Repetitive Pulsed X-Ray Generator Utilizing A Triode

Abstract

ABSTRACT A repetitive pulsed x-ray generator utilizing a triode for biomedical radiography is described. This generator consisted of the following components: a high-voltage power supply, a cable condenser with a length of 10m and a capacity of about lOOOpF, a repetitive impulse switching system, a turbo molecular pump, and a pulsed x-ray tube having a cold cathode. The x ray tube was of the triode type which was connected to the turbo molecular pump and consisted of the following components: a rod-shaped anode tip made of tungsten, a ring cathode made of molybdenum, a ring trigger electrode made of iron and other parts. The trigger electrode was attached to the cathode electrode just inside of the x-ray window and the space between the cathode and trigger electrodes was less than 0.5mm. The anode-cathode (A-C) space was adjusted outside of the x-ray window for controlling the A-C impedance. The cable condenser was charged from 30 to lOOkV by the constant voltage generator and was discharged repetitively by the impulse switching system utilizing a frequency control system with a high time resolution. The maximum frequencies varied according to the charging voltage, the condenser capacity which was determined by the length of the cable condenser, and the current capacity of the high voltage power supply. The frequencies of this generator were less than lOOHz, and the pulse widths of the pulsed x-rays were less than 300ns. The time integrated x-ray intensity was less than 5.0jjC/kg at 0.5m per pulse, and the effective focal spot size ranged from 0.5 to 3.0mm.