Electrical insulators radiation damage

Polyimides are good insulators and particularly resistant to electrical and radiation damage. They are used as structural adhesives, for electric motor insulation, for high performance cable and wire coatings, and for printed circuit boards. 

The greater tolerance for radiation damage in inorganic materials makes them attractive for fusion magnets, but their brittleness and the difficulty of fabrication techniques presents a serious limitation to their practical uses. Therefore, the application of organic materials has been considered for electrical insulators, thermal insulators and a part of structural supports in the magnets [4 9]. 

III. In some instances, recent data on relevant properties at low temperatures are available, as in the NBS-ARPA-Battelle Handbook [% but more are needed. In particular, data on low-temperature properties of materials for very large loadcarrying welded or bolted structures are not available. Radiation damage at 4 K and the effect of thermal cycling on irradiated metals and organics are other areas where little information is available. The same is true of composite materials, both as structural elements and as thermal and electrical insulators. Furthermore, since very large quantities of material will be necessary, and the structures will probably be subject to close public scrutiny, attention must be paid to heat and product-form... 

Actuators. The problem of radiation damage to hydraulic fluids, elastomers, or electrical insulations is avoided by utilizing pneumatically powered metallic bellotvs for remote actuation of the valves. The actuator is a simple linear device which can be controlled with standard pneumatic controllers or regulators. The bellows may also be stacked to multiply the forces available. In the HRE 2, pneumatic actuators develop up to 5440 lb force. 

For some applications, photoreceptors are prepared with surface layers for protection from chemical, radiation, and physical damage. Most surface layers are less than 5 pm. A key electrical requirement is the conductivity. If the layer is too insulating, a residual potential will build up during cycling. Thus, this... 

Part 5 of the lET Regulations tells us that electrical equipment and materials must be chosen so that they are suitable for the installed conditions, taking into account temperature, the presence of water, comosion, mechanical damage, vibration or exposure to solar radiation. Therefore, PVC insulated and sheathed cables are suitable for domestic installations but, for a cable requiring mechanical protection and suitable for burying underground, a PVC/ SWA cable would be preferable. These two types of cable are shown in Figs 3.38 and 3.39. 

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