The paper presents a theoretical model promoting estimation of characteristics of an acoustic flow-through filter used for particle fractioning; the model is constructed based on the analysis of joint action of the acoustic radiation force, Stokes force, and gravity on retaining the particles within the ultrasonic field. A case of a vertically installed ultrasonic chamber with ultrasonic field superimposed in parallel to the flow direction has been considered. Simulation with this model showed that it is possible to fractionize natural inorganic particles whose densities vary in the wide range (1500 to 9000 kg•m^–3) and particle sizes differ from the preset values by no more than ± 5 % (in case the solution is supplied from above). Notice that it is potentially possible to fractionize particles not only by size but also by density.

Institute for Analytical Instrumentation RAS, Saint-Petersburg

The paper describes a multilayer ultrasonic chamber with losses. Relations for calculating the chamber resonant frequencies by various methods have been derived. Therefore, it became possible to tune the chamber to resonance by varying the chamber layer geometry and acoustic characteristics. Relations for calculating radiation pressure in the chamber layers for the cases of zero and non-zero coefficients of the chamber wave "mobility" are presented. Numerical examples are analyzed.

Institute for Analytical Instrumentation RAS, Saint-Petersburg

The paper discusses a possibility of implementing a detection channel for charged particles (electrons or ions) based on a combination of a solid-state surface probe with an electrostatic energy analyzing system comprising a high-transmission high-resolution energy analyzer and an integral detector of charged particle beams. As the energy analyzer, a spectrometer based on an axially symmetric electrostatic toroidal mirror is used; it is characterized by high transmission and high energy resolution ensured by spatial superposition of two second-order focusing points and a high energy dispersion (1.5 times greater than that of hemispherical analyzers). The finest focusing is observed for charged particles moving at the angles of 28 to 55° from the axis of symmetry. The large solid angle of the incoming particle beam (two steradians) ensures the energy analyzer transmission of at least 30 % of 2π. The focusing is performed so that, at the beam angular divergence of 25°, the energy resolution at the base of the spectral lines can be better than δE/E = 0.1 %. Simple geometry of the field-forming electrodes makes the analyzer design quite compact and manufacturable.

Institute for Analytical Instrumentation RAS, Saint-Petersburg; Saint-Petersburg State University of Information Technologyes, Mechanics and Optics

The paper suggests a method for monochromatization and formation of ion beams from ion sources working at high gas pressure. The ion beams are monochromized due to particle energy spectrum transformation in high vacuum under the action of short electric pulses upon ions with subsequent focusing the ion beam by using a set of einzel electrostatic lenses. Analytic expressions that can be used to estimate time and spatial characteristics of the ion beam energy dissipation have been derived. The method suggested has a number of advantages as compared with another method described in literature.

Institute for Analytical Instrumentation RAS, Saint-Petersburg

The resolving power of ion mobility spectrometer with two shutting grids was measured at different initial pulse durations from 10 to 200 microseconds and different lengths of drift paths for ion reagent peak in air at room temperature and corona discharge ionization. Two stage separation induce increase in resolving power depending on initial pulse duration.

Institute for Analytical Instrumentation RAS, Saint-Petersburg

The paper considers measured ratios between the 131 m/e and 132 m/e ion peaks with intensity (area) ratio of 1 : 0.03 in the perfluorotributylamine mass spectrum with σ varying within the range of 0.005÷0.008 % (the small peak with respect to the large peak). Conditions under which the said measurement accuracy of those peaks ratio have been analysed. The measurements has been performed by quadrupole mass spectrometer МС7303 with the modified computer system. The direct goal of this investigation was to acquire technical information necessary to construct, for Research-Engineering Center NTT "Tsentrotekh-EHZ", a quadrupole mass spectrometer suitable for high-accuracy (0.002 %) measurement of silicon isotopic composition in SiF4 in the scope of the International Project aimed at creation of a New Mass Standard. The Project participants are Germany, Great Britain, France, Japan, USA, Australia, and Russia; on the part of Russia, the investigation is performed by NTT "Tsentrotekh-EHZ", branch of FGUP "PO EHZ" (leading organization), A.F. Ioffe PTI RAS, IHVV RAS and Radium Institute.

