The MARS-D project will produce a 4th Generation Electron Cyclotron Resonance Ion Source (ECRIS). MARS-D is expected to outperform the 88-Inch Cyclotron’s world leading 3rd Generation VENUS ECRIS. The transition from a 3rd Generation to a 4th Generation ECRIS means that both higher intensity beams and higher charge state beams can be provided to the 88-Inch Cyclotron for experiments, and this is made possible with stronger plasma confining magnetic fields. In an ECRIS, the plasma confining fields are typically provided by a conventional configuration that uses a combination of solenoids and a set of six racetrack coils. Using this conventional configuration, the upper limits of the superconducting NbTi wire, for use in an ECRIS, have been reached. MARS-D will be able to achieve stronger fields than VENUS, while also using NbTi superconductor wire, because of its novel magnet configuration that will replace the six racetrack coils which provide the radial confining field. The novel magnet configuration is a closed-loop coil that will provide both a radial confining field as well as solenoidal fields that will add to the axial confinement of the plasma .
The 88-Inch ECRIS Group and the SMP group received funding through a DOE Office of Science Funding Opportunity Announcement (FOA) in 2023. The two year project will produce the coldmass (sextupole and solenoid magnets) for the MARS-D ECRIS, to be built at a later date. Recently, the group successfully completed a full size 4 layer test wind using NbTi, shown in Figure 1. The winding of the final coil will begin in January of 2024 and consist of 24 layers. The test wind allowed the group to perfect the winding tooling, test the epoxy impregnation, and observe effects of cooling down on the coil.
Figure 1: The completed NbTi 4 layer test coil is shown after epoxy impregnation is completed.
The success of the test wind is owed to the hard work of the technicians at the 88-Inch Cyclotron and ATAP: Brian Bell, Patrick Coleman, John Garcia, Roman Nieto, Matthew Reynolds, Nathan Seidman, Chet Spencer, James Swanson, Sixuan Zhong, the lead designer Lianrong Xu, and the 88-Inch Mechanical Engineer Jaime Cruz-Duran.
References:  M. Juchno et al., Shell-based support structure for the 45 GHz ECR Ion Source MARS-D,” IEEE Trans. Appl. Supercond., vol. 32, no. 6, Sept. 2022.