On the emission of X-rays in a FXR discharge

Pinhole camera exposures of a flash X-ray (FXR) discharge show that X-radiation is emitted from (i) the plane parallel electrode surfaces, (ii) a cloud outside the anode centre, and (iii) the cylindrical anode surface. It is found that the cathode X-radiation is secondary and that secondary X-radiation is also emitted by the wall of the discharge tube. The X-radiation from the cylindrical anode surface is found to be due to the bombardment of photoelectrons emanating from the tube wall.