Gaofeng Pan

H− cusp source development for 100 MeV compact cyclotron at China Institute of Atomic Energy

As a part of the Upgrade Project of Beijing Tandem Accelerator Laboratory, a 100 MeV compact cyclotron was designed for the generation of high intensity proton beams. Due to the limit of acceptance by the cyclotron central region, a new H− cusp source was developed at China Institute of Atomic Energy. The design of this new source is based on TRIUMF’s experience. More than 10 mA of H− beam with a measured emittance of 0.65 π mm mrad are obtained at a voltage of 28 kV from an extraction hole of 11 mm in diameter. In this article, the structure of the source, the magnetic field configuration of the multicusp and virtual filter, the extraction optics, the test results, and future improvements will be described.

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 and Fabrication of CYCIAE-14, a 14 MeV PET Cyclotron

In line with the increasing demand for PET cyclotrons in China, the construction of a 14 MeV high intensity compact cyclotron, CYCIAE-14, has been proposed at China Institute of Atomic Energy (CIAE) in 2010 and is scheduled to be finished within two years. The fabrication is in smooth progress, with a majority of the devices ready in place for installation. As a critical part of the cyclotron, the main magnet development is of paramount importance to the successful development of the machine. At present, the main magnet design and fabrication has been accomplished. The physics design of the main magnet, which enables the realization of strong focusing by adopting a 4-sector structure with variable hill gap, will be emphatically introduced in the paper. Meanwhile, the engineering techniques applied to the fabrication will also be presented, in particular the technical challenges encountered in the process. Based on the accomplishment of two sets of main magnets, six more sets of main magnets will be fabricated.

Ion source and low energy injection line for a central region model cyclotron

At CIAE, a 100 MeV H(-) cyclotron (CYCIAE-100) is under design and construction. A central region model (CRM) cyclotron was built for various experimental verifications for the CYCIAE-100 project and for research and development of high current injection to accelerate milliampere H(-) beam. The H(-) multicusp source built in 2003 has been improved recently to make the source operation more stable. A new injection line for axial low energy high current injection has been designed and constructed for the CRM cyclotron.

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.

Some R&D for the update project of Beijing Tandem Laboratory

A update project of the Beijing Tandem Laboratory was proposed in 1999. The main part of this project is the construction of a 100 MeV high intensity H/sup c/yclotron. Some R&D for such a cyclotron have been ongoing for two years, e.g. the axial injection line which is able to inject a 5.2 mA DC beam to the central region of the machine recently. In this paper, the progress of R&D for the ISOLs target-source system will also be reported.