NUCLEATION OF BUBBLES ON QUANTIZED VORTICES IN HE-4

We consider the properties of vortices in superfluid helium-4 at negat ive pressure. Based on a simple density-functional model, we first cal culate the density profile in the vicinity of a vortex. We then determ ine the negative pressure at which the vortex becomes unstable against a uniform radial expansion all along its length. This instability occ urs at -6.9 bars. We then calculate the pressure-dependence of the ene rgy DELTAE(nuc) required to nucleate a bubble on the vortex. The resul ts of this calculation are used to estimate the effect of quantized vo rtices on the rate at which bubbles are nucleated in superfluid helium at negative pressure.