Historical education in the system of engineers' and technical specialists' training

© the author(s). The importance and significance of the issue is determined by a new Federal State Educational Standard of higher education in Russia and changes in the system of engineers' and technical specialists' training. The report is aimed at the generalization of the experience and best practice of the new approaches to historical education implementation, mainly in higher educational establishments. The keynote methods in the research are historical and pedagogical methods. The report is focused on the application of the competence-based approach to teaching "History" in technical colleges through the organization of students' autonomy while studying the subject and implementation of interactive forms of education and on-line education. It reveals that a combination of the above mentioned approaches and forms of education in teaching "History" leads to the improvement of quality, progress in studies, professional competences advancement and the subject academic performance. The results of the research can be useful in teaching "History" in technical colleges and universities

Hybrid MHD/PIC simulation of a metallic gas-puff z pinch implosion

We present the hybrid MHD/PIC simulations of the time evolution of a bismuth metallic gas-puff z pinch in external axial magnetic field (AMF). Recent experiments with IMRI-5 generator (450 kA, 450 ns) [1] show the certain effect of an axial magnetic field on radiation energy produced during z pinch implosion. In order to perform the numerical simulation of gas puff z pinch a hybrid model was developed. The hybrid model treats the electrons as a massless fluid and ions as macroparticles. The macroparticle dynamic is calculated with the use of PIC method. Ion-ion Coulomb collision is considered with the use of MC method. The radiation transfer of bismuth plasma was accounted in the framework of P1 method. The interelectrode gap pumping by plasma of 8 μs 80 kA bismuth arc with the following plasma implosion by 450 kA / 450 ns current pulse in different external AMF was modelled. The obtained results are in a reasonable agreement with the experimental results. © Published under licence by IOP Publishing Ltd.The work was supported by Russian Science Foundation (project No. 16-19-10142)

Computer simulation of high current vacuum arc with developed anode spot

A self-consistent simulation of anode heating by 4.5 kA vacuum arc during the half-wave of 50 Hz current with 1 m/s contact opening was carried out. The calculations were done in the framework of hybrid high current vacuum arc model, which treats ions and atoms as macroparticles with the help of particle-in-cell methods, but electron subsystem is treated as massless fluid with quasineutrality assumed. The occurrence of an anode plasma plume (similar to that found in experiments) was obtained as a result of modeling. It is shown that the energy flux of line radiation from the interelectrode plasma to the anode is a critical reason of the appearance and maintenance of the anode plume. © 2019 IOP Publishing Ltd. All rights reserved.Russian Foundation for Basic Research, RFBRRussian Academy of Sciences, RAS: 1118-2-2-16This work was supported in part by RFBR (grants nos: 17-02-00346, 18-08-00547, 19-08-00783, 19-58-53006), by RAS Program (project no. 11) and UB RAS Program (project no. 18-2-2-16)

On Hybrid Type of Cathode Attachment in High Current Vacuum Arcs

This paper discusses the issues of a possible change of the type of cathode attachment of high-current vacuum arcs (HCVA) with an average cathode current density of more than 105 A/cm2. This type of HCVA is used as pumping plasma gun in experiments with plasma puff z-pinches. These experiments showed that the measured linear mass of the HCVA plasma jet is much higher (by a factor of 10 or more) than the expected mass, which can be obtained from the assumption that cathode attachment occurs only through a multitude of cathode spots emitting supersonic plasma jets. It is shown that in HCVA of the type under consideration, at some time instant there are two types of cathode attachments - cathode spots and thermionic erosion attachment (TEA). It can be said that HCVA of this type have a hybrid cathodic attachment. Unlike cathode spots, TEA produces a subsonic plasma flow, which contributes to an increase in the linear mass of the HCVA plasma jet. © 2021 Institute of Physics Publishing. All rights reserved

Modeling of plasma jet of vacuum arc with copper-chromium cathode under action of strong axial magnetic field

This paper deals with the computer simulation of a vacuum arc with composite cathode under action of external axial magnetic using hybrid model. The described hybrid model treats the electrons as a massless fluid and ions as macroparticles. It is shown that the average charge state of ions in a jet of a vacuum arc increases with increasing magnetic field. The calculation results are consistent with experimental data. © 2019 IOP Publishing Ltd. All rights reserved.Russian Science Foundation, RSF: 18-19-00069This work was supported by Russian Science Foundation (project No. 18-19-00069)

On possible reasons of positive near-anode voltage drop in high-current vacuum arc

