Nb/sub 3/Ge films fabricated by magnetron sputtering at substrate temperatures T/sub s/, from 600 to 850/sup 0/C and film thicknesses of 1 to 5 ..mu..m have been analyzed with respect to transition temperature T/sub c/, critical current density as a function of applied field J/sub c/(H), and grain size. J/sub c/ at 5Tesla shows a strong dependence on T/sub s/, decreasing by more than an order of magnitude as T/sub s/ increases from 700 to 815/sup 0/C. This decrease will be related to grain diameter D. Results will be presented which suggest a lower J/sub c/(H) in thicker films prepared at a fixed T/sub s/ is caused by increased grain diameters as the films grow in thickness. Evidence will be presented showing these results to be consistent with grain boundaries being the dominant pinning mechanism in these films.

A solenoid coil, 105 cm inside the 167 cm outside diameter, has been constructed and tested to study the performance of the stabilized Nb--Ti conductor to be used in the Mirror Fusion Test Facility (MFTF) being built at Lawrence Livermore Laboratory. The insulation system of the test coil is identical to that envisioned for MFTF. Cold-weld joints were made in the conductor at the start and finish of each layer; heaters were fitted to some of these joints and also to the conductor at various locations in the winding. This paper gives details of the construction of the coil and the results of the tests carried out to determine its propagation and recovery characteristics.

The principal objectives of the SLPX (Superconducting Long-Pulse Experiment) are: (1) to demonstrate quasi-steady operation of 3 to 5 MA hydrogen and deuterium tokamak plasmas at high temperature and high thermal wall loading, and (2) to develop reliable operation of prototypical tokamak reactor magnetics systems featuring a toroidal assembly of high-field niobium-tin coils, and a system of pulsed niobium-titanium superconducting poloidal-field coils. This paper describes the status of the engineering design features of the SLPX, with emphasis on the magnetics systems. The toroidal-field coils have an aperture of 3.1 x 4.8 m and can operate with a maximum field at the conductor of 12 T. The superconducting poloidal field magnetics system consists of a pulsed NbTi central solenoid and a set of dc NbTi equilibrium-field coils. The entire machine is enclosed in an outer vacuum container equipped with re-entrant ports that provide ambient access to the room-temperature plasma vessel.