Thermionic Emission, Multielectron Bubbles, and A Novel Electron Collector in a Liquid Helium Environment

TL;DR

This paper explores methods for generating electrons in liquid helium using thermionic emission and glowing filaments, introduces a new electron collector, and reports on creating multi-electron bubbles with potential applications in low-temperature physics.

Contribution

It presents novel techniques for electron generation and collection in liquid helium, including a new vapor-phase electron collector and a method for producing multi-electron bubbles.

Findings

Electron emission curves show negative differential resistance.

A new low-temperature vapor-phase electron collector was developed.

Multi-electron bubbles were successfully produced in liquid helium.

Abstract

We study two techniques to create electrons in a liquid helium environment. One is thermionic emission of tungsten filaments in a low temperature cell in the vapor phase with a superfluid helium film covering all surfaces; the other is operating a glowing filament immersed in bulk liquid helium. We present both the steady state and rapid sweep I-V curves and the electron current yield. These curves, having a negative dynamic resistance region, differ remarkably from those of a vacuum tube filament. A novel low temperature vapor-phase electron collector for which the insulating helium film on the collector surface can be removed is used to measure emission current. We also discuss our achievement of producing multi-electron bubbles (MEBs) in liquid helium by a new method.