Millimeter wave scattering and diffraction in 110 GHz air breakdown plasma

Journal Article · Mon Apr 15 04:00:00 EDT 2013 · Physics of Plasmas

DOI:https://doi.org/10.1063/1.4798424· OSTI ID:22130477

Cook, Alan M.; Hummelt, Jason S.; Shapiro, Michael A.; Temkin, Richard J. ^[1]

---

1. Plasma Science and Fusion Center, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139 (United States)

We present measurements of the scattering, reflection, absorption, and transmission of a 1.5 MW, 110 GHz quasioptical gyrotron beam by a self-induced air breakdown plasma. The breakdown forms a periodic array of plasma filaments, oriented parallel to the incident electric field polarization that propagates toward the microwave source. For incident intensity of 3 MW/cm{sup 2}, calorimetric measurements show that as much as 45% of the full beam power is absorbed by the plasma, averaged over the pulse, 1% is reflected backward, and the remainder is transmitted and also scattered into a wide angular spread. We observe that approximately 10 times more power is scattered in the direction perpendicular to the filaments than parallel. The far-field angular distribution of transmitted power exhibits a diffraction pattern that changes throughout the 2-{mu}s life of the plasma.

• OSTI ID: 22130477
• Journal Information: Physics of Plasmas, Journal Name: Physics of Plasmas Journal Issue: 4 Vol. 20; ISSN PHPAEN; ISSN 1070-664X
• Country of Publication: United States
• Language: English

Related Subjects

70 PLASMA PHYSICS AND FUSION TECHNOLOGY
ABSORPTION
AIR
ANGULAR DISTRIBUTION
APPROXIMATIONS
BREAKDOWN
CALORIMETRY
DIFFRACTION
ELECTRIC FIELDS
GHZ RANGE
MICROWAVE AMPLIFIERS
MICROWAVE RADIATION
PERIODICITY
PLASMA DIAGNOSTICS
PLASMA FILAMENT
WAVE PROPAGATION