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The transepithelial electrical potential difference across rat rena proximal tubule was reinvestigated, using improved techniques. To diminish tip potential artefacts the microelectrodes were filled with HCO3-Ringer's solution instead of 3 molar KCl. The error of the potential measurements with HCO3-Ringer's microelectrodes was tested and was found to be ≤0.5 mV. A significant electrical potential profile was detected along the proximal tubular lumen under free flow. From near zero at the glomerulum the potential difference rose to −1.5 mV, lumen negative, in the first tubular loop at approximately 0.1 to 0.3 mm of tubular length. It decreased then rapidly, changed sign and attained a maximum of ca. 2.0 mV, lumen positive, at 1 mm of tubular length, after which it declined gradually to +1.6 mV in the last accessible loop. The mean of 85 punctures in intermediate and late loops was+1.8, S.D.±0.33 mV, range+1.0 to+3.2 mV. On the basis of perfusion experiments described in the subsequent paper, the lumen-negative potential difference across early loops can be explained as an active transport potential. It is caused by the presence of glucose and amino acids in the glomerular filtrate, which increase the rate of active Na+ absorption over that of active HCO3 − absorption. The lumen-positive potential difference in intermediate and late loops is explained as the sum of a membrane diffusion potential arising from the shift in intratubular Cl− and HCO3 − concentrations and a small lumen-positive active transport potential from H+ secretion/HCO3 − absorption.

Recently it has been pointed out that considerable instabilities can occur in MOS devices under negative voltage bias at room temperature. These instabilities are observed by appling at room temperature a voltage to the gate of an MOS device, cooling under this voltage bias to 77°K and subsequently measuring the CV curve or the threshold voltage with the applied voltage bias as parameter. The instabilities are due to the generation of positive charges in the oxide and cause negative voltage shifts. The generation of positive charges appears to be due to two types of centres (type 1 and type 2). Whereas the charge in the type 2 centres is stable at 77°K, the charge in the type 1 centres disappears at 77°K as soon as free electrons are present at the surface. Furthermore there is an increased fast interface state density, which is closely related to the positive charge in the type 2 centres. In this paper the charging of both centres is described in terms of a thermally assisted tunnelling process. In this way the observed time and temperature dependencies of the charging are explained and activation energies are determined. A model is presented that explains among other things the different discharge behaviour of the type 1 and type 2 centres.

This paper emphasises the arbitrary nature of the scalar potential in the expression for the electric field in a quadrupole mass filter and indicates that forms other than the commonly used combined d.c. and sinusoidal excitation may have theoretical and practical advantages. In particular it is shown that when a rectangularly time-varying function is chosen for this potential the device is freed of some of the technological limitations which hinder its usefulness in high precision applications. Specifically, it is noted that the need to maintain the ratio of two voltages constant is replaced by the requirement of keeping timing parameters steady, the latter being technologically easier. An electronic control unit based upon rectangular excitation is described and results obtained using it are presented. In particular a resolution of 230 has been achieved using a rectangular waveform of 1 MHz repetition rate with a peak-to-peak magnitude of about 80 V. It is shown that rectangular excitation also offers advantages in simulating the operation of the device on a digital computer since analytical solutions to the corresponding governing equations are available. A model based upon this is described and the results so obtained compare well with experimental values, thus indicating the validity and usefulness of the model in investigations of device performance.

In this paper we consider a model describing the formation of a plasma sheath in the neighbourhood of a plane absorbing conducting wall. Expressions are derived for the electric potential in the plasma and for the ion and electron densities. The validity of the model is restricted to cases in which the wall potential is monotonic in time

For pt. I see ibid., vol.7, no.5, 572 (1974). The general theory of the scattering of two particles in a time-dependent external field, presented in paper I, is applied to the case of two point particles with internal structure which interact through a potential with matrix representation (Vkl(r)). Under suitable, quite general, conditions upon the l2 operator bound mod V(r) mod of (Vkl(r)) the existence of the wave operators Omega +or-(s) is proven for two field configurations. The first is that of a spatially homogeneous time-dependent field, whereas in the second case the field is inhomogeneous but localized in space. Some attention is paid to the problem of the existence of differential cross sections and their relation to the scattering operator S(s)= Omega *+(s) Omega -(s).

High-impulse current and voltage measurement in high-voltage technology and plasma physics is generally accompanied by high-level electromagnetic interference. This paper gives an analysis of various avenues of conducted and radiated interference entry showing that cable braid and cabinet currents represent major source of interference. A better understanding of interference propagation leads to the systematic evaluation of counter measures which can be undertaken.

The one-photon self-energy radiative level shift for an electron in a Coulomb potential is evaluated numerically for the 1S 1 2 state. The evaluation is done for values of the nuclear charge Z = 10, 20,…, 110. The errors in the values obtained are estimated to be less than 0.1 %. The results are compared with the results of previous calculations. The evaluation is based on the expressions given in the preceding paper.

