ELECTRICAL BREAKDOWN IN ARGON AT ULTRAHIGH FREQUENCIES

1956 ◽  
Vol 34 (4) ◽  
pp. 395-397 ◽  
Author(s):  
A. D. MacDonald ◽  
J. H. Matthews
Keyword(s):  
Electric Fields ◽  
Electrical Breakdown ◽  
Resonant Cavities ◽  
Argon Gas ◽  
Pure Argon ◽  
Ultrahigh Frequencies ◽  
Made In

Measured values of breakdown electric fields in pure argon gas are presented. Measurements were made in two resonant cavities at a frequency of 2800 Mc./sec. and for pressures varying from 4 × 10−2 to 200 mm. of mercury. The present results are in agreement with those of Krasik, Alpert, and McCoubrey.

ELECTRICAL BREAKDOWN IN XENON AND KRYPTON AT ULTRAHIGH FREQUENCIES

1959 ◽  
Vol 37 (10) ◽  
pp. 1166-1170 ◽  
Author(s):  
H. M. Bradford ◽  
D. M. Fraser ◽  
G. F. O. Langstroth ◽  
A. D. MacDonald
Keyword(s):  
Electric Fields ◽  
Pressure Range ◽  
Electrical Breakdown ◽  
Resonant Cavity ◽  
Ultrahigh Frequencies

Breakdown electric fields have been measured in a resonant cavity for xenon and krypton gases in the pressure range of 0.05 to 100 mm of mercury, at a frequency of 2800 Mc/sec. Extensive precautions were taken to ensure gas purity.

scholarly journals Electrical tunability of terahertz nonlinearity in graphene

2021 ◽  
Vol 7 (15) ◽  
pp. eabf9809
Author(s):  
Sergey Kovalev ◽  
Hassan A. Hafez ◽  
Klaas-Jan Tielrooij ◽  
Jan-Christoph Deinert ◽  
Igor Ilyakov ◽  
...  
Keyword(s):  
Electric Fields ◽  
Quantitative Agreement ◽  
Terahertz Frequency ◽  
Frequency Range ◽  
Single Cycle ◽  
Terahertz Frequency Range ◽  
Third Harmonic ◽  
Accurate Design ◽  
Electronic Signal Processing ◽  
Ultrahigh Frequencies

Graphene is conceivably the most nonlinear optoelectronic material we know. Its nonlinear optical coefficients in the terahertz frequency range surpass those of other materials by many orders of magnitude. Here, we show that the terahertz nonlinearity of graphene, both for ultrashort single-cycle and quasi-monochromatic multicycle input terahertz signals, can be efficiently controlled using electrical gating, with gating voltages as low as a few volts. For example, optimal electrical gating enhances the power conversion efficiency in terahertz third-harmonic generation in graphene by about two orders of magnitude. Our experimental results are in quantitative agreement with a physical model of the graphene nonlinearity, describing the time-dependent thermodynamic balance maintained within the electronic population of graphene during interaction with ultrafast electric fields. Our results can serve as a basis for straightforward and accurate design of devices and applications for efficient electronic signal processing in graphene at ultrahigh frequencies.

THE BAND GAP ESTIMATION OF ZINC MANGANESE PHOSPHATE GLASSES

2008 ◽  
Vol 22 (12) ◽  
pp. 1265-1272 ◽  
Author(s):  
S. A. SIDDIQI ◽  
M. A. GHAURI ◽  
M. J. S. BAIG
Keyword(s):  
Electric Fields ◽  
Spectral Dependence ◽  
Transport Mechanism ◽  
Phosphate Glasses ◽  
Band Gaps ◽  
Spectral Energy ◽  
Charge Transport Mechanism ◽  
Optical Band Gaps ◽  
Manganese Phosphate ◽  
Made In

Zinc manganese phosphate glasses ( ZnO - MnO - P 2 O 5) of different compositions are synthesized. The optical band gaps are measured in the UV-VIS region. Photoconduction measurements are also made in the spectral energy range 1.5–6.2 eV. At various applied electric fields, the values of the energy band gaps have been deduced from the spectral dependence curves. Furthermore, the band gaps at zero applied voltage were also obtained for different compositions. The charge transport mechanism in these glasses is studied under the Mott's model.

