| Abstrakt: |
Modern methods of generating the high voltage required for the excitation of X-ray tubes are discussed from the electrical aspects of efficiency, effect on the apparatus, and possibility of direct measurement.The direct current supply from transformers and valve rectifiers with condensers is shown to be the best from the above electrical aspects, and it is suggested that standardisation on this or some similar circuit could well be discussed, to the ultimate advantage of the manufacturer and the user.The Greinacher circuit using two valves and two condensers is dealt with in some detail, and test results on an experimental low-voltage circuit of this type are given and discussed. From these results are deduced some points in design and an outline specification for a continuous voltage plant for 100 milliamperes and up to 80–90 kilovolts. These results are also analysed and found to conform to calculations.Other desirable features in design, include voltage selection in only three or four steps, control by tappings on the primary of the transformers, X-ray tube current setting by filament rheostat, and exposure controlled by a wattsecond relay so as to minimise the effect of line voltage fluctuations. |
