Metallic bellows are today used for a variety of application in wide range of fields from fusion reactors to simple vacuum components. These are mainly two types (1) welded bellows and (2) formed bellows, each of which are designed with different characteristics for different application. In this report the design of such bellows is described. In particular a new method of life-time calculation given by combination of examination and theoretical consideration will be explained. The usefulness of such calculations in terms of suitable bellows design and product standardization will also be outlined. New materials for the production increased life-time bellows will be looked at and finally we will show the application of metallic bellows in such areas as paticle-free gate valves for semiconductor production/processing equipment which require life-time >106 cycles, fusion reactors, particle accelerators and power electronic devices.
High stress arising from thermal and electromagnetic force is generated during energizing the superconducting magnet. The effect of this stress must be noted especially for large magnet. In addition to this, stress distribution has been found to be irregular and complicated, thus it is important to evaluate the rigidity of superconducting magnet. Each spacer between the conductor bears higher compressive force than the conductor, which have great concern with the rigidity of the magnet. In this report we evaluate the behavior of the magnet in totality by means of homogeneous doughnut disk model and equivalent elastic module's. In the meanwhile there is one other thing that is important for superconducting magnet. One of the most effective factors to deteriorate the stability of the magnet is mechanical disturbance, for example, the behavior of the friction. In this report we are concerned with the movement of the conductor arising from electromagnetic force. We calculated the force of the conductor and between the conductor and spacer. It was found that heating which is cause of Quench occurs most easily in inner layer, which is nearest axis, of the magnet. The possibility of heating was found to depend on the location of conductor and spacer. Hence it is important to evaluate the location of spacer.