Electrical insulators for various types of superconducting magnets are reviewed. Epoxy resins and their composites have been widely used for magnets of radiation resistance up to 1×10
7Gy (1×10
9rad). For higher radiation resistant magnets (-1×10
8Gy) polyimides and their composites should be adopted. Adequate study should be made to select insulators for INTOR magnets which are expected to with-stand 2-5×10
7Gy.
For resin moulded type magnets, epoxy resin impregnants with adequate toughness at cryogenic temperatures should be adopted with vacuum pressure moulding process. Turn layer insulators, ground wall insulators, and spacers between pies are needed for pool boiling type magnets. These insulators are all FRP in their last state. High density FRP with low thermal contraction and high compressive strength have been developed in several countries. They are compared in their properties essential for spacer use.
Ground insulators for forced flow type magnets are also reviewed. Voltage withstand test conditions for superconducting magnets are checked. FRP cryostats or dewers have been constructed in several facilities. Some unique cryostats, W type and U type, are introduced.
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