Toshiba (Austria)

Breakdown of transformer oil is affected not only by electrostatic field configurations, but also by many other factors. The latters make it difficult to predict break- down voltage from electrostatic field, as made for air and S F6 gaps. Alternatively, many experimenters tried to express the breakdown stress of oil as a function of stressed oil volume. But, results are limited to their respective electrodes.

The paper relates the voltage escalation due to repetitive reignition occurring when interrupting the inductive current by vacuum switches, and offers a new theory quite different from those recognized hitherto on the generating mechanism. It also shows that a CR Surge Suppressor is effective for suppressing the voltage escalation.

Approximate solutions of the effective mass Schrödinger equation for donor states in gallium phosphide are calculated by a variational method with a parameter γ= m ⊥ / m // . Comparison of the calculated energies of p -like states of donor with the experimental energy separations between several excited states from the “ two-electron ” recombination radiation of excitons bound to neutral donors by Dean et al. , determines the transverse mass m ⊥ =(0.21±0.01) m 0 and the longitudinal mass m // =(1.15±0.05) m 0 at the bottom of the conduction band in gallium phosphide.

This paper describes the breakdown characteristics of SF6 at pressures up to 15 kg/cm2 absolute at 20°C against power frequency, switching impulse and lightning impulse voltages in sphere and coaxial cylinder gaps.

This paper describes the breakdown potential gradient of sulphur hexafluoride (SF6) at pressures up to 4 kg/cm2 absolute against power frequency, switching impulse and standard impulse voltages in nearly uniform fields such as plane-plane, sphere- sphere, and coaxial cylinder electrode configurations. Electrode material, smoothness and polarity effect are also investigated for coaxial cylinders.

Potential gradient at the surface of the electrode is the most important factor in the breakdown of SF6 gas gaps as has been reported in the previous papers. 1, 2

A method is presented which calculates approximately the electrical torque in synchronous machine at multi-phase reclosing, neglecting subtransient saliency and electrical decrements. A new digital simulation program, with some examples of digital calculations, is presented in detail which is used to analyze the transient phenomena accompanying power swings at multi-phase reclosing, after multi open conductors following the fault.

Excitation functions for elastic scattering of protons on Ne 22 were studied at θ c.m. =56.9°, 92.6°, 125.7°, 140.8° and 151.3° in the energy range E p =0.94–4.2 MeV. The excitation function for protons inelastically scattered to the first excited state of Ne 22 was measured at θ lab. =139.1° above E p =2.1 MeV and the γ rays following them were observed below E p =2.1 MeV. A total of 75 resonances was observed corresponding to Na 23 levels between 9.7 MeV and 12.8 MeV. Several pronounced resonances are analysed using the single level approximation of the dispersion formula, and level parameters are assigned. The T =3/2 isobaric analogue states in Na 23 and Ne 23 are discussed.

A differential absorption pulsed dye laser radar for NO2, concentration measurement was developed. A special laser resonator, which generates two wavelengths alternately, was devised for this laser radar. NO2 concentration, as an air pollutant, was measured automatically using a mini-computer in Kawasaki for 30 hours. Averaging one thousand 75 pps repetition signal data made it possible to detect a concentration as low as 5 ppb in a 2 km round trip path.

Potential gradient at the surface of the electrode is the most important factor in the breakdown of SF6 gas as reported in a companion paper. Hence the breakdown voltage may be predicted from the potential gradient at the surface of the electrode with technically acceptable accuracy.

The paper describes principles of "sliced-level" type phase-comparison carrier relaying system which has several remarkable characteristics such as higher sensitivity and high speed tripping time.

The current density and the Hall coefficient of n -and p -type InSb were measured as a function of electric field, E , up to 1000 volt/cm in a transverse magnetic field, H , from 1000 to 6000 gauss at 77°K. In n -InSb, for H >2000 gauss, incoherent current oscillations with frequency of 20∼50 Mc/sec set in at E ≃100 volt/cm, which is smaller than the intrinsic “breakdown” field, simultaneously with the saturation of the “Hall” drift velocity, while, for H <2000 gauss, oscillations were only observed at E ≃200∼300 volt/cm (the “breakdown,, field). As the magnetic field is increased, the threshold electric field of oscillations decreases, at first, in proportion to the reciprocal of H , reaches a minimum at H ≃3500 gauss and increases with further increase of H . There seems to be optimum values of E and H for oscillations. Some discussions were made on a possibility of the instability of weakly ionized plasma due to the presence of a density gradient parallel to the current direction. In p -InSb, the threshold electric field of oscillations is nearly independent of magnetic field up to 6000 gauss and it is likely that the acoustic instability is the cause of oscillations.

As a basic knowledge of high-Cr-Ni-base superalloys, the precipitation hardening behaviors of 40Cr-Ni alloys containing various amounts of Al or Ti are studied experimentally. Their hardness, X-ray and microscopic examinations are made after various aging treatments at 700, 800 and 900°C. By the addition of Al or Ti, the duplex precipitation of γ′ or η and α-Cr is observed. Because of this duplex precipitation, for example, the hardness of 40Cr-3.8Al-Ni alloy increases to the maximum hardness of about Hv 680 in the aged condition from about Hv 200 in the solution-treated condition. These extremely high age-hardenabilities are analytically discussed from the viewpoints of γ′ phase hardening and α phase hardening.

