THE EFFECT OF ROUGH SURFACES ON THE STABILITY OF SUPERCOOLED HE-3-A

We have studied the first order A-B phase transition in superfluid He- 3 in 'rough' surface morphologies. Surfaces which present a small radi us of curvature to tile supercooled A-phase decrease the barrier to B- phase nucleation. preliminary data indicate that the lifetime for the supercooled A-phase at T approximate to 0.56T(c) is substantially decr eased when ionizing radation acts in concert with specific surface rou ghnesses. We have observed for the first time B-phase nucleation coinc ident with mechanical vibrations in tubes containing specific surface roughness. Also, we show that in the absence of a strong magnetic fiel d the A-B interface can be prevented from entering a smooth-walled tub e by a membrane filter of sub-micron pore diameter.