Expansion of Solid Helium into Vacuum: the Geyser Effect

TL;DR

This paper investigates a geyser-like periodic flux of solid helium into vacuum, attributing it to vacancy-induced collapses within the solid, and provides insights into vacancy diffusivity through kinetic modeling.

Contribution

It introduces a novel geyser effect in solid helium and links it to vacancy dynamics, offering a new understanding of vacancy behavior in quantum solids.

Findings

Observed periodic helium flux resembling a geyser.

Flux curves match a kinetic model of vacancy collapse.

Provided direct estimates of vacancy diffusivity in solid helium.

Abstract

The particle flux through a two micron diameter orifice into vacuum from a source chamber filled with solid He exhibits a striking periodic behavior similar to that of a geyser. This phenomenon is attributed to a periodic collapse of the solid inside the source induced by the accumulation of excess vacancies injected at the orifice. The flux-time curves agree well with a kinetic model and provide direct information on the diffusivity of vacancies in solid He.