Thermal strain in superconducting NbSn strand at cryogenic temperature

Harjo, S.   ; Kawasaki, Takuro   ; Hemmi, Tsutomu; Ito, Takayoshi*; Nakamoto, Tatsushi*; Aizawa, Kazuya  

Measurements of thermal strains in the superconducting constituent (NbSn phase) in NbSn strand were performed using BL19 Takumi of MLF, J-PARC. Lattice parameters of NbSn phase change continuously with increasing temperature. To avoid the thermal expansion effect, lattice parameters of the filaments (extracted from the strand) measured at the same temperatures were used to estimate the thermal strains in NbSn phase. As results, thermal strains for axial direction below 50 K are kept roughly constant at large compressive values, while the values are much lower (the difference is 0.13%) than that measured at room temperature.