High potential x-ray tube

An account is given of further development work on the high potential x-ray tube at the California Institute of Technology. Details of the construction of the tube and its housing are presented. The housing, which is a concrete structure erected on the floor of the high potential laboratory, makes it possible to operate and make observations at close range. The tube has been equipped with a hot cathode and a tungsten target, thus rendering it more suitable for spectrographic work. High speed cathode rays outside of the tube have been obtained by replacing the target by thin windows of mica or metal. Continuous operation is possible over a period of several hours at six hundred kilovolts and with a space current of three to four milliamperes. A comparison between different types of high potential x-ray tubes and of different methods of operation is contained in the discussion.