ELECTROMAGNETIC FIELDS IN AN N‐LAYER ANISOTROPIC HALF‐SPACE

Geophysics ◽  
1967 ◽  
Vol 32 (4) ◽  
pp. 668-677 ◽  
Author(s):  
Douglas P. O’Brien ◽  
H. F. Morrison
Keyword(s):  
Magnetic Field ◽  
Experimental Data ◽  
Plane Wave ◽  
Half Space ◽  
Electric Fields ◽  
Field Measurements ◽  
Large Scatter ◽  
Tensor Impedance ◽  
The Magnetic Field ◽  
Made In

From Maxwell’s equations and Ohm’s law for a horizontally anisotropic medium, it may be shown that two independent plane wave modes propagate perpendicular to the plane of the anisotropy. Boundary conditions at the interfaces in an n‐layered model permit the calculation, through successive matrix multiplications, of the fields at the surface in terms of the fields propagated into the basal infinite half space. Specifying the magnetic field at the surface allows the calculation of the resultant electric fields, and the calculation of the entries of a tensor impedance relationship. These calculations have been programmed for the digital computer and an interpretation of impedances obtained from field measurements may thus be made in terms of the anisotropic layering. In addition, apparent resistivities in orthogonal directions have been calculated for specific models and compared to experimental data. It is apparent that the large scatter of observed resistivities can be caused by small changes in the polarization of the magnetic field.

Weyerhaeuser's Experience: Corrosion Resistance of Stainless Steel Overlays in Kraft Digesters

CORROSION ◽  
1961 ◽  
Vol 17 (6) ◽  
pp. 20-24
Author(s):  
C. L. Carns
Keyword(s):  
Stainless Steel ◽  
Corrosion Damage ◽  
Automatic Welding ◽  
Argon Gas ◽  
Design Changes ◽  
Weld Material ◽  
310 Stainless Steel ◽  
Time Work ◽  
Made In

Abstract Success with hand weld overlays of Type 310 stainless to repair corrosion damage in bottom cones of Kraft digesters at Longview, Wash., induced Weyerhauser to use Type 310 stainless steel to repair complete digester shells of five units in 1956. Automatic welding guns were used with argon gas. At Everett, seven more digesters were overlaid in much the same manner. Type 316 was used for work at Everett because, by the time work was begun, some failures had been noted in the upper parts of the units at Longview. Analysis showed that the original weld material was being diluted by the base metal in the ratio of 1 to 2. In an effort to reduce the amount of dilution experienced, alterations were made in the method of deposit on the upper shell of the final unit at Everett. The gun was tilted 20 degrees to normal to effect greater impingement on preceding beads. Weight of deposit was increased, and rate of feed of argon ^ gas also was increased to effect better shielding. The top four feet of the shell was given a double overlay. Tilting the gun did not materially improve the quality of the deposit. Double overlay produced a surface with an analysis close to that of the overlay wire. Reports of inspections in several zones of the digesters are given. Significance of pits in overlaid material of this kind is emphasized. Tests are being conducted using various types of weld overlay to find one more resistant. Some design changes were made in the digester. Impingement plates were installed to absorb erosive force of liquor and to provide cathodic protection to the overlay. 3.7.3, 9.6.6, 8.5.3, 6.2.5.

scholarly journals The scattering of hydrogen positive rays, and the existence of a powerful field of force in the hydrogen molecule

1922 ◽  
Vol 102 (715) ◽  
pp. 197-209 ◽  
Keyword(s):  
Electric Fields ◽  
General Scheme ◽  
Hydrogen Gas ◽  
Theoretical Interpretation ◽  
Scattering Medium ◽  
Hydrogen Atoms ◽  
Hydrogen Molecules ◽  
Nuclear Particle ◽  
Positively Charged ◽  
Made In