In [1] and [2], Hironaka referred to the importance of an additive group scheme B Pn,P , which is associated with a point p in P n , in connection with the resolution of singularities in characteristic p > 0. Also he showed that if the dimension of B Pn,p is not greater than p , then it is a vector group.

For Ca 3 (PO 4 ) 2 :Cu phosphor, measurements of spectral distributions of luminescence, reflectivity and quantum efficiency, temperature dependence of luminescence intensity and decay constants are carried out. The one-dimensional configurational coordinate curves for the luminescence center in this phosphor are determined by analysing spectral data. Some characteristics expected from these curves are compared with the observed; the agreement in the absorption band width and the disagreement in the activation energy for nonradiative transition are obtained. The relations between one- and many-dimensional models are investigated and the cause for the above disagreement is attributed to the simplicity of the assumed model. Discussions are also made on the nonradiative transitions in this center.

The secondary emission yield is observed to decay very rapidly under electron bombardment especially during the exhaust process using oil diffusion pump. In this paper, factors affecting the decay, a method of remedy to make the decayed yield to recover, and effects of various gases and vapors on the yield are discussed. A major cause of the secondary yield decay is attributed to the deposition of amorphous carbon, which is produced on the dynode surface through the decomposition of hydrocarbon or carbon-containing gases by the electron beam. Heating the contaminated dynode at high temperatures in oxygen atmosphere for some period results in a recovery of the yield. Keeping the dynode at high temperatures during electron bombardment is effective in bringing about a marked decrease in the decay. From the data on the temperature dependence of the decay, the heat of adsorption of a gas which is considered to be the source of contamination, is calculated to be about 1.6 kcal/mole. N 2 , CO and CO 2 do not exert any harmful effects upon activated dynodes, while H 2 exerts somewhat harmful effects, and, particularly, electric discharge in H 2 should be avoided. The most unfavorable gas is the grease vapor. The process of contamination is briefly discussed.

Condon's formalism of the optical activity suggests the presence of a sort of surface current at the boundary of the optically active medium. In this paper is discussed the origin of this surface current in terms of the general conductivity tensor. The expression of the surface current for the arbitrary medium consists of two parts; one is expressed with the bulk conductivity tensor and corresponds to the magnetization current in Condon's formalism, while the other is related to the surface charge and reflects the surface property. The reflectivity calculated for a lossless isotropic medium shows that the normally incident linearly polarized light does not undergo optical rotation by reflection as is pointed out by some authors.

A simple method is described for measuring low rates of selective oxidation of Ag–Mg alloys at elevated temperatures when water vapor is used as oxidizing agent. It is found that the MgO layer builds up on the surface of the alloy according to a parabolic law over a range of the water vapor pressure from 7×10 -3 to 6×10 -2 mm Hg, and the oxide growth begins to follow a linear law rather than a parabolic law at a pressure of 1 mm Hg. In the region where the parabolic law holds, the growth of the oxide layer seems to be controlled by the diffusion of Mg through the layer. 20.7 kcal/mol is obtained as the activation energy of diffusion. Applyjng the transition state theory of gas-metal reaction, as developed by Gulbransen, the diffusion of Mg through the oxide layer is given by D (cm 2 /sec)=2.17×10 -9 exp (-20,700/RT).

Photoconductivity of CdS single crystals was measured at room temperature under argon ion laser excitation. For strong uniform excitation, photoelectron concentration reached a value independent of the excitation intensity and a fast-decay photoconductivity appeared. For strong surface excitation, a logarithmic variation of photoconductivity with excitation intensity was observed. These results are analysed on a two-recombination-center model; under strong excitation usual recombination center is completely occupied by hole and another center plays dominant role in recombination. Comparison between photoconductivities under uniform and surface excitations determines hole lifetime, ambipolar diffusion length and surface recombination velocity. Measurements of PEM effect and optical absorption induced by the excitation are consistent with the photoconductivity analysis. Characetristics of the recombination centers are quantitatively determined.

The temperature-dependence of rectifying action of silicon and iron pyrite detectors was measured between -183°C and 300°C. The maximum rectification ratio for Si-W detector occurs at about 60°C, while for some iron pyrites a kink appears at about -60°C in the rectification-ratio versus temperature curves, although we have no maximum in the measured range of temperatures. Mott's and Davydov's theories on the reetification are insufficient o explain these results. The author proposes a theory based on the tunnel effect of electrons through the upper part of a blocking layer. in which the calculation was made for the thickness 20 Å∼30 Å of the blocking layer. It is expected from our theory that there exists a critical temperature at which the inversion of rectification occurs and that the rectifylng action is a function of the thickness of layer and the conductivity of the crystal in bulk, The inversion of rectification at different places on the surface of the crystal can also qualitatively be explained by our theory.