lines previously discovered in methanol were observed. Wavelength, frequency, and relative intensity measurements were performed on laser lines in the wavelength range 42.4 to 253.7 m. Each far-infrared frequency measurement was obtained by mixing the far-infrared radiation with radiation from two reference CO₂ lasers and from a microwave synthesizer in a metal-insulator-metal diode. The pump laser was a high-Q Fabry Perot resonator oscillating on 275 grating-selected laser lines including regular, sequence, and hot band lines.     

1.5 μm Ti:LiNbO3电光波导强度调制器

用钛内扩散技术和常规光刻手段,研制出1.5μmLiN_bO₃电光波导强度调制器。它由单模波导非对称Mach-Zehnder干涉仪和三电极共平面波导组成。干涉仪的两个臂长相差波导波长的四分之一,使器件在最佳线性点工作,无需外加电偏压。集总调制和行波调制的理论带宽分别为1GHz和7.8GHz。对于集总器件,测量了调制特性,半波电压为9.5V,调制带宽为0.7GHz。     

Brillinger type mixing conditions for a simple branching diffusion process

A simple branching diffusion process is described. Formulae for intensity functions and factorial cumulant density functions at several times are given. Mixing conditions in terms of integrals of these cumulants are defined and proven for this stochastic evolutionary point process. The mixing conditions then allow a spatial central limit theorem and a strong law of large numbers to be easily obtained.