Electron beam current, profile and position monitor

Apparatus for monitoring a first and second electron beam travelling in opposite directions comprising:

• a. foil means having opposite surfaces of width w.sub.1 and length l.sub.1, where w.sub.1 is smaller than the electron beam cross-sections and l.sub.1 is greater than the electron beam cross-sections, said foil means producing bremsstrahlung radiation when the surface is struck by electrons from an electron beam;
• b. means for moving the foil means transversely through the electron beam paths with the surfaces facing the electron beams;
• c. first radiation detector means located circumferential about the beam path at a distance displaced from the foil means in the direction of travel of the first beam for detecting radiation from the foil means produced by the first electron beam;
• and
• d. second radiation detector means located circumferential about the beam path at a distance displaced from the foil means in the direction of travel of the second electron beam for detecting radiation from the foil means produced by the second electron beam;
• and
• d. means for measuring the intensity of the radiation detected by the first and second detector means as a function of the position of the foil means in the beam paths.