Conceptual Design of an Octupole Magnet for PEFP Beam lines

The Proton Engineering Frontier Project(PEFP) will supply the 20MeV and 100MeV proton beams to the users. 10 beam lines have been designed and will be installed not only for the demonstration test of beam utilization technologies but also for the industrial applications until 2012. For the various field applications, the proton beam with wide uniform distribution has been required. There are several methods to irradiate the large area at the target. For the raster scan and the wobbling, the uniform irradiation is accomplished by sweeping small beams with a pair of dipole magnets. But these scanning methods have some disadvantages to apply the pulsed beam. And there are several passive methods which using thick absorbers, occulting rings and scatterers. These methods also have problems. So we studied, the non-linear optical method, the octupole magnet which can bend the tails of Gaussian beam back toward the center by the strong fields away from the center. In this study, design requirements and designed parameters of the octupole magnet for PEFP beamlines are described