Electrostatic Accelerator for Electrons

Abstract

An account is given of the design and operation of five electrostatic accelerators constructed to supply an urgent radiographic need of the Navy. Each generator is housed in a steel tank 4.5 feet in diameter and 10 feet long, the insulating medium being gas at 200 pounds gauge pressure. The x‐ray generators are rated at 2‐million volts but were frequently operated at somewhat higher potentials. Tests were made with various insulating media, including air, nitrogen, Freon, and sulfur hexafluoride. With a 3‐foot extension to tank and insulating column and without a vacuum tube, a potential of 5.6‐million volts was attained with sulfur hexafluoride. Both continuously pumped and sealed‐off x‐ray tubes were used. These were supplied by the Machlett Laboratories, Inc., following a cooperative development. The use of focal spots only .01 inch in diameter made possible radiographs of extremely high definition. Target currents up to 300 microamperes produced in this voltage range an x‐ray output of great intensity and penetration.