Observation of large arrays of plasma filaments in air breakdown by 1.5-MW 110-GHz gyrotron pulses.
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.
Hidaka
Yoshiteru
Y
Plasma Science and Fusion Center, Massachusetts Institute of Technology, 167 Albany Street, Cambridge, MA 02139, USA.
Choi
E M
EM
Mastovsky
I
I
Shapiro
M A
MA
Sirigiri
J R
JR
Temkin
R J
RJ