. Elementary and dental radiography / by Howard Riley Raper . est back up for dental work is about 5 inches. From the foregoing it will be seen that any coil smaller than onewith a 7 or 8-inch spark gap could not well excite a high tube, and thatat least a ten-inch coil is necessary to light a very high tube. It seems,too. that any coil with a spark gap wider than eight or ten inches is need-lessly large. The coils with the long spark gaps are. however, seldomable to throw a fat, fuzzy spark farther than eight or ten inches. Thethrowing of a thin, blue spark a greater distance is simply incide
. Elementary and dental radiography / by Howard Riley Raper . est back up for dental work is about 5 inches. From the foregoing it will be seen that any coil smaller than onewith a 7 or 8-inch spark gap could not well excite a high tube, and thatat least a ten-inch coil is necessary to light a very high tube. It seems,too. that any coil with a spark gap wider than eight or ten inches is need-lessly large. The coils with the long spark gaps are. however, seldomable to throw a fat, fuzzy spark farther than eight or ten inches. Thethrowing of a thin, blue spark a greater distance is simply incidental and 44 ELEMENTARY RADIOGRAPHY without practical usefulness. Thus an eight or ten-inch coil may be aspowerful as one with an eighteen or thirty-inch spark gap; that is,capable of forcing as high a milliamperage through a high tube. If,however, a coil can force any kind of a spark at all through from eighteento thirty inches of atmosphere, we may be sure it will send a high milliam-perage through a good radiographic tube, or, what is the tubes equivalent. Fig. 41. The X-ray tube connected with the induction coil. in resistance, six or eight inches of atmosphere. It is so well understoodto-day that the coil with the very wide spark gap is not necessarily morepowerful, that manufacturers are making practically all of their coilswith from an eight to a twelve-inch spark gap, then rating them ac-cording to the milliamperage they can force through this resistance. To light a tube well a coil should be capable of giving a fat, fuzzyspark, the distance of the parallel spark which the tube backs up. The tube thus far described is the simplest form of X-ray tube, andno longer in general use. Next in simplicity is the bi-anodal tube. (Fig. 43-) When the two anodes are connected, as in Fig. Bi-anodal 43, the positive terminal may be attached to either Cubts. anode or assistant anode, preferably the anode. The advantage of the assistant anode is a matter on which authorities have widely
Size: 1726px × 1448px
Photo credit: © Reading Room 2020 / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., book, bookauthorraperhowardriley, bookcentury1900, bookdecade1910
