Axial mechanical properties of epoxy impregnated superconducting solenoids at 4.2 K

Abstract

The mechanical properties of superconducting solenoids along their longitudinal axes were characterized at 4.2 K through a series of tests on small epoxy impregnated coils. Three coil configurations were manufactured which consisted of two layers of either Nb/sub 3/Sn or NbTi. The Nb/sub 3/Sn conductor was insulated with E-Glass fiber braid insulation and the NbTi conductor was insulated with either polyester braid or Polyvinylformal (FORMVAR). Characteristics including the elastic modulus, allowable compressive stress, cyclic loading behavior, and, of primary interest, ultimate tensile strength were measured. Samples were compressed to 200 MPa and fatigued 100 cycles from -125 MPa to 25 MPa. The tensile strengths are shown to be dependent of the insulation material and range from 51.9 MPa to 62.8 MPa.