ABSTRACT
The rotating anode, which is facing downward about an inch above the cathode at the bottom, has a diameter of 90 mm and was spun for this photo at 49 rotations per second. At the left on the conical surface of the anode, a restricted white glowing rectangular zone of about a millimeter width and about 10 mm radial length is visible. The origin of X-rays is the focal spot at the periphery of the truncated cone of the anode disc, which is the key component of the rotating anode. Upon impact of electrons from the cathode, photons fan out from this center of interaction of electrons in all directions. The kinetic energy of the electrons, which impinge on the target, is basically defined by the difference between the electric potentials of the target surface of the anode where the electrons impinge and the filament of the cathode where they start from, multiplied with the electron charge.
