| 摘要 |
PURPOSE:To improve reliability by using a switch having small capacity and operating at high speed as a switch for a circuit for current rise and employing a mechanical type switch having large capacity and operating at low speed and a diode as a switch for a circuit for sustaining currents. CONSTITUTION:A power unit supplying a field coil for a nuclear fusion device with currents is provided with a high-voltage power supply 2 for current rise and a low-voltage power supply 1 for sustaining currents, and makes large currents flow through a load coil 6 through switches 33, 34 and a diode 5 from both power supplies 2, 1. A switch (a mechanical switch such as a VCV), which operates at low speed but has large capacity, is used as the switch 34, and a switch, which takes a nonmechanical type such as an ignitron, a thyristor, etc. and operates at high speed but has small capacity, is employed as the switch 33. Accordingly, conduction is started to the load coil 6 from the high- voltage power supply 2 on ON of the switch 33 and currents are made to rise, and the switch 34 is also turned ON at a time when high-voltage power supply and low-voltage power supply are brought to the same potential, thus sustaining conduction.
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