It is assumed, following Devonshire, that the ferroelectric behavior of BaTi${\mathrm{O}}_{3}$ arises because of the Lorentz correction, leading to a vanishing term in the denominator of the expression for dielectric constant. If the polarizability varies slowly with temperature, the temperature variation of dielectric constant follows. This temperature variation is assumed to come from that part of the polarization resulting from the displacement of the Ti ion, in a field whose potential energy has fourth-power as well as second-power terms in the displacement. The main object of this paper is to compute the Lorentz correction exactly, not assuming spherical symmetry, but taking account of the precise crystal structure. When this is done, it is found that the Ti ions, and those oxygen ions which are in the same line with them, the line being parallel to the electric field, exert very strong fields on each other, the resulting local field at the Ti ion being much greater than if computed on the assumption of spherical symmetry. This enhanced field makes it clear that even a relatively small ionic polarizability for the Ti ions will be enough to lead to ferroelectricity. The polarization of the Ti ions is however an essential feature of the theory; if they are not polarized, the Lorentz correction is profoundly modified, leading almost exactly to the value given by the approximate theory assuming spherical symmetry, and not resulting in ferroelectricity. Detailed formulas are given for comparison of the present theory with Devonshire's results, so that the present methods can be incorporated in his treatment of the effect of elastic strain energy on the stability of the various phases below the Curie point.

In electron impact studies, the difference between the ideal ionization probability curve which would be obtained with monoenergetic electrons and the experimental curve produced with a certain energy distribution is usually interpreted using the Maxwellian distribution of thermally emitted electrons and assuming that the electronic space charge and accelerating potential do not modify the energy distribution. Several recent papers (e.g. Hartwig and Ulmer 1963) mention contrarily that there is a redistribution of energy after a relaxation time. It will be shown that the influence of this redistribution of energy on ionization efficiency curves is different for different ion sources. It devolves that several instrumental effects can be explained, and that the electron energy distribution cannot be simply deduced from the sharpness of the discontinuities in the ionization efficiency curve.

In this paper experiments performed with the loop anode gas flow counters are discussed. Experiments have been performed to study the dependence of threshold potential with the variations in (1) source-anode distance and (2) size of the loop. The results obtained with the variations in loop size indicate that there exists an optimum loop size for the minimum of the threshold potential. With a cylindrical chamber optimum radius of the loop obtained is r /3.33 ( r = radius of the counter). A systematic analytical investigation of the occurrence of the optimum loop size gives loop radius to be r /2.67. Another set of experiments is performed to reduce the difference between the results obtained between experimental observations and that of analytical investigation in which spherical counter is used so as to have a closer approach to the assumptions made in the analytical investigations. The results obtained give optimum loop radius to be r /2.80. For the sake of interest loop is replaced by a thin copper disc. The variations in disc size do not indicate occurrence of any optimum disc size so as to give the minimum of the threshold potential.

Previous investigations have shown that the characteristics of shallow diffused junctions frequently exhibit important departures from those predicted by the ordinary solutions of the diffusion equation. These characteristics depend on the details of diffusion processes and play an important, but not completely understood, role in establishing detector quality. For example, the resolution loss associated with the junction deadlayer is generally greater than that predicted by simple statistics. This paper reports the results of a series of investigations undertaken for the purpose of optimizing the properties of detector junctions. Junctions studied have ranged in depth from 0.75 micron to several angstroms (estimated). Diffusion methods and junction structure are discussed. In addition, a rapid method for determining the details of junction structure by electronic scanning is described.

In two dimensional problems with the current flow in only one direction, the magnetic field can be solved by computing a scalar potential or one component of the vector potential. The general formulation for three dimensional solutions, including nonlinearities, is more complex and requires all three components of the vector potential as well as a scalar potential for the description of the fields. It is the purpose of this paper to present a general systematic formulation at low frequencies in terms of potential functions for three dimensional numerical solutions of the nonlinear electro-magnetic field problems that include either nonlinear magnetic materials or nonlinear electric materials. Special cases of the magnetostatic as well as eddy-current problems are discussed.

The correct potential in the effective mass equation should be the difference of the potential of a donor in the solid and that of an atom of the semiconductor host crystal. In the present paper such a difference potential is constructed for the central-cell region (defined by a sphere of radius of half the nearest neighbor distance), by making use of the Thomas-Fermi statistical theory, and considered as a perturbation to the potential (a simple Coulomb potential shielded by the static dielectric constant of the semiconductor) of the uncorrected theory. Using first-order perturbation theory the energy corrections are computed and the ground state energies of P, As, Sb and Bi in Si and Ge are found to be (the minus signs are not denoted) 31, 35, 39,45 meV and 8·9, 9·3, 9·6, 10.0 meV, respectively, representing a definite improvement over the values of 29 meV and 9.2 meV which were predicted for all donors in Si and Ge, respectively, by the uncorrected theory. The possible sources of the still remaining discrepancies between theoretical and experimental values are discussed and attributed partly to effects outside of the central-cell region and partly to approximations involved in the present treatment that resulted in obtaining a lower limit for the size of the corrections.

