These SBIR/STTR data are furnished with SBIR/STTR rights under Grant No. DESC0009526. For a period of four (4) years after acceptance of all items to be delivered, under this grant, the Government agrees to use these data, for Government purposes only, and they shall not be disclosed outside the Government (including disclosure for procurement purposes) during such period without the permission of the grantee, except that, subject to the foregoing use and disclosure prohibitions, such data may be disclosed for use by support contractors. After the aforesaid four-year period, the Government has a royalty-free license to use, and to authorize others to use on its behalf, these data for Government purposes, but is relieved of all disclosure prohibitions and assumes no liability for unauthorized use of these data by third parties. This Notice shall be affixed to any reproductions of these data in whole or in part.
1. Summary of accomplishments of Phase I
Phase I of this SBIR explored novel ideas to reduce the cost of conductor, shielding and refrigeration for ring magnets for a muon collider of 1.5 TeV center-of-mass energy. A ring 2.5-km in circumference might require ~$500 M of superconductor (if Nb3Sn), ~$100 M of tungsten to shield the magnets from the radiation originating with muon decay, and ~$5 M/yr of electrical power for 4-K refrigeration of the cold mass (magnets plus cold support structure) even with shielding thick enough to intercept all but ~1% of the ~2.4 MW of heat released by the decaying muons. The Phase I study optimized magnet systems consisting of a compact combined-function magnet of high field quality, shielded internally by a thick-walled pipe of tungsten with a cross section whose inner boundary hugged the 5-cm x 2-cm elliptical beam pipe and whose outer boundary was either rectangular or elliptical. Magnet-performance parameters were those of the more-challenging of the two combined-function magnets in a Yuri-Alexahin lattice [1] for the MAP 1.5-TeV Muon Collider: a dipole field of 9 T superposed on a quadrupole gradient of 80 T/m. The bore was either rectangular (Fig. 1a) or elliptical (Fig. 1b). A primary goal of the SBIR was to minimize the use of tungsten shielding and magnet conductor while limiting the wall power for refrigeration to remove the heat deposited in the cold mass by radiation from muon decay. We studied two shield and magnet concepts. One (Fig. 1a) has a shield of rectangular outer perimeter within a combined-function magnet consisting of a rectangular-block quadrupole within a rectangular-block dipole. The other concept (Fig. 1b) has a shield of elliptical cross section within a magnet consisting of a cos(2θ) quadrupole magnet within a cos(θ) dipole. The designs allocate 1 cm between the shield and coils for a pair of vacuum spaces and a thermal shield at liquid-nitrogen temperature.
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