Design and development of a prototype of superconducting compact cyclotron

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The present work has been performed in 1991 and 1992. A prototype of superconducting cyclotron had been kept in custody at the chemical research institute, Kyoto University. The cyclotron has a pole of 15.5 c m in radius for 10 MeV protons and the yoke of about 4 ton. In 1991 we have carried out a transportation and an installation of the prototype, and established a research structure a Kyushu University. Calculations have been carried out t o design the optimum magnetic field and to examine the beam properties in equilibrium and accelerated orbits. The field shape has been determined through least-square analyses for an optimum condition for isocronous and focusing. These results were published in a symposium in 1991. A magnetic-field measurement system has also been constructed with flip-coils in order to test the cyclotron magnet. In 1992 we have performed a design calculation of the central region to obtain an optimum condition for beam injection from the ion source. In the present work we are aiming at the construction of prototype with no trimming coils under a high magnetic field of about 3.2 T. This should require a high accuracy i n the design calculations, so a program-code has been developed for 3-dimensional simulations. As an optimum condition for beam accelerations have been determined the shape of electrodes, and the voltage and the initial phase for beam injection. In order to test the cyclotron magnet we estimated the heat flow into the liquid-helium reservoir in cryostat by radiation and conduction, and found the consumption of liquid-helium can be minimized to about 3.6 l/hour by using the optimized power-leads. From the work in this project we have found the feasibility for further investigations.