Mamoru Katane

An untuned RF cavity using multifeed coupling

Abstract A ferrite-loaded untuned RF cavity was designed and fabricated as the accelerating structure for a compact proton synchrotron dedicated to cancer therapy. An invented power-feeding method, “multifeed coupling”, was used to achieve a gap voltage higher than 700 V with an applied RF power of 1.2 kW in the frequency range 1.5–8 MHz and a cavity length 0.4 m. The temperature in the ferrite cores had less than a 22°C rise from room temperature using only forced air cooling.

A compact proton synchrotron with combined-function lattice dedicated for cancer therapy

A compact proton synchrotron with combined function lattice has been designed as a dedicated machine for cancer therapy because of its merits of easy operation and low construction cost. The lattice has a six-fold symmetry and its radius of curvature and circumference are 1.9 m and 23.9 m, respectively. For the purpose of establishing a good reference design, we have constructed a model magnet based on the three-dimensional magnetic field calculation. A magnetic field measurement has been performed with use of a three-dimensional Hall-probe. In the present paper, the results of these developments is presented together with the outline of the reference design.

Fabrication of a copper chamber for a storage ring with broached inner surface

Abstract There have been several reports that photodesorption due to synchroton radiation from OFC copper chambers with machined surfaces is far lower than in stainless steel or aluminum alloy chambers. However, it is difficult to process machined surfaces for the inner surfaces of beam chambers. A surface treatment using broaching has been developed to cut the inner surface of the chamber. Tests of the photodesorption caused by synchrotron radiation in a small, broached, cylindrical cross-section chamber with a length of 30 cm have been reported. To adapt the broaching method to long chambers, prototype copper vacuum chambers with lengths of 1.8 m and 2 m have been fabricated. A chamber consists of a beam channel, a cooling channel, and a NEG pump channel. The beam channel, which has a hexagonal cross section, is broached. An ultimate pressure of 1 × 10 −8 Pa was obtained after bakeout at 200 °C for 24 h and NEG activation.