In this paper it is shown that the extraction efficiency in a synchrocyklotron can be increased considerably by selecting proper values for the internal circulating beam parameters. A good energy homogeneity and a high microscopic duty cycle can be achieved simultaneously. A calculation for some relevant radial amplitudes and energy gains/turn gives the energy diagram in fig. 11. From this it can be found that, if the internal beam is composed of 0.4 - 0.6 cm incoherent radial amplitudes and if the useful acceleration voltages are 7.2 - 10.6 kV, the gross extraction efficiency is 40 % for an energy spread of 300 keV. The duty cycle will be about 20 %. These results are valid if the vertical amplitudes are small so that the median plane motion program is correct.

As a pair of gears is loaded, the minimum oil-film thickness between the gear teeth decreases and can approach a magnitude equal to the magnitude of the surface roughness. Metal-to-metal contact then occurs between the microscopic peaks on both mating teeth surfaces. Therefore, the minimum thickness of the film separating the mating teeth surfaces may be considered as one of the criteria of capacity for a gear drive. A testing technique that was developed for measuring oil-film thickness between loaded gear teeth while running is presented in this paper. The voltage drop across a thin oil film that is required to cause an electrical discharge was used to determine the oil-film thickness. A specially designed machine containing a planetary gear train was used in these experiments. The relationships between the minimum oil-film thickness and the load transmitted by the gearing under certain conditions were determined using this method.

In the theory of diffusion of electrolytes the following assumptions are frequently made: (i) the electrolytic solution is electrically neutral everywhere, (ii) the ionic concentrations and the electric potential all depend on a single Cartesian coordinate as the only space variable. Often the electric potential of the solution is determined on the basis of the Poisson equation alone, disregarding any other relation between this potential and the ionic concentrations. Since the Poisson equation only represents a condition which the potential fulfills, the use of this equation alone may lead to error unless the explicit relation for the potential involving a space integration of ionic concentrations is also taken into account. But if this relation is used the Poisson equation becomes redundant and, more important, assumptions (i) and (ii) appear unacceptable, the former because it leads to a zero electric potential everywhere, the latter because it is mathematically incorrect. The present paper is based on general equations of diffusion of ions, excluding the Poisson equation. These equations form a system of nonlinear integrodifferential quations whose number equals the number of ionic species present in the solution. It appears that when all ions are distributed symmetrically around a point all functions related to the above system of equations can be made dependent on a single space coordinate: the distance from the center of symmetry. Two methods of successive approximations are given for the solution of the equations in the case of spherical symmetry with limitation to the steady state. These methods are then applied to the study of the distribution of ionic concentrations and electrical potentials inside a cell of spherical shape in equilibrium with its surroundings. These methods are rapidly convergent; exact theoretical values of the electric potential are calculable on the boundary of the cell. It appears that the potential at the center of the cell is not more than ∼50% higher than at its boundary and that variation of concentration inside the cell is not very large. For instance, with 100 mV on the boundary the ionic concentration there is about four times higher than at the center. Calculations show that extremely small amounts of electricity are sufficient to account for the electric potentials currently observed. In a cell of 100 micra diameter an average concentration of only 10−14 mole/cm3 of a monovalent ion would be sufficient to give 1 millivolt on the boundary. This concentration is directly proportional to the voltage and inversely proportional to the square of the cell diameter. Most of the numerical results given above are obtained by considering only those ions whose electrical charge is not compensated for by ions of an opposite sign. The total concentrations may be much higher than those quoted. The theory does not take into account possible effects of structural heterogeneities which may exist in the cell, particularly of various phase boundaries. An incidental result shows that the Boltzmann distribution function in the form employed in modern theory of electrolytes is fundamentally a consequence of the mathematical theory of diffusion alone. It is pointed out, however, that Boltzmann distribution is not always compatible with the definition of the electric potential.

This paper describes a high voltage pulse generator developed to deflect the beam of the 184-inch cyclotron at Berkeley, California. The apparatus develops a deflecting potential of 200 kilovolts that rises from 10% to 90% of peak value in 0.1 microseconds. The unit employs two similar 100 kilovolt water cooled pulse transformers connected symmetrically about ground to the electric deflector bars. Water-cooled General Electric pulse capacitors are discharged through the two turn primary windings of the pulse transformers by triggering a battery of 16 paralleled Kuthe 5022 hydrogen thyratrons. Output voltages are developed across the 17 turn secondary winding of the pulse transformer. The transformer is mounted in an oil filled lucite case that provides both insulation and compact design.