Персона: Губский, Константин Леонидович
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СИСТЕМА ЛАЗЕРНОЙ ОЧИСТКИ ПОВЕРХНОСТИ ЗЕРКАЛ ОПТИЧЕСКИХ ДИАГНОСТИК НА ИТЭР
The development of cleaning optics and deposition-mitigating techniques is a key factor in the construction and operation of optical diagnostics in ITER. It has been shown that high initial reflection characteristics of optical elements can be recovered by choosing regimes of fiber laser radiation effect on the deposited surface. Experiments on transport of fiber laser radiation to the metal mirror by using system of lens and cleaning showed the possibility of a hardware implementation of methods applicable in the geometry of port-plug ITER.
Impactor velocity measurement system for dynamic hardness testers and calibration machines on Leeb scales
© 2020 Elsevier LtdThe article aims to solve the problem of measuring the impactor velocity for dynamic hardness testers according to the Leeb, as one of the key parameters to ensure the accuracy and reliability of hardness measurements by this method. The gravitational method of impactor acceleration, used in calibration machines, and spring acceleration, typical for hardness testers, have been studied. Various technical solutions for velocity calibration are analyzed. Accurate, easy to implement, compact and inexpensive device based on fiber optic and allows monitoring the dynamics of the object without the use of additional reflective elements is developed. This system suitable for calibration or verification of dynamic hardness testers and calibration machines. The system is based on a laser interferometer in which the direct optical heterodyning of Doppler signals (Photonic Doppler Velocimetry) is applied. The maximum permissible error of the system is determined by the requirements for the metrological characteristics of the Leeb hardness calibration machine and is 0.0025 m/s at a speed of ~2 m/s. The possibility to measure the impact body velocity with an error of 0.2·10-3 m/s is confirmed.
Diagnostic system for shock processes investigation in matter under the influence of intense laser pulses
© 2019 Published under licence by IOP Publishing Ltd. The paper presents the diagnostic system for velocity measurements of reflecting objects in high energy physics experiments. The principle of continuous velocity measurements based on the Doppler frequency shift analysis of a probe monochromatic wave reflected by the moving surface of the sample. System is designed to measure velocity in the interval of 5-50 km/s. Powerful laser pulses expose the target and generate shock waves inside it. The back side of target is illuminated by probe laser beam at a wavelength of 660 nm. Scattered probe light collected by a lens and injected into the optical system. Two Mach-Zehnder interferometers with different reference delay etalons form a vernier measuring system. A passive channel records luminescence in the shock wave front. Spatial resolution of the optical layout is about 3 μm.
3D push–pull heterodyne interferometer for SPM metrology
© 2019 Optical Society of America.A three-coordinate heterodyne laser interferometer has been developed to measure the displacement of the probe microscope scanner with a subnanometer resolution that provides traceability of measurements to the standard of meter through the wavelength of a stabilized He–Ne laser. Main sources of errors are investigated, and their influence is minimized so that the resulting measurement uncertainty of the system does not exceed 0.2 nm, and the resolution is 0.01 nm. The investigation of metrological characteristics of the three-coordinate interferometer was carried out with a scanning probe microscopy (SPM) NanoScan-3D using TGZ-type calibration gratings. The values measured with SPM fell within the 95% confidence interval given by Physikalisch-Technische Bundesanstalt (PTB) (Germany). SPM equipped with a laser interferometer was used to measure the characteristics of dynamic etalons of geometric dimensions.
Inferring possible magnetic field strength of accreting inflows in EXor-type objects from scaled laboratory experiments
© K. Burdonov et al. 2021.Aims. EXor-type objects are protostars that display powerful UV-optical outbursts caused by intermittent and powerful events of magnetospheric accretion. These objects are not yet well investigated and are quite difficult to characterize. Several parameters, such as plasma stream velocities, characteristic densities, and temperatures, can be retrieved from present observations. As of yet, however, there is no information about the magnetic field values and the exact underlying accretion scenario is also under discussion. Methods. We use laboratory plasmas, created by a high power laser impacting a solid target or by a plasma gun injector, and make these plasmas propagate perpendicularly to a strong external magnetic field. The propagating plasmas are found to be well scaled to the presently inferred parameters of EXor-type accretion event, thus allowing us to study the behaviour of such episodic accretion processes in scaled conditions. Results. We propose a scenario of additional matter accretion in the equatorial plane, which claims to explain the increased accretion rates of the EXor objects, supported by the experimental demonstration of effective plasma propagation across the magnetic field. In particular, our laboratory investigation allows us to determine that the field strength in the accretion stream of EXor objects, in a position intermediate between the truncation radius and the stellar surface, should be of the order of 100 G. This, in turn, suggests a field strength of a few kilogausses on the stellar surface, which is similar to values inferred from observations of classical T Tauri stars.
Vernier laser diagnostic system for velocity measurements at Angara-5-1 facility
© Published under licence by IOP Publishing Ltd.The report presents a laser diagnostic system designed to analyze the behavior of a matter in extreme states and the propagation of shock waves. The research system consists of a pair of velocity interferometer systems for any reflector (VISAR), push pull and conventional VISARs, forming a vernier scheme. This configuration was designed for Angara-5-1 facility. Test experiments of metal plate acceleration using magnetic field were carried out. The velocities up to 6 km/s were obtained.
Accuracy of the interferometric method for Leeb hardness testers calibration
© 2021 Author(s).In this article, we propose a method for improving accuracy in calibrating Leeb hardness testers using fiber interferometric systems. The calibration system is implemented using the photonic Doppler velocimetry technique. This paper provides estimates of the measurement uncertainty arising in the calibration system and describes a method for improving accuracy, which takes into account the signal-to-noise ratio, sampling rate, and processing parameters.
Use of Direct Optical Heterodyning for Measuring Hardness by the Leeb Method
© 2019, Pleiades Publishing, Ltd.Abstract: In this paper, we describe a portable system for measuring the indenter velocity in hardness meters implemented according to the Leeb method. The developed system is a fiber interferometer, in which a radiation source is a semiconductor laser with a wavelength of 1550 nm. The presented experimental results confirm the ability of the system to measure indenter velocities with an uncertainty of 0.001 m/s, which satisfies the requirements of the standards for this method of measuring hardness.
Combination of the velocity interferometer system for any reflector and the photon Doppler velocimetry methods to study transparent and absorbing condensed matter
© Published under licence by IOP Publishing Ltd.The paper proposes a method for combining photon Doppler velocimetry and a system of speed interferometers for any reflective systems, which allows one to study the behavior of transparent media under the action of powerful shock waves without the use of additional reflective surfaces. The paper presents the results of an experiment on the propagation of a shock wave in water. In this experiment, water was an absorber; however, the proposed method would also work provided that the test material is transparent and provides reflection.