Collapse of Vapor-Filled Multielectron Bubbles Held Against a Surface

Multielectron bubbles (MEBs) are cavities in liquid helium containing a layer of electrons pinned to the inner surface of the bubbles. Previous experimental work carried out with MEBs in bulk helium-4 above the lambda point showed MEBs can contain vapor, which condenses in a time approximately proportional to the volume of the bubble, and this observation was further confirmed by numerical simulations. In the present work, we describe experiments where the MEBs are held against a solid substrate. We found the rate of vapor condensation and therefore the speed of collapse of the bubble to be orders of magnitude faster compared to MEBs in bulk. We discuss a numerical model and the associated difficulties to explain this difference.