Observation of an ultracold plasma instability

TL;DR

This paper reports the first observation of a high-frequency electron drift instability in an expanding ultracold plasma, characterized by periodic electron emission and density perturbations, linked to electron cyclotron dynamics.

Contribution

It provides the first experimental evidence of a specific plasma instability in ultracold conditions, linking electron drift waves to cyclotron harmonics.

Findings

Periodic electron emission observed in ultracold plasma

Electron density distribution shows strong perturbations

Identified as a high-frequency electron drift instability

Abstract

We present the first observation of an instability in an expanding ultracold plasma. We observe periodic emission of electrons from an ultracold plasma in weak, crossed magnetic and electric fields, and a strongly perturbed electron density distribution in electron time-of-flight projection images. We identify this instability as a high-frequency electron drift instability due to the coupling between the electron drift wave and electron cyclotron harmonic, which has large wavenumbers corresponding to wavelengths close to the electron gyroradius.