ION GENERATION BY TUNGSTEN FILAMENT FOR PYROELECTRIC PULSED ACCELERATOR

The article is devoted to investigation of ion generation by tungsten filament in vacuum. Electron and ion currents from tungsten filament at different residual air gas pressures are measured and compared. Dependencies of ion and electron currents from tungsten filament on its supply voltage are measured. Production of ions in the vicinity of the filament is discussed. Prospects of tungsten filament’s application in pyroelectric and piezoelectric pulsed accelerators are discussed.

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Radiation induced ion currents in vacuum due to residual air, He, and H, and their expected effect on insulating surfaces

Fusion Engineering and Design ◽

10.1016/j.fusengdes.2007.05.011 ◽

2007 ◽

Vol 82 (15-24) ◽

pp. 2578-2581 ◽

Cited By ~ 10

Author(s):

E.R. Hodgson ◽

A. Moroño ◽

S.M. Gonzalez de Vicente

Keyword(s):

Ion Currents ◽

Expected Effect ◽

Insulating Surfaces ◽

Radiation Induced ◽

Residual Air

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Maximum ion currents from flames and the maximum practical effects of applied electric fields

Proceedings of the Royal Society of London Series A - Mathematical and Physical Sciences ◽

10.1098/rspa.1964.0035 ◽

1964 ◽

Vol 277 (1371) ◽

pp. 468-497 ◽

Cited By ~ 72

Keyword(s):

Electric Field ◽

Space Charge ◽

Electric Fields ◽

Laminar Flames ◽

Limiting Current ◽

Ion Currents ◽

Forming Process ◽

Ion Generation ◽

Two Factors ◽

Current Densities

The maxima limiting all practical effects of the movement of flame ions in electric fields are shown to depend on the current densities available. The theory of the electric field and space charge distributions inside and outside the flame is developed, checked experimentally, and used to deduce such maxima. Two factors are identified as limiting current densities; the rate of ion generation per unit flame area and the space charge-induced breakdown at the electrodes. The latter is shown to be ultimately limiting and the theory is used to calculate numerical values for all practical maxima. The former is limiting only in some flat laminar flames parallel to electrodes, but it leads to a method of measuring rates of ion generation in flames. The method is developed experimentally on the basis of the theory and applied to a series of hydrocarbon/air and hydrogen/hydrocarbon/air flames. As an example of its use, the results are applied to calculations of activation energies and orders of the ion-forming process.

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The measurement of low gas pressures in terms of ion currents

Vacuum ◽

10.1016/s0042-207x(70)80290-1 ◽

1970 ◽

Vol 20 (2) ◽

pp. 56-64 ◽

Cited By ~ 5

Author(s):

K Close ◽

J Yarwood

Keyword(s):

Ion Currents ◽

Gas Pressures

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A New High Intensity Grid Cap for RCA-EMU-3 Electron Microscopes

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100101323 ◽

1968 ◽

Vol 26 ◽

pp. 316-317

Author(s):

George Christov ◽

Bolivar J. Lloyd

Keyword(s):

Electron Beam ◽

Electron Microscope ◽

High Voltage ◽

High Intensity ◽

Electron Gun ◽

Tungsten Filament ◽

Fluorescent Screen ◽

Electron Microscopes ◽

Pass Through ◽

Ground Potential

A new high intensity grid cap has been designed for the RCA-EMU-3 electron microscope. Various parameters of the new grid cap were investigated to determine its characteristics. The increase in illumination produced provides ease of focusing on the fluorescent screen at magnifications from 1500 to 50,000 times using an accelerating voltage of 50 KV.The EMU-3 type electron gun assembly consists of a V-shaped tungsten filament for a cathode with a thin metal threaded cathode shield and an anode with a central aperture to permit the beam to course the length of the column. The cathode shield is negatively biased at a potential of several hundred volts with respect to the filament. The electron beam is formed by electrons emitted from the tip of the filament which pass through an aperture of 0.1 inch diameter in the cap and then it is accelerated by the negative high voltage through a 0.625 inch diameter aperture in the anode which is at ground potential.

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Principles of Low-Vacuum SEM

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100131152 ◽

1992 ◽

Vol 50 (2) ◽

pp. 1304-1305

Author(s):

Klaus-Ruediger Peters

Keyword(s):

New Technologies ◽

High Vacuum ◽

Optical Microscope ◽

Specimen Surface ◽

Electrical Field ◽

Gaseous Environment ◽

New Information ◽

Gas Molecules ◽

New Interactions ◽

Gas Pressures

Only recently it became possible to expand scanning electron microscopy to low vacuum and atmospheric pressure through the introduction of several new technologies. In principle, only the specimen is provided with a controlled gaseous environment while the optical microscope column is kept at high vacuum. In the specimen chamber, the gas can generate new interactions with i) the probe electrons, ii) the specimen surface, and iii) the specimen-specific signal electrons. The results of these interactions yield new information about specimen surfaces not accessible to conventional high vacuum SEM. Several microscope types are available differing from each other by the maximum available gas pressure and the types of signals which can be used for investigation of specimen properties.Electrical non-conductors can be easily imaged despite charge accumulations at and beneath their surface. At high gas pressures between 10-2 and 2 torr, gas molecules are ionized in the electrical field between the specimen surface and the surrounding microscope parts through signal electrons and, to a certain extent, probe electrons. The gas provides a stable ion flux for a surface charge equalization if sufficient gas ions are provided.

