−43He mixture as a weak link for Josephson effects in superfluidHe3

We discuss the Josephson current for a special weak-link arrangement in superfluid ${}_{}{}^3{}_{}{}^{}\mathit{B}$. The weak link is made out of a ${}_{}{}^3{}_{}{}^{}\mathrm{-}_{}^4{}_{}{}^{}$He mixture which separates two regions of pure ${}_{}{}^3{}_{}{}^{}\mathrm{He}$. For large separations (D≫${\xi }_m$) we find Josephson’s current-phase relation J=${\mathrm{nv}}_c$ sinφ, and calculate the critical velocity $v_c$.