In this paper we consider some reasons for the occurrence of a positive near-anode potential drop during current constriction in high-current vacuum arc. It is shown that if the radius of constriction is much larger than the electron mean free path, then a positive voltage drop in the near-anode plasma sheath does not occur, but an additional drop may occur in the near-anode plasma layer due to the anomalous resistance. If the current constriction radius is much less than the electron mean free path, then a positive voltage drop in the sheath arises under the usual condition, and the kinetic instabilities in the near-anode plasma do not develop. © 2019 IOP Publishing Ltd. All rights reserved.Russian Foundation for Basic Research, RFBR: 17-02-00346, 18-08-00547Russian Academy of Sciences, RASNational Natural Science Foundation of China, NSFC: 5191153011318-2-2-16This work was supported in part by RFBR(grant Nos. 17-02-00346, 18-08-00547, 19-08-00783, 19-58-53006), by RAS Program (project No. 11) and UB RAS Program (project No. 18-2-2-16), as well as by National Natural Science Foundation of China (project No. 51911530113)

Formation of double shell during implosion of plasma metal puff Z-pinches

This work presents the results of experimental and theoretical research of impact of tailored density profile and application of external axial magnetic field on initial spatial distribution of the plasma density in the plasma metal puff Z-pinch and on its implosion dynamics. It has been discovered that upon implosion of the plasma metal puff Z-pinch some stripes interpreted as the system of two coaxial shells appear on the optical images. With the help of numerical simulation, the formation of the plasma liner consisting of a mixture of carbon and bismuth ions and formed by the expansion of the plasma jet of the arc burning on the bismuth electrode has been considered in this work. It has been shown that the lightweight carbon ions facilitate formation of the density distribution smoothly decreasing with the increase in radius, that, in turn, leads to suppression of the Rayleigh-Taylor instability in the current sheath upon further implosion. It has also been demonstrated that availability of the two types of ions in plasma considerably different in mass leads to formation (in the compression phase) of a double shell with externally located heavy ions. It has also been revealed that the application of the external axial magnetic field leads to reduction in the plasma metal puff Z-pinch initial diameter. © 2020 Author(s).This work was funded by Russian Science Foundation. Project No. 19–19-00127

A transverse current rectification in graphene superlattice

A model for energy spectrum of superlattice on the base of graphene placed on the striped dielectric substrate is proposed. A direct current component which appears in that structure perpendicularly to pulling electric field under the influence of elliptically polarized electromagnetic wave was derived. A transverse current density dependence on pulling field magnitude and on magnitude of component of elliptically polarized wave directed along the axis of a superlattice is analyzed.Comment: 12 pages, 6 figure

Reorganization of a 2D disordered granular medium due to a small local cyclic perturbation

We measure experimentally the rearrangements due to a small localized cyclic displacement applied to a packing of rigid grains under gravity in a 2D geometry. We analyze the evolution of the response to this perturbation by considering the individual particle displacement and the coarse grained displacement field, as well as the mean packing fraction and coordination number. We find that the displacement response is rather long ranged, and evolves considerably with the number of cycles. We show that a small difference in the preparation method (induced by tapping the container) leads to a significant modification in the response though the packing fraction changes are minute. Not only the initial response but also its further evolution change with preparation, demonstrating that the system still retains a memory of the initial preparation after many cycles. Nevertheless, after a sufficient number of cycles, the displacement response for both preparation methods converges to a nearly radial field with a 1/r decay from the perturbation source. The observed differences between the preparation methods seem to be related to the changes in the coordination number (which is more sensitive to the evolution of the packing than the packing fraction). Specifically, it may be understood as an effect of the breaking of local arches, which affects the lateral transmission of forces.Comment: 13 pages, revised and resubmitted to J. Stat. Mech.: Theory and Exp. (JSTAT

Study of the ion plasma flow generated by a high-current vacuum arc

The vacuum arc discharge is intensively explored for a long time. It acts as a source of multiply charged plasma. The results of the special type plasma gun (5-10 kA, 12 μs) ion flow study with high temporal resolution and the electrode erosion dependences on the amplitude of the current pulse are presented in the research. The ion flow intensity had good reproducibility from series to series, while the values of total mass erosion differ significantly for different series of experiments under the same conditions. The ion erosion was measured to be significantly higher than that for arc sources with currents up to 1 kA. © 2019 IOP Publishing Ltd. All rights reserved.Russian Foundation for Basic Research, RFBR: 17-02-00346, 18-08-00547Russian Academy of Sciences, RAS18-2-2-16This work was supported in part by RFBR (grant Nos. 17-02-00346, 18-08-00547, 19-08-00783, 19-58-53006), by RAS Program (project No. 11) and UB RAS Program (project No. 18-2-2-16)