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[en] Electron density was measured by Stark broadening in an ablative pulsed plasma thruster. The asymmetrical deconvolution is used to obtain Stark broadening. The result shows that the electron density in the discharge channel is 2.534x1022 m-3 when the discharge energy is 5 J and the measured electron temperature is 18 000 K, and it is in excellent agreement with other experimental and theoretical data. The electron density in the discharge channel increases very minimally with increasing discharge energy
[en] The structure and properties of quasicrystals are discussed. The short-and long-range atomic orders and the effect of these factors on the physical characteristics are considered. It is noted that investigations of the physical properties of quasicrystals at temperatures above room temperature should be performed. Promising applications are briefly outlined
[en] Thermally evaporated (Fe 3 nm/Dy 2 nm) multilayers have been magnetically and chemically investigated. Three-dimensional atom probe (3DAP) images related to multilayers revealed diffuse interfaces as well as the presence of Fe in Dy layers. Magnetic hysteresis loops measured on planar layers deposited on flat Si substrates show that the perpendicular magnetic anisotropy is much higher for the multilayers deposited at 600 K as compared to 320 K. 3DAP elemental maps show concurrently that the layered structure is degraded at 600 K. 3DAP analysis concerning an Fe/Dy multilayer deposited at 320 K on flat-topped Si posts is presented, and shows asymmetric interfaces
[en] In this article we present actual projects concerning high resolution measurements developed for future space missions based on ultracold atoms. This work involves the realization of a Bose Einstein Condensate in microgravitational environment and of an inertial atomic quantum sensor
[en] We report experimental results on the free cooling power available at the level of the second stage regenerator of a 4K pulse tube cooler. By using two localised heat exchangers we obtained additional cooling power, in the range 400 and 600 mW at 4.8 K or between 500 and 700 mW at 18 K. We have investigated in detail the thermal behavior of the system. In this manuscript we report on the evolution of the temperature of the heat exchangers and the pulse tube stages under different distributions of the total heat load.
[en] We investigate one-dimensional arrays of small capacitance Josephson junctions fabricated by conventional e-beam lithography techniques. The arrays are designed to operate in the vicinity of the Coulomb blockade regime. It has been suggested that charges propagate though these arrays in a form similar to solitary waves, following the sine-Gordon model. This system is dual to a long Josephson junction, in which magnetic flux solitons have been thoroughly investigated in the past. Localized charge excitations are of metrological interest because they might offer access to very accurate frequency-to-current conversion. Although previous experiments appear consistent with the existence of solitary charge transport, conclusive evidence is still missing. We present our recent fabrication and measurement results obtained at millikelvin temperatures.
[en] Measurements on thermal insulations in the temperature range −20 °C to 80 °C using the guarded hot plate method in accordance with both international and national standards have been shown consistently to have the claimed uncertainty of better than ±2% to ±3%. However, national and international intercomparisons have shown that significantly higher uncertainties (from the order of ±10% to ±18%) occur when measuring using EN 12667, at temperatures from 100 °C up to 600 °C and higher. Recently, the Technical Committee 89 of the European standardization body CEN has established a working group (WG 11) with the task of reviewing the current standard EN 12667 to ensure that it is suitable for making reliable measurements at high temperatures to the required level of uncertainty for providing declared performance values for products. Historically it appears that the guarded hot plate exists in two forms of a basic design that differ essentially only in the use of different materials for operation at low and high temperatures. Both are based on the principles and models for room temperature ambient conditions with assumptions that these apply to an operation at high temperature. The current analysis has identified a number of potential sources of error or uncertainty that can arise due to the effects of differences in materials used together with those due to changes caused by the elevated temperature operating conditions. As a result, it is possible to recommended means to minimize these effects in order to prepare a separate EN standard to reduce the uncertainty level to ±5% or better at elevated temperatures. These recommendations combined with a suggested protocol for undertaking measurements and proposals for further research are presented in the second part of this paper
[en] In this paper, an online self-compensation control scheme for micromachined gyroscope has been presented to eliminate the scale factor drift due to temperature influence. Firstly, the error sources of scale factor have been analyzed. According the analysis results, a novel control scheme which contains three loops has been proposed: a phase-locked loop of driving mode is to drive the proof mass oscillation in its' resonant frequency, an AGC loop of driving mode is to keep a constant value of the drive amplitude, an additional scale factor error online detection and cancellation loop is to keep the scale factor stable. A digital hardware prototype has been implemented to perform the precision loop control and self-compensation loop. Scale factor of the gyroscope has been measured in a temperature-controlled turntable. Experiment results show that the scale factor drift is -3.5% to 5.2% over the temperature range of -45 deg. C to +80 deg. C without the self-compensation loop, while the scale factor drift decrease to -0.009% to 0.15% after the self-compensation loop is applied.
[en] The high temperature leak before break (LBB) approach is supposed to be applied to the design of KALIMER-600. While the assessment of a crack instability is a essential element for an LBB application, solid methods for evaluation of a crack instability at high temperature condition are yet to be established even though it is well provided for in a PWR application. In this study, US BS7910, UK R5/R6, and French RCC-MR A16 were examined and a tentative procedure was presented for an LBB application to sodium cooled fast reactor KALIMER- 600
[en] Magnetic nanoparticles dispersed as a ferrofluid with volumetric concentrations in the range 0.4 to 10% and sizes ranging from 59-77 A have been studied via magnetic measurements at room and low temperatures. Remanence measurements have been used to determine switching and coupling effects. Particle size and concentration effects have been investigated and we find that the samples with higher concentrations have larger coercivities than expected due to coupling effects. Interactions have been found to be demagnetising overall as expected for dipolar interacting systems. Surface effects become evident below 10 K when thermal effects are weak