. Radiographie élémentaire et dentaire / par Howard Riley Raper . Figure 45. Montrant la manière de connecter la troisième borne de la bobine à la chambre de régulation. La chambre de régulation contient de l'amiante imprégné d'hydrate de sodium ou de potassium, par exemple. Lorsque le currentpasse dans la chambre de régulation, de la chaleur est créée, ce qui provoque la dissipation de gaz. Ces gaz réduisent le vide du tube, de sorte que le courant puisse passer directement de l'anode à la cathode. Lorsque le tube DE RADIOGRAPHIE élémentaire 48 refroidit complètement, en quinze à trente minutes, le
1668 x 1498 px | 28,2 x 25,4 cm | 11,1 x 10 inches | 150dpi
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. Elementary and dental radiography / by Howard Riley Raper . Fig. 45. Showing the manner of connecting the third terminal on the coil with the regulating chamber. The regulating chamber contains asbestos impregnated with somechemical, sodium or potassium hydrate, for examples. When the currentpasses through the regulating chamber, heat is created, which causes thechemical to give off gases. These gases lower the vacuum of the tube.so that the current may pass directly from anode to cathode. When the 48 ELEMENTARY RADIOGRAPHY tube cools thoroughly—in the course of fifteen to thirty minutes—thesegases are taken up again by the chemicals in the regulating chamber, and the vacuum rises again. Thus the vacuum of the tube may be toohigh when the tube is not in use, but can be lowered to the desireddegree. Ordinarily the tube-regulating spark gap should be three CATHODESTREAM. Fig. 4fi. Showing the direct X- nl tli cathode stream. to five inches. As the tube gets old the tube-regulating spark gap mustbe made shorter to obtain the same condition of tube. When the tube is properly hitched to the coil, and the movable armset for a high vacuum—to give a regulating spark gap of about fourinches—and the current turned on, practically all the current may at firstpass through the regulating chamber and jump the tube-regulating sparkgap. As explained, this lowers the vacuum, and in a few seconds thecurrent is passing from anode to cathode. All of the current may passdirectly through the tube now for a few seconds, but the passage of thecurrent from anode to cathode raises the vacuum and presently somecurrent will be seen to jump the gap for a while. And so on, just as thevacuum raises a little, it is immediately lowered by some of the currentpassing through the regulating chamber. X-RAY TUBES AND THE X-RAYS 49 Instead of the movable arm, a terminal tape and a th
