The development of radial probe for cyciae-100

In the design of CYCIAE-100 beam diagnostics system, three radial probe targets distribute on three directions above magnetic pole and in the valley on the median plane of cyclotron. These radial probe targets can be used for beam center measurement. By blocking beam on five fingers and one stopping block, the radial probe target can measure the radial and axial distribution of H beam at the same time. During beam commissioning, the radial probe targets can also be used for beam intensity measurement. The changeable target tip design makes it possible to replace the damaged part and optimization of the structure. The mechanical and control part of radial probe target system is finished, assembly and prime test of the whole system will be carried out in September. DESIGN OF RADIAL PPROBE The project of Beijing Radioactivity Ion-beam Facility (BRIF) is being constructed at China Institute of Atomic Energy (CIAE). As a major part of the BRIF project, a 100MeV compact cyclotron (CYCIAE-100) will provide proton beam with an intensity of 200μA 500μA [1]. CYCIAE-100 is a compact isochronous cyclotron. The radius of magnetic pole is 2000 mm, yoke is 3080 mm, air gap between 46-60 mm. Large radius with small axial space plus high requirement of isochronous magnetic field, all these factors lead to the following design of radial probe target: 4580 mm long, placed on the median plane of CYCIAE-100 cyclotron, above the surface of magnetic pole, bellows with compression ratio as high as 0.234 is chosen for vacuum seal. The moving range of radial probe target is 2020 mm to assure the radial probe measurement range near the centre of CYCIAE-100 [2]. When not measuring, radial probe target is blocked off from main vacuum chamber by a gate valve. The position of three radial probe targets on CYCIAE-100 is shown in Fig. 1. Figure 1: Radial probe targets on CYCIAE-100. For the purpose of beam center measurement, three radial probe targets will be installed on three directions above magnetic pole and in the valley on the median plane of CYCIAE-100 cyclotron. Meanwhile, at low energy, radial probe target with water cooling can get real time beam intensity which is important parameter for prime beam commissioning. The main functions of radial probe target are as follows: Get Beam Distribution on Axial and Radial Directions at the Same Time The radial probe target tip, making up by five fingers and one stopping block in front, get the beam distribution on axial and radial directions by blocking the beam. Radial probe target tip is made by copper. The five fingers’ positions are decided according to the calculated axial beam distribution. The five cuboid fingers with 0.5mm cuneate tip outside the stopping block can satisfy the radial resolution requirement. The five fingers are symmetrical to the median plane of CYCIAE-100, as shown in Table 1. Table 1: The Size of Five Fingers Finger No. Position Size