The principal piece of equipment is the electron diffraction tube (EDT). It is essentially a 7" cathode ray tube with an added fixture to support the crystalline targets of aluminum and graphite. The electron gun assembly in the neck of the tube accelerates and focuses the electron beam. The deflection plates allow the beam to be directed onto the different types of target material and the diffraction pattern is then displayed on the face of the tube. The targets are permanently sealed into the evacuated tube. The tube is mounted in a box with a transparent top so that the structure of the tube, the targets, and the electrical connections are easily seen. The electrical controls for the tube are in a separate power supply cabinet. These include controls for the accelerating voltage, beam intensity, focus, and horizontal and vertical position. Also included are meters to indicate the target current and the accelerating voltage.