New measurements of critical data of optimized NBTi superconductors

The critical data j
c
and B
c2
of NbTi based alloy s.c. material (Ti contents between 39 and 52 wt %) have been determined in the range from 4.2 to 1.8 K. In the case of optimized pinning structure the results are in good accordance with the function B
c2
(T) = B
c2
(O)(1-t
²
). The current density can be described by the scaling law F
p
=c.B
c2
^3.5
b(1-b). The stabilisation parameter T
o
(as a function of B and T) is derived from the experimental data. Technical aspects concerning the application of s.c. material are discussed.