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Density measurements of CaO-MnO-SiO2 slags were carried out using the Archimedean method. The density decreased with increasing temperature, and the negative temperature coefficient (-dρ/dT) was in the range of 1.46-3.10 × 10 -1 kg/m 3 K. At a fixed CaO content (25 wt%) and at a fixed SiO2 content (30 wt%), the density of CaO-MnO-SiO2 slag increased with increasing MnO content. The molar volumes of CaO, MnO and SiO2 at 1 773 K were estimated 21.0, 17.2, and 28.0 × 10 -6 m 3 /mol, respectively. The molar excess volume was expressed by , where Ω = -8.97 × 10 -6 m 3 /mol at 1 773 K. The thermal expansion coefficient decreased with increasing XSiO 2 because of the enhanced silicate network structure.KEY WORDS: Archimedean method; CaO-MnO-SiO2 slag; density; molar volume; silicate network structure; thermal expansion coefficient.

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Abstract-The grazing incidence interaction of a 10-keV electron beam with a planar surface of plexiglass is studied experimentally. Moreover, the electron passage through flat channels form ed by such surfaces is inves tigated. The experim ents reveal the presence of a guiding effect of the electron passage as in the case of a glass surface. However, there are some features, such as the existence of an initial elevation angle for the case of negative inclination angles of the plate. The form ation of self-consistent charge on the surface of the plexi glass and its drain w hen the current is turned off occur m ore slowly than on the glass surface. This fact points to the difference in the surface conductivity of insulators. To simplify analysis o f this m echanism , studying the interaction o f electrons w ith glass surfaces at graz ing incidence was carried out [5]. Experiments with glass plates revealed some features o f the process as com pared to analogous experiments w ith ion beams: a dependence o f the reflection on the length o f the plate and the presence o f a beam trace halo on the screen.To find out how the dielectric m aterial affects the nature of the charge distribution and the rate o f its for m ation, we have continued studying planar surfaces m ade of plexiglass (polymethylmethacrylate). EX PER IM EN TThe experimental schem e is shown in Fig. 1. The m ain units o f the setup were m ade o f nonm agnetic materials to elim inate the possibility o f the effect of a magnetic field on the electron beam. The samples were fixed to a goniom eter w hich allowed them to be tilted at angles up to 10 degrees relative to the beam axis and to be displaced in the horizontal plane, m ak ing it possible to simultaneously work with several sam ples and adjust the straight beam. A glass screen covered by a scintillator with a layout of 1.5 cm x 1.5 cm was m ounted at a distance of 24.5 or 32 cm from the axis of the beam depending on the experimental scheme. The m otion of the beam trace on the screen was recorded by m eans o f a webcam located outside the vacuum chamber. The sample was rotated successively by means of the goniom eter and photos were taken at each fixed angle. Dielectric SurfaceAn electron beam w ith an energy o f /:' = 10 keV, a mask current of 100 nA, a beam diam eter cross section of about 2 m m, and a divergence o f <0.2° was incident onto a planar dielectric surface at a glancing angle. The electron trace is created on the screen after inter action and is recorded using the webcam. Figure 2 shows a series o f images demonstrating displacement of the beam trace on the screen w hen the plexiglass plate of 50 m m length was tilted at angles ranging from -1° to 2.8° relative to the beam axis. The front part of the plate was covered with a grounded alum inum foil. The bright line o f the photo shows the trace level of the straight beam. The distance to the screen is 24.5 cm.On the whole, the character o f spot m otion on the screen is similar to that w hen turning the flat surface of the glass. Howe...