Magnetic Zenith Enhancement of HF Radio-Induced Airglow Production at HAARP
Abstract
Airglow production at various beam positions relative to the magnetic field was investigated as part of an optics campaign at HAARP in February 2002. Strong emissions up to several hundred Rayleigh at 630.0 nanometers and more than 50 R at 557.7 nanometers were produced in a small spot approximately 6 inches diameter located near the magnetic zenith when the transmitter beam was directed up the magnetic field. This effect was observed hundreds of times over a wide range of frequencies and ionospheric conditions. The spot at HAARP appears on average just equatorward of the nominal magnetic field direction, deflects somewhat toward the beam center when the beam is scanned, and varies slightly in size with transmitter frequency. Red-to-green ratios as low as 3 were observed, with both wavelengths showing significant onset delay. Identifiable enhancements in red-line emission were produced down to 2 MW ERP in a power ramp experiment.
Document Details
- Document Type
- Technical Report
- Publication Date
- Feb 22, 2003
- Accession Number
- ADA515734
Entities
People
- A. Gurevich
- C. Selcher
- D. Sentman
- E. Gerken
- H. C. Carlson
- M. McCarrick
- T. R. Pedersen
Organizations
- Air Force Research Laboratory