Magnesium Diboide Superconducting Coils for Adiabatic Demagnetization Refrigerators (ADR's)

For Adiabatic Demagnetization Refrigerators (ADRs) in space applications, it is desirable to have very light weight, small diameter, high current density superconducting wires that can operate at temperatures in the 10-30 K range, specifically with engineering current densities in the 50,000-100,000 A/cm2 range, at 15K in 3 tesla fields. Magnesium diboride, a light-weight superconductor wire, is the ideal candidate coil material for ADRs in the 10-30 K range. During the Phase I we demonstrated that drawing magnesium diboride wires to the needed diameter range could be achieved. However to meet the most desired application requirements we need slight improvement in superconductor current density, reduction of powder filament size, and higher percent superconductor fraction at the desired wire diameter range of 0.075 mm - 0.150 mm. In the Phase II effort we propose a development plan to make these improvements to small diameter magnesium diboride wire and to demonstrate conductor performance over long length on small coils.