Instruments and Experimental Techniques最新文献

An acousto-optical cell has been developed to control the angle of rotation of the plane of polarization of optical radiation, changing the direction of the angle of rotation to the opposite depending on the range of acoustic frequencies. The cell prepared from paratellurite crystal made it possible to change the angle of rotation of the polarization plane by approximately 20° in one direction and by approximately 25° in the other when the sound frequency in the first case changed from 20 to 32 MHz and in the second case from 38 to 50 MHz. Time of switching between one polarization position to any another is approximately 1 μs.

The article proposes a method for measuring the absolute energy sensitivity of digital sensors depending on the wavelength of the recorded radiation. The principle of the method allows ignoring the internal software mechanism for processing information in the digital sensor. The results of testing the method for the case of a CCD sensor are presented based on processing the recorded images of radiation sources in the spectral range of 0.4–1.1 μm. The testing was carried out for two types of radiation sources, laser and incandescent lamp, with a discussion of their advantages and disadvantages. The proposed method will allow determining the amount of energy of radiation recorded in experiments in the corresponding local spectral intervals in which calibration was carried out. A demonstration calculation of the energy of radiation scattered by laser plasma is given.

This article introduces the investigation of colorimeters among the alternatives that can replace spectrophotometers in teaching educational spectrophotometry. The practicum was conducted by the Department of Chemistry at the College of Science and included deep practice aiming at the improvement of the understanding of spectrophotometry. The practice involved the application of Beer–Lambert’s law in color solutions, where the detectors were the smartphone cameras instead of the conventional spectrophotometers. Four color solutions, specifically Copper (II) Sulfate Pentahydrate (blue), Chromium Chloride Hexahydrate (green), Potassium Permanganate (pink), and Potassium Dichromate (yellow), were studied for the wavelength of maximum light absorbance. This will describe the color of these solutions using a spectrophotometric assay and the application of the color produced to be utilized in pharmacy, chemistry, and bacteriology, whereby determination involving trace metals, drug concentrations, or environmental monitoring will be done. The study aims at bringing out student independence and the most active participation possible during all phases of the practicum—from material preparation to the interpretation of the calibration curves. This approach helps to improve students’ practical skills and better understand the principles of spectrophotometry.

Accurate temperature measurement is essential for quality control and industrial process optimization. However, a major challenge in the temperature measurement arises when the emissivity of the object is unknown. Multi-wavelength temperature measurement has emerged as an effective solution to address this issue, as it allows for the simultaneous consideration of multiple wavelengths, compensating for unknown emissivity variations. In this work, a novel multi-wavelength radiation temperature inversion algorithm is proposed for the simultaneous determination of both the target temperature and spectral emissivity. This method is based on the assumption that the spectral emissivity of the object follows an exponential polynomial model. By utilizing different wavelength combinations, multiple overdetermined equations are constructed and the conjugate gradient least squares method is employed to solve these equations to obtain predicted temperatures. After acquiring multiple predicted temperatures, the adaptive kernel density estimation method is applied to model the probability density distribution of the predicted temperatures. Finally, the final temperature prediction is determined as the weighted average of all temperatures above a predefined threshold and emissivity is further obtained based on the final predicted temperature. The accuracy and reliability of this method are validated through simulation experiments under different emissivity models, as well as actual emissivity measurement data from four samples, and experimental results demonstrate that the method can offer a promising solution for overcoming the challenges associated with the traditional temperature measurement techniques.

The article describes the technique of reactor production and identification of the radioisotope ¹⁰³Pd, and the conditions for dissolving metallic palladium irradiated in the reactor and applying it to the ion-exchange column are selected. Experimental results of the efficiency of ^103mRh washing from the ion-exchange column with anionite Eichrom 1× 8 with a particle size of 200–400 Mesh in Cl^– form for several variants of its accumulation and elution are obtained. The value of the impurity activity of ¹⁰³Pd in the eluate with ^103mRh is measured. The stability of the ion-exchange column with repeated conditions of washing and accumulation of ^103mRh for approximately 1 month of its operation is demonstrated.

A two-channel scintillation spectrometer with a thickness of 0.5X₀ has been calibrated on the secondary electron beam at the Pakhra accelerator of the Lebedev Physical Institute, Russian Academy of Sciences. The amplitude and time recording systems of the spectrometer are based on FEU-49 and FEU-85 photomultiplier tubes, respectively. The relative energy resolution of the scintillation spectrometer is ~5% at electron energy E ∼ 30 MeV. The nonlinear dependence of the average channel of the time-resolved spectrum on the electron energy is observed at electron energies E < 40 MeV, and the average channel of the time-resolved spectrum is independent of the energy at E ≥ 40 MeV.

The paper discusses the diagnostic systems for a high-current electron beam of the LIA-20 linear induction accelerator which forms the basis of the X-ray complex. The complex is designed to form X-ray images of fast processes occurring in optically opaque dense media. The obtained X-ray images are used for calibration of computational codes and development of new physicomathematical models. Methods to determine position, current, energy, and cross-section of the beam, as well as the size of a focal spot on the conversion target, were developed to focus a high-intensity electron beam onto the conversion target in order to obtain high-quality X-ray images.

Plasma vortices significantly influence stability and confinement in tokamak devices. This study investigates the intricate interplay between vortices and blobs, coherent density structures, using a Mix-Probe system on the IR-T1 tokamak. By measuring ion saturation current fluctuations, vortex frequencies, radial and poloidal velocity fluctuations, and temperature fluctuations, we explore the temporal dynamics of these phenomena. Results indicate a strong negative correlation between vortex fluctuations and radial velocity, suggesting that increasing plasma rotation suppresses certain instabilities. Additionally, poloidal velocity fluctuations exhibit a positive correlation with vortex fluctuations, further emphasizing the impact of vortices on plasma dynamics. These findings provide valuable insights into the mechanisms underlying turbulent transport and plasma confinement in tokamak devices.

An electro-optical detector (EOD) of terahertz (THz) radiation has been developed. The basic operating principles of the device and the advantages of its application in THz spectroscopic systems are discussed.

The “Sun–Terahertz” space experiment is planned to be performed on board of the Russian segment of the International Space Station beginning with 2026. The objectives of the experiment are to obtain data on the terahertz radiation from the Sun, as well as to study solar active regions and solar flares. The “Sun–Terahertz” scientific equipment consists of eight detectors, whose target frequencies are in the range of 0.4–12.0 THz. A heat source is required for the primary calibration of the detectors of the scientific equipment. For this purpose, a blackbody simulator was developed, which allows directing flows from the radiating element at different temperatures to the telescopes of the scientific equipment. Based on the results of the experimental verification, conclusions were made about the accuracy of setting the temperatures by the measuring controller and about the temperature gradient from the center to the edge of the radiator mirror. This article may be useful for experimenters involved in thermophysical measurements, spectrometric scientific instruments based on opto-acoustic detector (Golay cell), and other sensitive elements.