Physics, Techniques and ProceduresGenerator of high voltage
a device which by means of a
transformer assembly produces alternating high voltage. (See
X ray generator for the explanation and principles of modern
X-ray generators.) Unidirectional
X ray tube current is obtained by means of a
rectifier, allowing current to flow in one direction only. The following list covers generator types used in diagnostic radiology even today, but many possess historical interest only:
1. Cascade generator circuit, see (9) Marx circuit.
2. Cockcroft - Walton circuit. A circuit in which an assembly of transformers, condensers and valves serves to charge a further condenser to twice the voltage of the transformer. The output voltage is substantially constant and may be increased to any practicable multiple of the transformer voltage by the addition of further components in cascade.
3. Constant potential circuit. Any circuit in which for instance an arrangement of condensers is used to maintain a voltage which is substantially constant.
4. Full-wave circuit. A circuit in which the negative half-cycle is reversed before it is applied, thus utilizing both half-cycles effectively.
5. Half-wave circuit. A circuit arranged so that current can flow during positive half-cycles only.
6. Impulse generator circuit, see (9) Marx circuit
7. Latour circuit, see (8) Liebenow - Greinacher circuit.
8. LiebenowGreinacher circuit. A constant potential voltage-doubling circuit in which two condensers connected in series are each charged in alternating half-cycles, thus giving a substantially constant potential which approaches twice the transformer voltage.
9. Marx circuit. A circuit so arranged that condensers can be charged in parallel and discharged in series. The switching can be either mechanical or by spark gaps, and the process may involve one impulse or a succession of impulses.
10. Rectified three-phase circuit, see (11) six valve circuit.
11. Six-valve circuit. A circuit in which the negative half-cycles of the three components of a three-phase supply are reversed before being applied, producing an unidirectional pulsating voltage with a ripple of about 14 % (see ripple factor).
12. Willard circuit. A voltage-doubling circuit in which a condenser is charged, its voltage being added to that of the transformer thus producing a unidirectional voltage which may approach twice the peak voltage of the transformer.
13. Witka circuit. A voltage-trebling circuit in which two condensers are charged, their voltages being added to that of the transformer, thus producing an unidirectional voltage which varies from the peak voltage of the transformer to a value approaching three times that voltage.
See also battery powered generator, capacitor discharge generator, constant potential X ray generator, falling load generator, single phase X ray generator, three phase X ray generator.
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