  A major focus of the global HEP community is on high field superconducting
magnets made of High Temperature Superconductors (HTS) for future Energy
Frontier Programs. Within the U.S. Magnet Development Program (US MDP), a key
task is that of developing HTS inserts producing fields larger than 5 T within
15 T outserts made of Nb$_3$Sn to generate 20 T+ for future accelerators.
Bi$_2$Sr$_2$CaCu$_2$O$_8$$_-$$_x$ (BiSCO) is the only high T c superconductor
available as an isotropic round multifilamentary wire, which is ideal for
producing the flat cables (i.e., Rutherford type cables) that are used in
accelerator magnets. Significant progress in the development and
industrialization of BiSCO wires has been made over the last decade. However,
several challenges remain for this HTS to be used successfully in hybrid
magnets. The following is required to improve performance, lower costs and
simplify the processing of BiSCO accelerator magnets: (1) The development and
design, in collaboration with industry, of BiSCO wires that are adequate for
Rutherford cabling; (2) The development of insulation processes and materials
that prevent leaks when heat treated in highly corrosive oxygen; (3) Control of
stresses and strains; and (4) Integration of high pressure heat treatment with
a new approach that will lower costs and simplify processing.
