Electron beam current stabilizing device

An electron beam current stabilizing device for use with an accelerating tube having a heater cathode connected to a heater transformer supplied from one of the secondary windings of a high-voltage transformer of an acceleration voltage source, said device comprising a photosensitive element connected to the cathode of the accelerating tube to adjust the beam current, and a light source to control the photosensitive element, characterized in that it further comprises a sensing element (12) responsive to the beam current deviation from the predetermined value, a saw-tooth voltage shaper (14) connected to the high-voltage transformer (2) and providing periodic saw-tooth voltage, smoothly sloping portions thereof being shaped starting from the moment when the voltage at the high-voltage transformer (2) crosses zero an adder (13) whose one input is connected to the output of the sensing element (12) and whose other input is connected to the output of the saw-tooth voltage shaper (14), a threshold element (15) connected to the output of the adder (13), and a differentiator (16) connected to the output of the threshold element (15) to shape the electric driving pulses when the smoothly sloping portions of the saw-tooth voltage cross the threshold level of the threshold element (15) at the output of the adder (13), the light source being connected to the output of the differentiator (16) to convert the electric driving pulses into the light pulses while, the photosensitive element is made as a photothyristor (II) inserted in the primary winding circuit of the heater transformer (5).