NEW LOW IMPEDANCE HIGH INTENSITY X-RAY GENERATOR USING FIELD EMISSION FOR BIOMEDICAL DIAGNOSIS

Abstract
A new low impedance high intensity single x-ray generator using field emission and its applications to biomedical diagnosis are described. This generator consisted of the following essential components: a high voltage generator, a low impedance transmission line using an oil condenser of 120kV-0.15µF, a high speed impulse switching system with a time resolution of less than lus, and a new type of x-ray tube having two sets of electrodes using field emission. This tube was supported by a large scale electric tube holder, and it was possible to rotate, raise, and lower it corresponding to the radiographic objectives. The generator could be used for condenser charging voltages of 50 to 120kV and peak currents of 20 to 40kA. The maximum intensities for the Type A and B electrodes were about 20 and 40C/kg at 1m/pulse, respectively. The exposure time was about 1µs. The optimum output corresponding to the optimum x-ray quality could be controlled. The size of the effective focal spot primarily varied according to the electrode configurations and the insertion of metal filters, and ranged from 0.2 to 3.0mm in diameter. Various kinds of high speed radiography, (e. g., continuous delayed radiography) were accomplished by controlling the source conditions concerning the x-ray intensity, the quality, the effective focal spot, and the delay time.