http://www.computed-tomography.com Just another WordPress weblog Mon, 21 Dec 2009 17:13:51 +0000 http://backend.userland.com/rss092 en Thus, the nature of the secondary winding must be decided  according to the balance of those two factors deemed most  suitable for the work to be undertaken. The relation is not  really so simple as here stated, other factors complicating it;  but discussion of those is not essential to a ... http://www.computed-tomography.com/x-ray/chapter-3-part-21/ Thus, in the secondary circuit is set up a series of currents  alternating in direction, their periodicity depending upon the  rate of interruption of the primary current.  The inductive effect is augmented by the presence of the  iron core, with its alternate magnetisations and demagnetisa-  tions, which are in effect ... http://www.computed-tomography.com/x-ray/chapter-3-part-20/ We will not describe details of construction, since those  vary somewhat, and are dealt with in a more or less lucid way  to suit the resistance of different X-ray tubes than does a  valve-tube. By screwing the point home till it touches the plate the  spark-gap may be abolished; by screwing ... http://www.computed-tomography.com/x-ray/chapter-3-part-18/ An adjustable spark-gap, as illustrated in Fig. 39, may  be interposed in the secondary circuit for the same purpose of  cutting out inverse currents, and is so used commonly with  static machines. For heavier currents, as from coils, this is  a somewhat noisy working arrangement; but such an arrange-  ment ... http://www.computed-tomography.com/x-ray/chapter-3-part-17/ A tube under such conditions is not reliable for photo-  graphic exposures, and rapidly suffers in quality in the  manner described in the section on 'Changes during To check off these inverse currents some arrangement is  frequently interposed in the secondary circuit between the  coil and the anode of the ... http://www.computed-tomography.com/x-ray/chapter-3-part-16-2/ The current sent from an induction-coil through an X-ray  tube consists of a rapidly recurring series of brief currents  induced in the secondary circuit in consonance with the  interruptions of the current sent to the coil from the inter-  rupter or break. This secondary current will depend initially  upon the ... http://www.computed-tomography.com/x-ray/chapter-3-part-16/ With 8 amperes passing, the break works on steadily with  a regular ' dick-dick' bruit, but on approaching 12 amperes  the sound becomes lower-pitched and laboured, denoting that  the coil cannot absorb or utilise the surge of current supplied  to it. We have said that a great potential spark-length is not  ... http://www.computed-tomography.com/x-ray/chapter-3-part-15/ Convert the E.M.F. of the current supplied to a voltage suit-  able for the X-ray tube. The degree of this function may be  appreciated when we note that to produce a 12-inch spark  across the discharging points of a coil requires a potential of  about 148,000 volts. This increase in ... http://www.computed-tomography.com/x-ray/chapter-3-part-14/ It is important that an electrolytic interrupter should be  connected correctly, the platinum to the positive pole of the  source. If connected otherwise, the platinum will gradually  Induction-coils have been already referred to in the intro-  duction to this chapter, and some of the conditions of their  working discussed. We ... http://www.computed-tomography.com/x-ray/chapter-3-part-13/ In action, and especially with heavy currents of high  pressure, electrolytic breaks are very noisy; so the whole cell  and attachments should be cased in felt, to deaden the sound,  and the break should be kept in a separate closed room where  possible. With heavy work the electrolyte becomes very soon ... http://www.computed-tomography.com/x-ray/chapter-3-part-12/