Abstract
A helical-type fusion reactor uses huge-scale dc superconducting magnets driven up to 100-kA dc to make a steady-state magnetic field to confine the fusion plasma. The required voltage to keep the current in the steady-state operation is close to zero; thus, a dc power supply is required, whose output rating is 100 kA and 0.1 V. To realize such low-voltage power supply, a converter that works under low frequency such as 0.1 Hz is applicable due to the large load inductance. Having such a low-frequency-and-voltage operation, mechanical contacts driven by piezo devices can be beneficially used as switching devices in the converter. With this switching device, the forward voltage drop becomes lower than the semiconductor devices, and the power loss in the steady state can be reduced. A conceptual design of this converter has been made confirming the operation of a piezo-driven mechanical switch device in dc power supply.
Highlights
A helical type fusion reactor uses huge scale dc superconducting magnets driven up to 100 kA DC to make a steady state magnetic field to confine the fusion plasma
N the National Institute for Fusion Science (NIFS) in Japan, projects related to fusion energy are ongoing
A superconducting magnet of FFHR stores over 170 GJ of magnetic energy and its operating current will be 100 kA. These superconducting coils making up the magnet are operated in dc condition, and the required voltage to keep the current in the steady state is very low their large current
Summary
Reactor (FFHR)”[1][2] Such of a large fusion plant uses a large dc superconducting magnet to generate the magnetic field confining the fusion plasma. A superconducting magnet of FFHR stores over 170 GJ of magnetic energy and its operating current will be 100 kA. These superconducting coils making up the magnet are operated in dc condition, and the required voltage to keep the current in the steady state is very low their large current. To resolve the above situation, we have started to design an extra low voltage dc power supply that operates in cryogenic condition Using such large scale coils, their inductance will be large and the required voltage low. Mechanical contact is a key device, a small model is made and tested
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