In view of the extremely important results obtained by Sir E. Rutherford and others from a study of the scattering of α -rays, it seemed worth while to investigate the scattering of particles moving with smaller velocities such as occur in the positive rays. The most interesting, because the simplest, are the rays of positively charged hydrogen atoms, which presumably consist simply of a nuclear particle, or proton. The experiments described in this paper were made in some cases with these rays, in others with the positively charged hydrogen molecules, systems consisting of two protons and one electron. The scattering medium was in all cases hydrogen gas. This was chosen largely for convenience, as the experimental arrangement is considerably simplified if the same gas is used to produce the rays and to scatter them, and also because, with the exception of helium, the molecule of hydrogen is the simplest known, and there seemed more hope of obtaining results which could be given a definite theoretical interpretation. The general scheme of experiment was to produce the rays in a discharge tube, analyse them by magnetic and electric fields in the ordinary way, cut off all except those of the kind required by a slotted diaphragm, pass the remainder through a chamber containing the scattering gas, and receive them in a Faraday cylinder arranged behind a slit of variable width. The experiment consisted in finding how the charge received by the Faraday cylinder varied with the width of the slit, when this was made wider than the geometrical “shadow” of the slot in the diaphragm. Any rays lying outside this “shadow” must have been scattered.

HIGH FREQUENCY GAS DISCHARGE BREAKDOWN IN NEON

1952 ◽  
Vol 30 (5) ◽  
pp. 565-576 ◽  
Author(s):  
A. D. MacDonald ◽  
D. D. Betts
Keyword(s):  
Kinetic Theory ◽  
Electric Fields ◽  
Cross Sections ◽  
Electrical Breakdown ◽  
Ionization Rate ◽  
Gas Discharge ◽  
Distribution Functions ◽  
Boltzmann Transport ◽  
Discharge Data ◽  
Confluent Hypergeometric Functions

Electrical breakdown of neon at high frequencies has been treated theoretically on the basis of the Boltzmann transport equation. Exciting and ionizing collisions are accounted for as energy loss terms in the Boltzmann equation and measured values of the ionization efficiency are used in the integral determining the ionization rate. Electrons are lost to the discharge by diffusion. The equations are treated separately for the cases in which the collision frequency is much less than or much greater than the radian frequency of the applied field. The electron energy distribution functions are expressed in terms of Bessel functions, confluent hypergeometric functions, and simple exponentials. The ionization rate and the diffusion coefficient are calculated using these distribution functions in kinetic theory formulas, and combined with the diffusion equation to predict breakdown fields. The theoretically predicted fields are compared with experiment at 3000 Mc. per sec. The breakdown equations, calculated from kinetic theory and using no gas discharge data other than collision cross sections, predict breakdown electric fields within the limits of accuracy determined by these cross sections over a large range of experimental variables.

scholarly journals Reduction of Electric Breakdown Voltage in LC Switching Shutters / Elektriskās Caursites Sprieguma Samazināšana Šķidro Kristālu Šūnās

2015 ◽  
Vol 52 (5) ◽  
pp. 47-57 ◽  
Author(s):  
G. Mozolevskis ◽  
A. Ozols ◽  
E. Nitiss ◽  
E. Linina ◽  
A. Tokmakov ◽  
...  
Keyword(s):  
Liquid Crystal ◽  
Electric Fields ◽  
Electrical Breakdown ◽  
Liquid Crystal Display ◽  
Threshold Value ◽  
Buffer Layers ◽  
Limiting Factors ◽  
Dust Particles ◽  
Crystal Layer ◽  
Liquid Crystal Layer

Abstract Liquid crystal display (LCD) industry is among the most rapidly growing and innovating industries in the world. Here continuously much effort is devoted towards developing and implementing new types of LCDs for various applications. Some types of LCDs require relatively high voltages for their operation. For example, bistable displays, in which an altering field at different frequencies is used for switching from clear to scattering states and vice versa, require electric fields at around 10 V/μm for operation. When operated at such high voltages an electrical breakdown is very likely to occur in the liquid crystal (LC) cell. This has been one of the limiting factors for such displays to reach market. In the present paper, we will report on the results of electrical breakdown investigations in high-voltage LC cells. An electrical breakdown in the cell is observed when current in the liquid crystal layer is above a specific threshold value. The threshold current is determined by conductivity of the liquid crystal as well as point defects, such as dust particles in LC layer, pinholes in coatings and electrode hillocks. In order to reduce the currents flowing through the liquid crystal layer several approaches, such as electrode patterning and adding of various buffer layers in the series with LC layer, have been tested. We demonstrate that the breakdown voltages can be significantly improved by means of adding insulating thin films.

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