Instruments and Experimental Techniques最新文献

The use of glass capillaries with an outer diameter at their sharp end of less than 0.3 μm as probes in a manipulator based on an atomic force microscope (AFM) operating in a dynamic full-contact mode is considered. Various aspects of setting up the feedback system in this mode of AFM operation were studied to correctly obtain an image of the topography of the sample under study. Examples are given of the use of capillaries as probes for moving nanowhiskers with a characteristic diameter of 100 nm and hexagonal boron nitride (hBN) flakes with characteristic sizes from units to hundreds of micrometers. The possibility of creating and moving liquid droplets with a volume of less than 100 attoliters has been demonstrated.

This article presents an automated setup for studying the nonlinear optical properties of crystals by single-beam Z-scan with the pulse duration of 5.3 ns. The scheme has been successfully applied to study the nonlinear refractive index of a polycrystalline ZnSe window. The experimental setup and data analysis are described in detail. The measured value of the nonlinear refractive index n₂ was (1.01 ± 0.09) × 10^–11 esu. The developed experimental setup can be used to study the nonlinear optical characteristics of new nonlinear crystals.

A methodology for the fully automated production of optical fibers with a subwavelength diameter has been developed. A detailed description of the implemented automated setup is provided, which enables the production of quartz fibers with a record-breaking small waist diameter of 400 nm, a taper length of up to 100 mm, and a transmission loss level of 0.4 dB at a wavelength of 1550 nm. The reproducibility of the fiber parameters with a desired geometry is ±30%. The proposed methodology for fully automated production allows the significant simplification and standardization of the production of fiber-optic elements of subwavelength diameter for creating efficient coupling elements for optical microresonators with a giant quality factor, as well as for manufacturing subwavelength fibers for optical filtering and absorption spectroscopy applications.

The possibility of cooling a ТеО₂ target during production of radionuclides based on ^123/124I has been investigated. Different cooling methods used in production of radiopharmaceuticals, as well as their advantages and drawbacks, are considered. A new method is proposed for cooling the front side of a solid target (a TeO₂ layer) by a fine-dispersed flow of sprayed water. Experiments have been conducted at the cyclotron of the Tomsk Polytechnic University on the cooling of a TeO₂ target irradiated by an accelerated deuteron beam. As a result, at a water flow rate of 15 mL/min and a spraying plume diameter of 38 mm, the beam thermal energy of 113 W has been dissipated at a target surface temperature of 120−130°C.

In this paper, the Penning ion sources (PIS) characteristics are studied applied to their use in an inertial electrostatic confinement (IEC) system based on a two-electrode spherical chamber. In the IEC chamber with deuterium filling, due to multiple oscillations of ion beams through a gas-plasma target inside the central electrode, a beam-target mechanism for generating neutron radiation is realized. Based on the method for the neutron yield calculating of IEC systems, the requirements for a PIS are formulated to ensure the neutron yield (2.5 MeV) in the range of 10⁶–10⁷ neutr./s. A computational and experimental study of the discharge combustion regimes in the PIS has been carried out depending on the configuration of the external magnetic field and comparison of the currents in the PIS and the currents through the central electrode of the IEC chamber in the pressure range from 0.1 to 10 mTorr. The optimal number of PIS in the considered spherical chamber of the IEC justified.

The research investigates the distribution of intensity and energy of X-ray radiation in the detector plane for three pulsed X-ray sources. The sources generate nanosecond duration radiation pulses with different maximum voltages: 90, 320, and 615 kV. The X-ray tubes of these sources are designed in a coaxial form, with a tantalum disc as the autoemission cathode, which has an internal hole whose diameter depends on the maximum voltage of the source. The anode is a sharpened tungsten rod with a diameter of 4 mm. Due to the electrode design, which allows for a relatively small focal spot at high voltages, the distribution of radiation intensity across the detector area differs from the classical Gaussian distribution. This difference is observed for sources with maximum voltages above 300 kV. The ability to obtain high-energy radiation allows for the application of these sources in obtaining dual-energy X-ray images. The dependence of the distribution of radiation with different effective energies across the detector area is investigated for efficient use of dual-energy processing.

The article describes a prototype device for monitoring the level of phase separation, which can be used for operational control of the delayed coking process in the petrochemical industry. A scheme and design of an experimental device developed by the authors, consisting of an organic plastic scintillator and an array of silicon photomultipliers, is presented. A computer simulation of the response of a scintillation detector under conditions of the actual geometry of the coke drum is presented. Experimental results demonstrating the performance of the device are presented.

The paper presents a description of a device for studying the emission spectra of phosphors for laser lighting systems when they are affected by laser radiation with λ = 405–450 nm with different values of power and current. The scheme of the device driver and its component base is described in detail. When using a laser device, the authors of the work obtained the values of the luminous flux depending on various values of current and electric power. The use of a thermal imager made it possible to register the thermal fields formed during this kind of impact. Based on the results of the work, it was concluded that the design of a laser device with adjustable current strength and electrical power obtained in the course of the work makes it possible to carry out various applied scientific research related to the study of the effect of laser radiation on matter.

A successful LINAC operation at Synchrotron Radiation Facility−Siberian Circular Photon Source (SRF SKIF) is directly related to the improvement of diagnostic methods for measuring the transverse profile and longitudinal distribution of the beam charge, which, in turn, requires the use of new materials or methods for their production. The thermal outgassing has been measured from aerogel and electrophoretically deposited P43 phosphor used in the LINAC diagnostic system of SRF SKIF.

The results of a study of three methods for determining the phase of signals from a heterodyne microwave interferometer are presented: phase calculation by processing digitized signals using software methods; direct phase measurement with an AD8302 detector; and phase measurements by quadrature detection. The results of phase measurements obtained by these methods are compared. The values of errors of each method are estimated and ways to minimize them are considered.