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Introduction to the Kinetic Theory of Gases
Published in Caroline Desgranges, Jerome Delhommelle, A Mole of Chemistry, 2020
Caroline Desgranges, Jerome Delhommelle
Thanks to his experiment at Puy de Dome, Pascal proves the existence of a pressure, from the Latin pressio (action of weighting), exerted by the air on mercury. Nowadays, the notion of pressure is often used to measure height (or in other words, as a vertical coordinate in mountaineering or aeronautics). As a tribute to the work of Pascal and Torricelli, two units for pressure were created: Pa (for Pascal) and Torr (for Torricelli). One Torr corresponds to 1 mmHg (1 millimeter of mercury). Using Torricelli’s experiment, under ambient conditions, the height of mercury reaches 30 inches, or 760 mmHg, which is equivalent to a pressure of 1 atm (i.e. the atmospheric pressure). Let us add that another unit for pressure is also commonly used, the bar, with 1 bar = 100,000 Pa or 105 Pa.
Glossary of scientific and technical terms in bioengineering and biological engineering
Published in Megh R. Goyal, Scientific and Technical Terms in Bioengineering and Biological Engineering, 2018
Torr is an obsolete unit of pressure equal to that exerted by a column of mercury 1 mm high at 0°C and standard gravity (1 mm Hg); named after Evangelista Torricelli (1608–1647), the inventor of the mercury barometer. 1 Torr = 1/760 atm = 133.322 Pa.
Vacuum Gauges and Gas Analyzers
Published in Marsbed H. Hablanian, High-Vacuum Technology, 2017
The rotation of the ball induces a synchronous ac voltage in a pair of coils currounding the ball due to its magnetic moment. This signal is processed by high-speed digital counting circuitry to produce a pressure indication. The above indicates that the proportionality factor of this gauge depends on gas species and the length of the measurement depends on the pressure range. The behavior of the instrument regarding effects of temperature, loss of power, initial calibration, and long-term effects of surface changes of the ball, including contamination, have been studied extensively at the National Institute for Science and Technology (NIST) and a number of papers published in the vacuum journals. The accuracy of the gauge in the range 10−2 to 10−6 torr is claimed (by manufacturers) to be close to 1 % of reading with satisfactory long-term repeatability. The gauge can be mounted on a metal gasket flange and baked in an ultrahigh-vacuum system (after removing the driving and detector coils).
Electronic ionisation-induced annealing of pre-existing defects in Al2O3 and CaF2 single crystals
Published in Philosophical Magazine, 2022
M. Izerrouken, R. Hazem, S. Kuzeci, C. Tav, U. Yahsi, S. Limam
DBS technique is well sensitive to vacancies such as hole defects in materials. It is nondestructive and intensively used to study defects in nuclear materials [20–22]. In the present work, the measurement and depth-selective analysis of defects in near-surface regions were carried out using DBS on Variable Energy Positron Beam at Marmara Positron Laboratory (MARPOS) at Marmara University [23]. The measurements were carried out at about 10−8 torr high vacuum pressure and room temperature. The defect depth profiling is obtained by adjusting the positron energy from 0.05–29 keV. A high purity germanium (HPGe) detector of resolution 1.2 keV for 511 keV gamma rays was used for gamma-ray spectra acquisition. The mean position implantation depth given in nanometres is related to the positron implantation energy E by [24]: where ρ is the density (g/cm3), and E is the positron energy (keV). The densities of CaF2 and Al2O3 were taken as 3.18 and 3.95 g/cm3, respectively. Thus, the probed layer at positron energy of 29 keV is about 2.7 and 2.2 µm for CaF2 and Al2O3, respectively. According to SRIM calculation (see Figure 1), the energy loss in such layer is mainly through inelastic collision (electronic ionisation and excitation process).
Implanting bismuth in color-tunable emitting microspheres of (Y, Tb, Eu)BO3 to generate excitation-dependent and greatly enhanced luminescence for anti-counterfeiting applications
Published in Journal of Asian Ceramic Societies, 2020
Qi Zhu, Zhenshu Fan, Siyuan Li, Ji-Guang Li
Phase identification was performed by X-ray diffractometry (XRD, Model Smart Lab, Rigaku, Tokyo, Japan) operating at 40 kV/40 mA using nickel filtered Cu Kα radiation and a scanning speed of 6.0° 2θ/min. Morphologies of the products were observed via field emission scanning electron microscopy (FE-SEM, Model JSM-7001 F, JEOL, Tokyo) and transmission electron microscopy (TEM, Model JEM-2000FX, JEOL, Tokyo). Elemental mapping was performed using scanning transmission electron microscopy (STEM, Model JEM-2000FX, JEOL, Tokyo). X-ray photoelectron spectroscopy (XPS) data were measured using an X-ray photoelectron spectrometer (Model Axis Supra, Kratos Analytical Ltd., Manchester, UK) with monochromatized Al Kα X-ray radiation. The measurements were performed using an ultrahigh vacuum chamber with a base pressure below 3 × 10−9 Torr at room temperature. The binding energies were calibrated by using C 1 s (284.8 eV) of carbon impurities as reference. Photoluminescence and fluorescence decay of the phosphors were analyzed with an FP-8600 fluorospectrophotometer (Jasco, Tokyo). Fluorescence decay kinetics of Bi3+ emission was measured at room temperature on a HORIBA scientific modular fluorescence lifetime system (Model DeltaFlex, HORIBA Jobin Yvon IBH Ltd., Scotland).
Supersonic Gas Injector for Plasma Fueling in the National Spherical Torus Experiment
Published in Fusion Science and Technology, 2019
V. A. Soukhanovskii, W. R. Blanchard, J. K. Dong, R. Kaita, H. W. Kugel, J. E. Menard, T. J. Provost, R. Raman, A. L. Roquemore, P. Sichta
Flow rates also have been calibrated on a laboratory stand and in situ on NSTX using neutral pressure gauges (Fig. 17). The flow rate is measured as the amount of gas injected per unit time. The gas flow rate is commonly expressed in Torr liters/second. The amount of injected gas can be measured as , where is a neutral pressure difference due to the gas injection either in the SGI plenum of volume or the NSTX vacuum vessel volume . Both methods have inherent shortcomings. The SGI plenum pressure measured by the Sensotec sensor lacks high accuracy, while the plenum volume is known accurately m (125 to 250 cm3). The NSTX neutral pressures are measured accurately, however, the volume of NSTX vacuum vessel L may lack the required accuracy. In addition, the latter method can produce scatter in the measured flow rate due to ionization gauge calibration and different plenum pressure differentials for gas pulse lengths 5 to 300 ms used in the calibrations. It was found that during the SGI injection with the older plenum m (125 cm3) longer pulses lowered the plenum pressure and reduced the effective flow rates up to 10%.