Concentric Coils Research Articles

Determining the index of a betatron field from the vector potential

Relations are derived for the determination of the field index from the vector potential measured with a set of concentric coils of constant length of winding or with a set of radially equidistant coils of constant number of turns. The method has been applied to the magnetic field of a 15 MeV betatron and gives the index with an accuracy of about 3%.

ANL superconducting magnets

A large-bore superconducting magnet system developed at Argonne National Laboratory has sustained a field of 67 000 gauss at the center of its innermost coil. An outcome of a two-year study of the properties of superconducting coils and wires at Argonne, the new system consists of three concentric coils, 18 inches, 11 inches, and 7 inches, respectively, in inside diameter. The magnets use a superconducting wire developed at Argonne and manufactured by Supercon and Westinghouse Cryogenic Systems Department, which was wound into cables at Argonne. The maximum energy stored in all three coils exceeds 600 000 joules.

The Calculation and Measurement of Axial Electromagnetic Forces on Concentric Coils in Transformers

The Calculation and Measurement of Axial Electromagnetic Forces on Concentric Coils in Transformers

Revising tests for transformer insulation

THE MARGINS obtained and the degree of co-ordination between transformers and other insulation in transmission systems depends largely on the possibilities inherent in the insulation design of the transformer. Recently some units have been designed which take full advantage of the impulse characteristics of insulating materials as compared to their 60-cycle strengths. These designs are core-form, or at least have concentric coils, and it is likely that they might be considered to have maximum impulse characteristics compatible with present 60-cycle test requirements. It is believed that these characteristics affect and should be given consideration in the setting of future required impulse levels and tests, and perhaps in the 60-cycle tests which are required.

Torque between concentric single-layer coils

Torque between concentric single-layer coils

Tables for the Calculation of the Mutual Inductance of Any Two Coaxial Single-Layer Coils

Absolute formulas for the calculation of the mutual inductance of coaxial solenoids, although they are required for work of the great precision necessary in absolute measurements, are not convenient for routine calculations. Series formulas, although simpler, are limited in the range of their convergence, thus requiring the choice of the proper formula for any given problem. The tables and formulas here presented enable the mutual conductance of any two coaxial solenoids whatever to be calculated from a single formula. Examples make clear that a five-figure accuracy may be attained with concentric coils and even with poorly coupled coils the error does not exceed a few parts in ten thousand.

Mechanical forces in transformers

In this paper a method of calculating the mechanical forces in transformers, based on mutual reactance between coils, is presented. A formula for the mutual inductance between coaxial solenoids is developed and from this expression the formula for the mechanical force between concentric cylindrical transformer coils is derived. The same method is followed to obtain the formula giving the mechanical force between individual coaxial coils. The method is checked by calculations of reactance of complicated arrangements of coils. Tables are given to facilitate calculations.

Mechanical Forces in Transformers

In this paper a method of calculating the mechanical forces in transformers, based on mutual reactance between coils, is presented. A formula for the mutual inductance between coaxial solenoids is developed and from this expression the formula for the mechanical force between concentric cylindrical transformer coils is derived. The same method is followed to obtain the formula giving the mechanical force between individual coaxial coils. The method is checked by calculations of reactance of complicated arrangements of coils. Tables are given to facilitate calculations.

Positive Ray Analysis of Lithium and Magnesium

Isotopes of lithium and magnesium have been determined by positive ray analysis, using the apparatus and method previously described in which the positive ray spectrum is determined by measuring the charge passing through a fixed slit into a Faraday cylinder as a function of the accelerating difference of potential keeping the deflecting magnetic field constant. The source of the rays was a small cylindrical anode containing the metal to be studied, which was heated by a concentric coil and bombarded by electrons. It was found that there are two isotopes of lithium with atomic weights 6 and 7, while magnesium has three isotopes with atomic weights 24, 25 and 26. The relative proportions of the isotopes of lithium varied with the conditions. For magnesium the relative numbers were 7: 1: 1.Compensation Method of Measuring Small Currents.---The current to be measured is balanced by the current through an ionization chamber, which is adjusted to equality by varying the width of the slit through which the ionizing beta rays pass.