Novel Methods to Create Multielectron Bubbles in Superfluid Helium

TL;DR

This paper introduces two methods for creating multielectron bubbles in superfluid helium, including a novel extraction technique that enables detailed study of their properties and behaviors.

Contribution

It presents a new method to generate multielectron bubbles using electric fields and analyzes their discharge mechanisms, advancing understanding of their formation and stability.

Findings

Multielectron bubbles can be created by applying high electric fields.

Charges up to 1.6x10^-9 C (~10^10 electrons) were measured.

Analytical explanation for short-lived bubbles discharging via tunneling.

Abstract

An equilibrium multielectron bubble in liquid helium is a fascinating object with a spherical two-dimensional electron gas on its surface. We describe two ways of creating them. MEBs have been observed in the dome of a cylindrical cell with an unexpectedly short lifetime; we show analytically why these MEBs can discharge by tunneling. Using a novel method, MEBs have been extracted from a vapor sheath around a hot filament in superfluid helium by applying electric fields up to 15 kV/cm, and photographed with high-speed video. Charges as high as 1.6x10-9 C (~1010 electrons) have been measured. The latter method provides a means of capture in an electromagnetic trap to allow the study of the extensive exciting properties of these elusive objects.