“SHOOTING” AT ATOMS

Evening Star, Issue 22106, 13 August 1935, Page 12

“SHOOTING” AT ATOMS

SUPER-GIANT TUBE DESCRIBED One year’s research in the building of a super-giant vacuum tube able to withstand terrific pressure set up in Technology’s 10,000,000-volt electrostatic generator, was described by Dr Karl T. Compton, president of Massachusetts Institute of Technology, before directors of the Research Corporation.

‘Knowing that ordinary vacuum tubes would be blown to bits by the firkt, flash-over from the poles of Tech’s “atom gun,” engineers under the direction of Dr Robert J. Van de Graaff have designed and nearly completed a great cylinder of papier mache, as strong as steel and capable of swallowing several dozen ordinary sized X-ray tubes. Outlined by Dr Compton, the building of such a hollow tube, one foot in diameter, 14 feet long, has been a scientific problem as difficult as the original design of the generator. Meanwhile, it was revealed that the generator itself has undergone improvement. Accurate voltage and current controls, as well as vibration eliminators, have been installed. With the completion of preliminary tests early in June, experiments in atomic disintegration were expected to begin. The tube, when finished, will consist of five identical units, joined end to end and sealed to metal caps at the two extremities. Through one end will be loosed the beam of proton particles, invisible bullets; through the other will appear automatic targets. The hollow tube is designed for rapid pumping out of air, Dr Compton told the directors, and it is provided internally with a series of specially built metal shields to hold the beam of electrified particles accurately in focus and distribute voltage along the tube in the most advantageous manner. In operation, the protons are fed into the magazine end of the tube like cartridges on a machine-gun belt. The kick is administered by the electrical output of the generator, so that a steady stream of particles is directed on atom targets made of thin sheets of various metals at the muzzle end.

An important development resulting from investigations already carried out with the generator, was the discovery that very penetrating X-rays up,. to 700,000 volts could be gained by coupling the Van de Graaff belt generator with a modified Lauritsen X-ray tube. The advantages of such a hook-up over previous X-ray outfits, Dr Compton asserts to be demonstrated in cheapness, simplicity of construction, ease and accuracy of voltage and current control; and most important of all, the entire current at maximum voltage is used to produce X-rays.