CATHODE RAY TUBE

Hokitika Guardian, 31 January 1927, Page 4

CATHODE RAY TUBE

SEW IiXPEimiE.NTS. (By Science Service). SCHKNECTADY, N Y.. Dee. U. A super-power cathode ray tube, which will take much higher voltages than the tube which he demonstrated recently at the Fraitklyn Institute, in Philadelphia, and which has attracted considerable scientific attention, is now planned by Dr \Y. D. Coolidge. assistant director ol the General Itleeti ic Company’s research laboratory. !he new form of the tube is described by |)r Coolidge in an article in the December issue ol the “Journal ol the Franklin Institute,” which is about to appear.

" Briefly, the method which he proposes to use is to ‘‘cascade” two or more tubes, the rays from one being led into another, which speeds them up still further, and increases their range. The cathode rays are rapidly moving electrons, small particles' of elect i iciti. moving with speeds ot a hundred thousand or more miles a second. These electrons start from a small electric light filament from which they come at speeds of merely a few miles a second. By building larger tubes, it will lie possible to increase the voltage to a certain limit, hut when too much power is apnliod to a single tube the cathode itself is bombarded by positive rays, which move in opposite directions to the cathode or negative rays. This introduces troublesome effects. By arranging two or more tubes toother so that the nickel window at the end of the tube, from which t h" rnvs ordinarily emerge info the open air. acts as the cathode of the next tn.be. they are already moving at great speed when they leave the lirst tube, and when the same voltage is applied to

the second tube they are still further accelerated. The window between the two tubes may be made thick enough so that it passes the cathode rays going in one direction, but stops the positive rays .going the opposite way. as t oriv are less penetrating. Another advantage of the multiple tube over a single very large one is that it is much easier to supply for instance four tubes with 230,000 volts each, than one tube with a million volts. Dr Coolidge says that he will try out this arrangement of the tubes as soon as the development of-the single tuln’ has been pushed to as high a voltage as possible.