title: Observation of large arrays of plasma filaments in air breakdown by 1.5-MW 110-GHz gyrotron pulses.
abstract: We report the observation of two-dimensional plasma filamentary arrays with more than 100 elements generated during breakdown of air at atmospheric pressure by a focused Gaussian beam from a 1.5-MW, 110-GHz gyrotron operating in 3-micros pulses. Each element is a plasma filament elongated in the electric field direction and regularly spaced about one-quarter wavelength apart in the plane perpendicular to the electric field. The development of the array is explained as a result of diffraction of the beam around the filaments, leading to the sequential generation of high intensity spots, at which new filaments are created, about a quarter wavelength upstream from each existing filament. Electromagnetic wave simulations corroborate this explanation and show very good correlation to the observed pattern of filaments.
authors.affiliation: Plasma Science and Fusion Center, Massachusetts Institute of Technology, 167 Albany Street, Cambridge, MA 02139, USA.
authors.forename: Yoshiteru
authors.initials: Y
authors.lastname: Hidaka
authors.forename: E M
authors.initials: EM
authors.lastname: Choi
authors.forename: I
authors.initials: I
authors.lastname: Mastovsky
authors.forename: M A
authors.initials: MA
authors.lastname: Shapiro
authors.forename: J R
authors.initials: JR
authors.lastname: Sirigiri
authors.forename: R J
authors.initials: RJ
authors.lastname: Temkin