Joshua Kellams

Accelerator-driven subcritical fission in molten salt core: Closing the nuclear fuel cycle for green nuclear energy

A technology for accelerator-driven subcritical fission in a molten salt core (ADSMS) is being developed as a basis for the destruction of the transuranics in used nuclear fuel. The molten salt fuel is a eutectic mixture of NaCl and the chlorides of the transuranics and fission products. The core is driven by proton beams from a strong-focusing cyclotron stack. This approach uniquely provides an intrinsically safe means to drive a core fueled only with transuranics, thereby eliminating competing breeding terms.

New Magnet Technology for a 1.5 T Open-MRI Breast Imager

Structured windings and steel poles can be used to create a homogeneous field in a volume of interest (VOI) outside of a coil configuration. The methodology is explained and a first application to an optimized open-MRI imager for breast imaging is presented. Similar methods have been used to design a gradient coil set to similarly project uniform gradient into the same VOI. Aspects of the design and cryogenics of the magnet are discussed.

Strong Focusing Cyclotron and Its Applications

A Strong Focusing cyclotron has been developed by the Accelerator Research Lab at Texas A&M to produce up to 10 mA of proton beam at 800 MeV. The cyclotron has several innovations that allow it to achieve such high levels of power. The first is the superconducting RF cavities that provide sufficient gain to separate the orbits by a minimum of 6 cm. This space allows for beam transport channels to be place along every orbit and provide continuous quadrupole focusing. Additionally, a trim dipole is added to the channel to allow for corrections to the main dipole. This document will show the new BTC design that allows for the cyclotron to be greatly simplified. The main dipole is kept below saturation and is shaped to levitate the poles. The main dipole, along with the RF cavity, are designed such that several cyclotrons could be stacked on top of one another. This design provides the high power beam required for several applications. These applications include accelerator driven systems, neutron damage facilities, and medical isotope production. Texas A&M has developed two designs for ADS fission: an isoburner and an isobreeder. Both of these designs will be expounded on within the document. A design for a neutron damage facility and it capabilities are presented as well as a medical isotope production design. The SFC has great potential to revolutionize these fields and be of great service to the US.

Cable-in-Conduit Dipoles to Enable a Future Hadron Collider

We report the development of a new approach to dipole technology, based upon cable-in-conduit conductor, that optimizes the cost and performance for a future ultimate-energy hadron collider. Optimization of cost for an ultimate-energy hadron collider is dominated by the strong dependence of magnet cost and synchrotron radiation power upon the dipole field strength. Assuming that the collider is built at a site with minimum tunnel cost, the projected total project cost is minimum for a ∼4 T dipole field. We present a novel option in which the double-ring of magnets is housed in a circular pipeline, submerged with neutral buoyancy at a depth ∼100 m in the sea. Such a collider inscribed in the Gulf of Mexico would provide hadron collisions at 500-TeV energy with a luminosity of 5 × 1035 cm−2s−1. We describe here the design of the dipole and of the pipeline cryostat that would contain it.

Nanoparticle Ag-enhanced textured-powder Bi-2212/Ag wire technology

A new approach to the preparation of cores for Bi-2212/Ag wire is being developed. Nanoparticle Ag is homogeneously dispersed in Bi-2212 fine powder, and the mixture is uniaxially compressed to form highly textured, cold-sintered core rods. The rods can be assembled in a silver matrix, drawn to form multifilament wire, and restacked and drawn to form multifilament wire. Preliminary studies using tablet geometry demonstrate that a nonmelt heat treatment produces densification, grain growth, intergrowth among grains, and macroscopic current transport. The status of the development is reported.

Superconducting Sector Dipole for a Strong Focusing Cyclotron

A superconducting strong focusing cyclotron (SFC) is being developed for high current applications. The dipole magnetic field required for isochronous operation is provided by sector magnets utilizing a common warm-iron flux return and levitated cold-iron pole design. The sector magnets utilize MgB2 superconducting cable operating at 15-20 K. The sector dipoles for a 100 MeV SFC were modeled to provide for isochronous operation. The field distribution, fringe fields, forces and torques in the dipole were calculated.

Design of a

A superconducting strong-focusing cyclotron is being developed for high current applications. Alternating-gradient focusing is provided by ~ 6 T/m superconducting beam transport channels which lie in the sectors along the arced beam trajectory of each orbit of the cyclotron. The ~ 1 T sector dipoles, corrector dipoles, and Panofsky type quadrupoles utilize MgB2 superconductor operating around 15-20 K. The operating temperature provides a valuable margin for a cost-effective cryogenic design, and large thermal stability in the event of occasional heat loads from intercepted beam or other sources. The main dipole windings are designed with sufficiently large curvature so that they can be fabricated using react-and-wind procedure; the quadrupole windings require small-radius end bends and so must be fabricated using wind-and-react procedure. Initial magnetic modeling on the end field region is presented.