Instruments and Experimental Techniques最新文献

The main techniques used for gas extraction from solid geological samples for geochronological studies are their thermal destruction either in an isothermal mode, for example in a double vacuum furnace, or under the action of laser radiation. Approaches based on the use of laser technologies are more express and have a low-background. The article describes an original high-vacuum experimental setup based on an ytterbium fiber optic laser for gas extraction from milligram samples of rocks and minerals in a scanning mode. In the proposed configuration, a static vacuum of 10^–8 Torr can be achieved in the high vacuum laser cell. Heating of individual mineral grains to a temperature of over 1800°C is ensured. Using the example of the international standard for (U,Th)–He dating—Durango apatite—it is demonstrated that the laser installation ensures complete extraction of radiogenic helium from the mineral and can be used for isotope-geochronological studies.

The study investigates a non-intrusive static surface pressure measurement technique for a Blended Wing Body (BWB) model in low-speed wind tunnel testing using internal pressure channels. This approach eliminates external pressure taps, reducing aerodynamic disturbances and preserving model integrity. Pressure data were obtained using a multi-tube manometer, capturing surface pressure variations across spanwise and chordwise locations. The experimental results were compared with computational fluid dynamics (CFD) simulations, showing good agreement in regions of smooth flow, while minor discrepancies near flow separation zones were attributed to surface imperfections and unsteady effects. The internal pressure channels effectively transmitted pressure data with minimal losses, ensuring reliable measurements. Factors such as tube length, channel diameter, and response time were analyzed for their impact on accuracy, confirming the method’s feasibility for low-speed aerodynamic studies. The findings demonstrate that this technique provides a practical and effective alternative for surface pressure measurement without protrusions, making it suitable for applications where aerodynamic fidelity is critical. Key considerations for optimizing internal channel design and post-processing are discussed to enhance measurement accuracy. This study highlights the potential of internal pressure channels for improving aerodynamic testing methods in low-speed wind tunnel experiments.

The possibility of using a composite gas-discharge device based on a combination of capillary discharge and plasma cathode, eptron, in a pulse generator with an amplitude of up to 46 kV at a pulse-repetition rate of up to 300 kHz is shown. Two eptrons are used in the circuit: as a part of the voltage doubler and as an output nanosecond switch. A doubler recharging efficiency of 85% has been achieved.

New electronics was developed and mounted in 2022 to digitize signals from the tracking system of the Spherical Neutral Detector at the VEPP-2000 collider of the Budker Institute of Nuclear Physics. It is based on flash analog-to-digital converters and field programmable gate arrays and is used for digitization at a signal sampling rate of about 200 MHz with a resolution of 12 bits. Data are transmitted from each board to the data acquisition system via Ethernet with the bandwidth of 1 Gbit/s. Thanks to this, the new electronics is significantly better than the previous version in terms of the maximum event recording rate, and events can be recorded at a rate as high as 1.5 kHz. A special algorithm for extracting the amplitudes and response times from oscillograms has been developed. Data acquisition has been carried out with the new electronics since 2023. The resolution measured for the parameters of reconstructed tracks meets the requirements of 0.82° for the polar angle and 0.38° for the azimuthal angle.

The characteristics of a liquid-hydrogen target with a CH-208L cryocooler used to cool the target and produce liquid hydrogen are considered. The main components of the developed setup are a cryostat, a condenser, containers for liquefied hydrogen, a vacuum pumping system, and thermometry devices. The rates of hydrogen liquefaction in the cryocooler mode without a first-stage heat exchanger have been measured. The obtained values range from 50 to 100 mL/h, depending on the measurement conditions at containers with volumes of 150 and 500 mL. The filling capacity of the 150 mL container has been visually checked, and the 500-mL container has been checked by the curves of liquid hydrogen evaporation into the receiver. When the required liquid-hydrogen levels are reached, the filling of containers is stopped by activating the hydrogen pressure stabilization mode. The corresponding stabilization system has been developed using the functionality of the available temperature controller.

A wide-aperture objective lens (OL) is developed for experiments with ultracold ytterbium atoms and its characteristics are described. The OL consists of standard models of an aspherical lens and an achromatic doublet, has a numerical aperture of 0.4 and a working distance of 30–35 mm, and is adjusted for a 5‑mm-thick vacuum window. The formation of optical tweezers at a wavelength of 759 nm with a waist radius of 0.92 μm and an image of the optical-tweezers plane at a wavelength of 556 nm with a resolution of several microns has been experimentally demonstrated. The developed OL is simple to manufacture and suitable for use in a wide range of experiments (including those involving thulium atoms), in which the geometry of the vacuum chamber requires the use of an OL with a long working distance.

The article presents a multiparameter sensor designed to monitor the contamination of the surface of a spacecraft. The design and structural diagram of the device are described, including a quartz microbalance for measuring mass deposits and an impedance sensor for assessing the thickness of the deposited film and the dielectric properties of contaminants. Measurement methods are provided as well as the results of laboratory tests confirming the effectiveness of the proposed solution. The development allows for prompt monitoring of the degree of contamination and its nature, which is important for ensuring the reliability of the spacecraft under the influence of external factors.

Partial discharge (PD) detection is a common technique for assessing the state of insulation in high voltage equipment. To suppress noise in PD signals of electrical equipment, a denoising method combining with singular value decomposition (SVD) and generalized S-transform (GST) is proposed. The Hankel matrix based on the signal time series is constructed and the SVD is carried out to eliminate the periodic narrowband noise, whose singular values have the feature of appearing in pairs. According to the time-frequency diagram of GST, the PD signal with white noise was then intercepted. Finally, the effective sequence number K of the singular value was determined according to the standard deviation change of the normalized singular value subset to suppress the white noise. To evaluate the denoising effect, the algorithm was compared with two other algorithms. The simulation and measurement results show that this work could effectively suppress noise interference of PD with advantages of good noise suppression and high feature preservation.

A design of a nanosecond pulse generator is presented. The pulses are generated by the avalanche breakdown of the transistor, which also participates in the generation of the voltage required for the avalanche breakdown of the collector junction. As a result, the circuit is compact and operable from supply voltage 1.1 V. The circuit is very simple, does not require adjustment, and the parts used are available. The amplitude of the generated pulses is approximately equal to 40 V on a load of 50 Ω.

Traditionally, the calibration of the probe work function for Kelvin scanning microscopy is carried out using highly oriented pyrolytic graphite. In this paper, it is proposed to supplement it with calibration using indium- and fluorine-doped tin oxide (ITO and FTO). The study is performed using platinum- and gold-coated probes. Based on the calibration results, the positions of the Fermi levels of lead sulfide nanocrystals with ligand shells of 1,2-ethanedithiol and tetrabutylammonium iodide are determined. It is shown that the selected oxides are characterized by a stable working function, an additional calibration using these oxides helps to more reliably determine the absolute position of the probe work function, and gold probes provide a more stable result. The selected oxides can be used as an addition to the calibration using pyrolytic graphite, as well as independently.