title: Observation of an ultracold plasma 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 wave numbers corresponding to wavelengths close to the electron gyroradius.
authors.affiliation: Joint Quantum Institute, University of Maryland, College Park, Maryland 20742, USA.
authors.forename: X L
authors.initials: XL
authors.lastname: Zhang
authors.forename: R S
authors.initials: RS
authors.lastname: Fletcher
authors.forename: S L
authors.initials: SL
authors.lastname: Rolston