The paper presents electron beam sintering of functionally gradient (FGM) Al2O3/ZrO2 materials. An electron beam generated by a pre-vacuum plasma electron source for sintering was used. FGM were ...manufactured with different number of layers of aluminum oxide and zirconium dioxide powders. The layers differed in the percentage of components by volume. It is shown that the sintering of the composite sample occurs during electron-beam heating. After sintering for 10 min at 1600°C, the sample density increases up to 4 g/cm3. The presented photos of cross-sections of the samples indicate low pore content after sintering.
Consideration has been given to the effects of a longitudinal magnetic field in the discharge-emission system of a forevacuum plasma electron source on the conditions of generating a focused electron ...beam with high specific power. It has been shown that the creation of a magnetic field with an induction of up to 0.4 mT ensures the possibility of expanding the emission channel, and, accordingly, increasing the current and current density of the electron beam while retaining the electric strength of the accelerating gap. As a result, the power density of the electron beam of the forevacuum plasma electron source has been raised to the value q = 1.5·10
6
W/cm
2
.
The paper presents the results of studies devoted to an effect of deviation and scanning parameters on the value of power density of a focused electron beam generated by a plasma electron source in ...the forevacuum pressure range. It is shown that the change in the beam power density does not exceed 20% with an angle of beam deviation within 20 degrees in the investigated pressure range of 6-8 pascals in air. The results of selective sintering of powder system of zirconia-alumina by an electron beam generated by a forevacuum plasma electron source are demonstrated.
The results of studies of the influence of the cathode-gap dimensions on the initiation of the hollow-cathode effect in a glow-discharge system with an extended rectangular hollow cathode are ...presented. It has been established that the threshold current for the transition of the discharge to the combustion mode with a hollow cathode is determined by the size of the cathode gap. With a decrease in the width of the slot, the threshold current increases disproportionately; with an increase in the longitudinal size of the slot, this current sharply decreases.
Anapole states associated with the resonant suppression of electric-dipole scattering exhibit minimized extinction and maximized storage of electromagnetic energy inside a particle. Using numerical ...simulations, optical extinction spectroscopy, and amplitude-phase near-field mapping of silicon dielectric disks, we demonstrate high-order anapole states in the near-infrared wavelength range (900–1700 nm). We develop the procedure for unambiguously identifying anapole states by monitoring the normal component of the electric near-field and experimentally detect the first two anapole states as verified by far-field extinction spectroscopy and confirmed with the numerical simulations. We demonstrate that higher-order anapole states possess stronger energy concentration and narrower resonances, a remarkable feature that is advantageous for their applications in metasurfaces and nanophotonics components, such as nonlinear higher-harmonic generators and nanoscale lasers.
We present the results of our investigation on the influence of the geometry of a discharge-emission system on the parameters of the electron beam generated by the forevacuum plasma electron source ...based on the hollow-cathode glow discharge. The extraction of electrons was implemented through a single emission channel. We have determined the optimal geometric dimensions of the hollow cathode, yielding a maximum efficiency of the electron extraction at the beam power density level of 6⋅105 W/cm2.
The article presents electron-beam sintering of composite cermets based on aluminum oxide and titanium. An electron beam generated by a forevacuum plasma electron source for sintering was used. The ...sintering samples were made from fine-grained powders and compressed by uniaxial pressing. It is shown that when heated to 1600 °C, a powder mixture with a ratio of aluminum oxide of 50% (wt.) and 50% titanium (wt.) large pores are formed in the sample. Measurements of the emission spectrum of the beam plasma formed above the surface of the irradiated sample showed the presence of aluminum. This may be due to the evaporation of these components during electron beam irradiation.
We present our studies of the parameters of helium beam plasma. The beam plasma was generated by a powerful focused electron beam propagating through helium atmosphere at a pressure of 25 Pa. The ...beam power varied in the range 80 to 1000 W. We have determined the electron beam parameters that enable one to generate a beam plasma with a density greater than 1016 m−3. Using the plasma ions, we have conducted treatment of polymer materials. It has been shown that the beam plasma treatment in the forevacuum range of pressure enhances the hydrophilic properties of fluoroplastic surfaces.
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