title: Oscillations in the expansion of solid 4He into vacuum.
abstract: The particle flux through a micron-sized orifice into vacuum from a source chamber filled with solid 4He exhibits a striking sequence of periodic bursts. The period increases (decreases) with pressure (temperature), vanishing at the melting point for temperatures above the upper lambda point at 1.76 K. The oscillations are attributed to a periodic collapse of the solid induced by the accumulation of excess vacancies injected at the orifice and the period provides information on vacancy diffusivity. Dramatic deviations from this behavior below 1.76 K suggest important modifications in the flow properties of solid 4He induced by the excess vacancies.
authors.affiliation: Max-Planck-Institut für Dynamik und Selbstorganisation, Bunsenstrasse 10, 37073 Göttingen, Germany.
authors.forename: Giorgio
authors.initials: G
authors.lastname: Benedek
authors.forename: Franco
authors.initials: F
authors.lastname: Dalfovo
authors.forename: Robert E
authors.initials: RE
authors.lastname: Grisenti
authors.forename: Manuel
authors.initials: M
authors.lastname: Käsz
authors.forename: J Peter
authors.initials: JP
authors.lastname: Toennies