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Analysis of Characteristics of LED Lamps with T8 Bulb by Various Manufacturers

Light & Engineering ◽

10.33383/2018-112 ◽

2019 ◽

pp. 82-87

Author(s):

Nina P. Nestyorkina ◽

Olga Yu. Kovalenko ◽

Yulia A. Zhuravlyova

Keyword(s):

Supply Voltage ◽

Luminous Flux ◽

Supply Network ◽

Operational Characteristics ◽

Nominal Voltage ◽

Electric Parameters ◽

The Moment ◽

Colour Rendering

The article analyses the operational characteristics of 10W LED lamps with T8 bulb manufactured by ASD (Russia), Smartbuy (Taiwan), and VOLPE (PRC) and 18W FL with T8 bulb manufactured by PHILIPS (Poland) including the dependence of these lamps on the supply voltage. The results of measurements show that: a) the period of stabilisation of electric parameters and luminous flux of LED lamps does not cause discomfort of illumination unlike the said FL, the luminous flux of which at the moment of switching on is 70 % of the nominal value, which is reached after 13 minutes; b) with nominal voltage of supply network, the value of luminous flux of 10W ASD LED-T8R-STD LED lamp (Russia) is 6 % less than the declared one, and that of Smartbuy SBL-T8-10-64K-A (Taiwan) and VOLPE LED-T8-10W/DW/G13/FR/FIX/N (PRC) is even less; c) the general colour rendering index of all studied LED lamps is less than the declared one (72 instead of 80); d) the flicker index of all studied LED lamps does not exceed the declared value of 5 %; e) the characteristics of LED lamps almost do not depend on changes of the supply voltage within the range of ±10 %. The recommendations regarding the application of the studied LED lamps are given.

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Dependence of Current Harmonics of Greenhouse Irradiators on Supply Voltage

Light & Engineering ◽

10.33383/2019-024 ◽

2020 ◽

pp. 85-88 ◽

Cited By ~ 1

Author(s):

Nadezhda P. Kondratieva

Keyword(s):

Mathematical Models ◽

Supply Voltage ◽

Harmonic Distortion ◽

Feasibility Studies ◽

Power Losses ◽

Voltage Level ◽

Supply Networks ◽

Current Harmonics ◽

Cable Lines ◽

Harmonic Composition

The article describes the results of the study concerning the effect of the voltage level on current harmonic composition in greenhouses irradiators. It is found that its change affects the level of current harmonics of all types of the studied greenhouse irradiators. With decrease of nominal supply voltage by 10 %, the total harmonic distortion THDi decreases by 9 % for emitters equipped with high pressure sodium lamps (HPSL), by 10 % for emitters with electrode-less lamps and by 3 % for LED based emitters. With increase of nominal supply voltage by 10 %, THDi increases by 23 % for lighting devices equipped with HPSL, by 10 % for irradiators with electrode-less lamps and by 3 % for LED based emitters. Therefore, changes of supply voltage cause the least effect on the level of current harmonics of LED based emitters and then the emitters with electrode-less lamps. Change of the level of supply voltage causes the greatest effect on the level of current harmonics of HPSL based irradiators. Mathematical models of dependence of THDi on the level of supply voltage for greenhouse emitters equipped with LED, electrode-less lamps and HPSL lamps were formulated. These mathematical models may be used for calculations of total current when selecting transformers and supply cable lines for greenhouse lighting devices, for design of new or reconstruction of existing irradiation systems of greenhouse facilities, and for calculation of power losses in power supply networks of greenhouse facilities during feasibility studies for energy saving and energy efficiency increasing projects.

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Interactions of Ge Atoms with High- ê Oxide Dielectric Surfaces

MRS Proceedings ◽

10.1557/proc-879-z3.23 ◽

2005 ◽

Vol 879 ◽

Cited By ~ 1

Author(s):

Scott K. Stanley ◽

John G. Ekerdt

Keyword(s):

Oxide Layer ◽

Photoelectron Spectroscopy ◽

Chemical Vapor ◽

Temperature Programmed Desorption ◽

Tungsten Filament ◽

X Ray ◽

Dielectric Surfaces ◽

Temperature Programmed ◽

The Stability ◽

Ge Nanocrystals

AbstractGe is deposited on HfO2 surfaces by chemical vapor deposition (CVD) with GeH4. 0.7-1.0 ML GeHx (x = 0-3) is deposited by thermally cracking GeH4 on a hot tungsten filament. Ge oxidation and bonding are studied at 300-1000 K with X-ray photoelectron spectroscopy (XPS). Ge, GeH, GeO, and GeO2 desorption are measured with temperature programmed desorption (TPD) at 400-1000 K. Ge initially reacts with the dielectric forming an oxide layer followed by Ge deposition and formation of nanocrystals in CVD at 870 K. 0.7-1.0 ML GeHx deposited by cracking rapidly forms a contacting oxide layer on HfO2 that is stable from 300-800 K. Ge is fully removed from the HfO2 surface after annealing to 1000 K. These results help explain the stability of Ge nanocrystals in contact with HfO2.

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