Institute for Analytical Instrumentation RAS, Saint-Petersburg

Methods for solving a mathematically incorrect inverse problem are considered. A new criterion for selecting the optimal solution is suggested; the method has been successfully tested in a numerical experiment. Based on the numerical experiment results, a method for successive non-destructive recovery of the surface optical profile has been suggested. The new criterion was also used to determine parameters of super-thin oxide films on silicon; the results obtained were physically reasonable.

Institute of Applied Physics NAS, Ukraine, Sumy *Institute for Analytical Instrumentation RAS, Saint-Petersburg

The paper describes some approaches to calculation of acoustic scatterers’ scattering amplitudes, which are used in various fields of wave and particle scattering theory. Both bulk and surface scatterers are considered. Specific examples of calculations obtained by various methods are presented.

Saint-Petersburg

The paper presents a solution algorithm to the axial-geometry two-dimensional Poisson’s equation by the boundary integral equation method for the case when the space charge cloud has smooth curved boundaries.

Institute for Analytical Instrumentation RAS, Saint-Petersburg

The paper presents a method of solving the axis problem related to the boundary integral equation method where the integral equation is transformed into a matrix equation by collocation and forth integration. In forming the matrix, especial attention has been given to the near-axis peculiarities of the integral equation kernel.

Institute for Analytical Instrumentation RAS, Saint-Petersburg

The paper considers operation modes of the micromechanical gyroscope (MMG) of the R-R type with superimposed and separated frequencies of primary and secondary oscillations. Methods for oscillation frequency superposition are analyzed. Theoretical investigations demonstrating advantages of the superimposed frequency operating mode are represented. Experimental results of MMG operation in the superimposed and separated frequency modes are given. The experimental results have confirmed the theoretical ideas.

Federal State Unitary Company Central Research Institute “Elektropribor”, Saint-Petersburg

The paper considers capabilities of the algebraic method for recovering "superimposed" mass spectrum peak amplitudes for known peak positions and half-widths. The method under analysis is based on the least-square solution of a set of linear equations where the number of unknowns is equal to the spectrum peak number, whereas the number of equations is equal to that of the spectrum counts. The paper presents the results of testing the method by using mass spectrum mathematical models. It has been shown that it is possible to estimate mass spectrum peak amplitudes of impurities whose masses are close to that of the basic product. To make the method sufficiently efficient, preliminary smoothing and filtration ensuring the signal/noise ratio over 500 should be performed.

Institute for Analytical Instrumentation RAS, Saint-Petersburg

The paper considers the problem of using adapted-basis spectral transformation in order to improve the spectrum resolution and filter mass spectrometric signals. As reference signals necessary to construct the basis, various functions fitting the mass spectrometric peaks are used. The simplest function used to fit mass spectrometric signals is Gaussian. In addition, mass spectrometric peaks can be fit with flat-top functions and functions describing signals distorted by the detection system with an electrometric amplifier having a large time constant. The paper demonstrates that the direct and inverse spectral transformations in the basis "adapted" to the peak shape make it possible to reliably recover parameters of individual peaks contained in a mixed signal in case different peaks can be fit by similar functions different only in the amplitude and position on the independent variable axis. The recovery quality does not depend on the peak width and number of data in the sample. When filtering noise by spectral transformation, one can obtain well smoothed peaks whose positions can be precisely estimated in case the signal/noise ratio is no less than three.

Saint Petersburg Electrotechnical University "LETI" (ETU) *Institute for Analytical Instrumentation RAS, Saint-Petersburg

The paper analyzes applicability of the direct and inverse transformations to the problem of removing noises from mass spectra. To find the low-frequency filter band that ensure optimal results while the resolution remains constant, a multilevel conversion of initial signal is used. As the optimality criterion, an entropy level was taken, which quickly decreases on the early stages of approximation and detailing and decreases much slower on the later stages. The paper presents the cases of filtering an actual mass spectrum by the method suggested.

Institute for Analytical Instrumentation RAS, Saint-Petersburg