Instruments and Experimental Techniques最新文献

The energy density distribution of a radially converging low-energy (up to 25 keV) high-current electron beam has been measured using a sectioned three-channel calorimeter. The beam formation was performed using a two-sectioned cathode assembly. Eighteen resistively decoupled arc plasma sources triggered by a breakdown over the dielectric surface were built in the 4-cm-radius ring cathode of each section. The distance between the centers of sections was 4 cm. Measurements were performed both in the vacuum-diode mode (a pressure of residual gases of 0.006 Pa) and in the gas-filled diode mode (argon at a pressure of 0.08 Pa). It has been shown that the energy density in the central part of the beam is higher by 25–30% on average than in its peripheral parts; this can be acceptable for solving many tasks of surface modification of metals and alloys. Lifetime tests of the cathode assembly have shown its operation stability for 50 000 pulses in minimum.

A power supply system for an unmanned aerial vehicle (UAV) based on a cable connection with a primary source of electrical energy located on the earth’s surface is described. The ground power source from a standard three-phase network generates a galvanically isolated, constant output voltage that varies in the range of 350–435 V with an average electric power of up to 10 kW. A circuit based on a step-down type pulse current stabilizer with a subsequent link of a current inverter, a matching transformer, and a rectifier was used. The voltage of the ground power source is fed through the cable-rope to the UAV. The UAV power supply lowers the output voltage to 48 ± 2 V, with an output current of up to 135 A. Experimental data on the operation of the system on a load equivalent and UAVs are presented.

Experimental results of determining the resolution of radiography using the bremsstrahlung from the improved compact SEA-7 betatron with electron energy of 7 MeV are presented. Measurements were made using AGFA NDT D4 PbVacuPac X-ray films and Duplex IQI image quality indicator (model EN 462-5). The obtained results demonstrate a different resolution (approximately 0.16 mm) of thin wire pairs of the indicator in different areas of the radiation cone, i.e., a different horizontal size of the effective radiation focus (approximately 0.2 mm), which must be taken into account when analyzing radiographic images of real objects. The vertical size of the radiation focus (approximately 1.4 mm), which is perpendicular to the plane of the electron orbit, was also estimated.

The experimental results of measurements of the thermal conductivity of standard multilayer insulation (MLI) in vacuum and under conditions simulating the Martian atmosphere are presented. These measurements have shown that the thermal conductivity becomes approximately one third higher when the insulation moves from vacuum into the Martian atmosphere. The obtained results make it possible to correctly determine the heating power of MLI-coated instruments on the Martian surface and, thus, to use the standard MLI during both the flight period and operations on Mars’s surface. The MLI-coated ISEM instrument, which was a part of the Pasteur payload of the cancelled ExoMars-2022 mission, was used as an object of the experiment.

This work has been carried out as a part of the study aimed at creating a therapeutic in vivo ¹⁰³Pd/^103mRh generator of Auger electrons. The ¹⁰³Pd radionuclide can be produced in a metal rhodium target as a result of the Rh(p, n)¹⁰³Pd or Rh(d, 2n)¹⁰³Pd reaction. To extract ¹⁰³Pd from the target, it is necessary that rhodium be transferred into solution, which is a rather intricate task. A laboratory setup and a technique for express dissolution of rhodium have been developed. This technique consists in alternating cycles of rhodium dissolution (~2.5 h) with an alternating current of 15 A and recovery with a direct current of 1 A (15 min). The technique for reducing rhodium metal from Rh solution in 6 M hydrochloric acid has been tested in order to include it in a closed ¹⁰³Pd production cycle. The efficiency of the created laboratory setup is demonstrated using an example of the dissolution of a powder rhodium target irradiated with protons.

The systematic error in measuring the duration of flashes by the correlation counter that was developed by the authors earlier on the basis of a digital oscilloscope and a computer has been reduced by 1–2 ns by mathematical processing of input pulses and by correction of their recording times. The variance in the measured duration and delay of flashes does not change when the correction is applied. The technique has been tested on model flashes, and the time of sonoluminescence flashes has been clarified. The counter can be used to measure other fast events, e.g., in nuclear physics.

Information about charged particles emitted by plasma of high-current discharges is of interest both from the point of view of understanding the fundamental processes occurring in pulsed plasma and for applied problems. Compact magnetic spectrometers based on permanent magnets make it possible to measure the flux of charged particles from a plasma under conditions of strong electromagnetic noise. Imaging plates (IP) are one of the most commonly used types of detectors for detecting charged particles in laser-plasma and electric-discharge experiments. This paper presents the results of calibration of the BAS-MS IP when detecting electrons and the BAS-TR IP when detecting helium and tungsten ions. Calibration dependences of the sensitivity of the BAS-MS IP for electrons in the energy range of 0.65–50 MeV and the sensitivity of the BAS-TR IP for tungsten ions in the energy range from 20 eV to 650 keV are obtained, taking into account the angles of incidence of particles on the detector.

Alpha particle detection performances of a Hamamatsu R1828-01 model and a RCA 6342A model photomultiplier tubes (PMT) were tested. For the sensitivity of the PMTs to alpha particles, an Eljen AJ-440 model ZnS(Ag) scintillator material in sheet form was used in front of their windows. To test their performances, the alpha peaks of an ²⁴¹Am source and the energy resolution values of the detectors that composed of these PMTs were compared. It has been showed that R1828-01 model PMT utilized for fast timing measurements in radiation detection could be used in alpha particle detection efficiently. This work revealed its another advantageous feature in addition to existing specifications.

This work implements three fast measurement techniques based on the measure–stress–measure (MSM) method. These techniques, namely, measuring–around–({{V}_{{{text{th}}}}}), one–point on–the–fly (OTF), and pulsed current-voltage (PIV), were used to characterize three different technologies of metal–oxide–semiconductor field-effect transistors (MOSFETs) with same gate dielectric silicon–dioxide (SiO₂) and various thicknesses ({{t}_{{{text{ox}}}}}) = 20 nm, 4 nm, 2.3 nm. Moreover, well–configured electrical stress biasing has been performed to discuss the dielectric degradation of these devices using those characterization techniques. The pros and cons of the used techniques are well discussed based on our results. Furthermore, experimental results showed that threshold voltage shift ((Delta {{V}_{{{text{th}}}}})) follows a power law time dependence with time exponent (n) being 0.16 for molecular hydrogen (H₂) diffusing species and 0.25 for hydrogen atoms (H) diffusing species. We have found that the thicker the SiO₂ dielectric the more the oxide traps (({{N}_{{{text{ot}}}}})) contribute to the resulting degradation. However, the dependency between SiO₂ dielectric thickness and oxide traps could not be necessarily linear.

A closed noncontact method of converging radial temperature waves generated by high-frequency induction modulated heating of a cylindrical sample, which is intended to study the thermophysical properties of metals and alloys at high temperatures, and an experimental setup for its implementation based on modern equipment are described. According to the experiment, the thermophysical parameters are determined with the following errors: 2% for the thermal diffusivity, 3% for the heat capacity, 5% for the thermal conductivity, 1.4% for the electrical resistivity, and 2% for the power. The following quantities were then calculated: the density, coefficient of volumetric thermal expansion, electron and lattice thermal conductivities, volumetric heat capacity, heat absorption coefficient, monochromatic and integral degrees of blackness, enthalpy, entropy, and Gibbs energy. When studying a substitution alloy and an interstitial alloy, the advantages of the closed method are shown on a specific example.