On a New Type of X ~ Ray Generator

The principle of the described X-ray generator is a variation upon the direct-current inductor, the grid-controlled X-ray tube itself acting as the interrupter. The anode of the X-ray tube is connected to a constant-voltage generator via a high-inductance coil. The capacitance is constituted by the sum of the capacitances of the tube, the leads and the coil. The main feature of the X-ray tube is the electron gun, consisting of a multi-grid construction of the Pierce type and a dispenser cathode with a concave emitting surface. The tube current is controlled by variation of the accelerating-grid voltage. By applying periodically a negative voltage pulse of rectangular wave form to the accelerating grid the capacitance is loaded at a low voltage and discharged at a high voltage alternately. The main data are: maximum voltage 250 kV, maximum tube current 300 rnA, repetition frequency about 1100 c/s, discharge time about 50 f.tS. Also a spectrometer is described specially designed for measuring the high voltage and the spectral-energy distribution of the X-radiation produced.