Röntgen rays and electro-therapeutics - with chapters on radium and phototherapy (1910) (14735105566)

Identifier: rntgenrayselectr00kass (find matches)
Title: Röntgen rays and electro-therapeutics : with chapters on radium and phototherapy
Year: 1910 (1910s)
Authors: Kassabian, Mihran Krikor, 1870-1910
Subjects: Electrotherapeutics X-rays Phototherapy Radiology Radiotherapy
Publisher: Philadelphia & London : J.B. Lippincott Company
Contributing Library: Francis A. Countway Library of Medicine
Digitizing Sponsor: Open Knowledge Commons and Harvard Medical School



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ent does notinstantly assume its maximumvalue. It takes an appreciabletime to rise to the current valueset by the resistance of the cir-cuit. This gradual rise of thecurrent is due to the presenceof the self induction of the cir-cuit, the largest percentage of which exists in the primary coil. Duringthe time that this self-induction current is rising in the primarycircuit, a magnetic field is being established about the primary wind-^iug. The strength of this magnetic field is at all times directly jjro-portional to the primary current. It is, therefore, zero at the time thatno current flows, and a maximum when the current has stopped rising.This magnetic field embraces the secondary coil as well as the primary.While the primary current is rising and the magnetic field is growing, avoltage is produced in the secondary coil by the expansive lines of mag-netic force, which voltage tends to produce a current in the secondarycoil opposite in direction to that flowing in the j)rimary. Fig.
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-Diagram illustrating the principles of in-duction. (After Donath.) THE EONTGEN EAY APPARATUS. 155 This current, induced at this time, is of low voltage and is not thecurrent desired in the X-ray tube. It is the inverse discharge whichtends to blacken the tubes and lower the vacuum at the time of therunning of the tube. When the interrupter opens the primary circuit, the primary cur-rent suddenly stojis, and at the same time the magnetic field collapses,inducing a very high voltage in the secondary coil. This tends to pro-duce a current in the secondary coil in the same direction as the currentflowing in the primary. B. The Construction of the Induction Coil. 1. The Primary Coil.—The first requirement in the construction ofan X-ray induction coil consists in arranging into a cylindrical bundlemany equal lengths of finely annealed charcoal iron wire, and in windingaround this core, several layers in thickness, a stout insulated (pri-mary) wire so arranged as to have terminals at one