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Description
The 3rd-generation ECR Ion Sources, constructed with Nb-Ti superconducting wires and the conventional racetrack-and-solenoid structure, have been successfully operated for over two decades, achieving operating frequencies up to 28 GHz and utilizing about 90% of the critical current of the Nb-Ti wire. A Mixed Axial and Radial field System (MARS) ECRIS is being developed at LBNL. This system, which consists of an innovative hexagonal Closed-Loop Coil (CLC) and a set of solenoids, can generate magnetic fields up to 50% higher, enabling Nb-Ti wires to be used in the 4th-generation 45 GHz ECRIS. However, the fabrication of the CLC is the most challenging due to the complicated winding route and shape, the hard rectangular Nb-Ti superconducting wire, the small bending radius, and so on. A pre-over-bending approach and a set of unique fixtures and tools were developed to ensure successful coil winding. Also, the assembly and cooling of such efficient and compact magnets are particularly challenging due to the small radial gap between CLC and solenoids, as well as the tight operating temperature margin. To address these challenges, a structure was developed that combines a three-section radially split solenoid mandrel with a series of interference-fit reinforcement rings. This paper presents the MARS structure; the CLC winding fixtures, tools, and procedures; the solenoid mandrel and coil winding; the magnet impregnation; the cold mass assembly; and the cryostat design.
Funding Agency
This work was supported by the U.S. Department of Energy, Office of Science, Office of Nuclear Physics under contract number DE-FOA-0002670.
| Classification | MC2: New concepts and next generation sources |
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