A New High Potential X-Ray Tube

An attempt has been made to develop apparatus and methods of operation for generating and investigating x-rays in the region beyond 300 kv. A tube is described which was designed to operate with 1000 kva, one million volt, transformers available at the California Institute of Technology. The tube is built up of glass cylinders internally shielded against electronic bombardment. The pheonomenon of "cold emission" is utilized for obtaining the electrons, the full potential being applied between electrodes of suitable curvature placed close together, (1 to 2 cm). A preliminary report of the results is given. This includes oscillograms showing the pecularities of the current due to "cold emission" as well as the actual potential across the tube. Absorption measurements of the x-rays have been made with lead up to 2 cm thick and it is shown that secondary emission plays an important part in the photo-chemical action of these rays. Satisfactory operation has been obtained up to 750 kv