Shizhong An

Experimental study for 15–20 mA dc H- multicusp source

Recently, a new H- source and test stand was developed at CIAE. The design of this new source is based on the experience on our previous 10-15 mA H(-) ion source and the source at TRIUMF. Major efforts include the study of the virtual filter magnetic field, confining magnetic field, filament shape and location, the vacuum improvement on the extracting area, the extraction optics, new control and interlock system of the power supplies. More than 15 mA of H-beam was obtained for 36 h with stability of +/-0.5%. The normalized emittance of 0.48pi mm mrad (4 rms normalized emittance) were measured with approximately 8 mA dc beam. Further experimental studies are proceeding in an effort to reach 20 mA with reasonable emittance at this moment. More study plans are conducted, e.g., building a longer source body and using cesium injection to get better emittance, which will be presented as a separate paper at this conference.

Magnet Design of an 800 MeV High Power Proton Cyclotron

The high-power proton beam has wide applications in neutron and neutrino physics, radioactive ion-beam production, ADS systems, proton radiography, and nuclear data measurement, etc. Cyclotrons are intrinsic in continuous-wave beam mode, which has the characteristics of high efficient power conversion rate, compact structure, and relatively low construction cost. A high-power 800-MeV proton cyclotron was proposed by CIAE, and the prestudy on the cyclotron was carried out since the year of 2009. The main magnet is among the most crucial and challenging subsystems. In contrast to low beam current cyclotron, the main magnet system of high beam current cyclotron needs to provide very strong vertical focusing force to avoid the beam blowup caused by dangerous resonances and space charge effects. In this paper, the 3-D modeling and optimizing work on this large-scale magnet system are presented in detail.

The Assembly and Adjustment of the Second Stripping Probe System for CYCIAE-100

The project of Beijing Radioactivity Ion-beam Facility (BRIF) is being constructed at CIAE. As a major part of the BRIF project, the 100 MeV compact cyclotron (CYCIAE-100) will provide proton beam with an intensity of 200-500 μA. The extracted proton energy range is 75-100 MeV with the carbon foil stripping system. The stripping probe system is the major part of the extraction system for CYCIAE-100,

Design, Construction, Installation, Mapping, and Shimming for a 416-ton Compact Cyclotron Magnet

The construction of a 100-MeV high-intensity cyclotron, from which proton beam will be extracted through stripping to several proton beam lines for different users, has been completed at China Institute of Atomic Energy. Given that it is the H-ions that are to be accelerated in the machine, the peak field is only 1.35 T. To simplify the fabrication, the pole adopts straight sector instead of the spiral one. Meanwhile, vertical focusing should be sufficiently high to obtain high-current proton beam. All these demands make it particularly difficult for the design and fabrication of the main magnet, which is heavy in weight and challenging to meet precision requirement in fabrication. In the process, we have developed a high-performance parallel computation PIC code for beam dynamics of high-current cyclotrons and for FFAGs, which can be used for beam dynamic simulation at a very precise level. The result is then applied to guide the design, fabrication, installation, magnetic mapping, and shimming of the 416-ton main magnet with a precision requirement up to 0.05 mm. Another challenge is due to the deformations of the magnet without/with the vacuum. The whole map measured in the vacuum has to be completed in such a big machine for the first time in the world. The result shows that all requirements, including the isochronous field, vertical focusing, and imperfection fields, have been satisfied properly. The first beam and the stable beam for an 8-h commissioning test had been achieved on July 4 and July 25, 2014, respectively.

Magnet Design for a 70 MeV

A 70 MeV cyclotron for radioactive ion beam production and other applications has been designed at China Institute of Atomic Energy (CIAE). The main challenge of the magnet design for this particle machine lies in the needs of two isochronous magnetic fields to accelerate H- and D- with charge-mass ratios of 1 and 0.5 respectively. The required isochronisms are achieved by installing removable shims and adjusting the RF frequency. The magnetic fields and beam dynamics design results for both H- and D- beams are described in this paper. The analysis on field imperfections caused by the magnet deformation and the effects of annealing on magnetic properties of materials, are also outlined.