title: Ionospheric modification at twice the electron cyclotron frequency.
abstract: In 2004, a new transmission band was added to the HAARP high-frequency ionospheric modification facility that encompasses the second electron cyclotron harmonic at altitudes between approximately 220 and 330 km. Initial observations indicate that greatly enhanced airglow occurs whenever the transmission frequency approximately matches the second electron cyclotron harmonic at the height of the upper hybrid resonance. This is the reverse of what happens at higher electron cyclotron harmonics. The measured optical emissions confirm the presence of accelerated electrons in the plasma.
authors.affiliation: Geospace Research, Inc., El Segundo, California 90245, USA.
authors.forename: F T
authors.initials: FT
authors.lastname: Djuth
authors.forename: T R
authors.initials: TR
authors.lastname: Pedersen
authors.forename: E A
authors.initials: EA
authors.lastname: Gerken
authors.forename: P A
authors.initials: PA
authors.lastname: Bernhardt
authors.forename: C A
authors.initials: CA
authors.lastname: Selcher
authors.forename: W A
authors.initials: WA
authors.lastname: Bristow
authors.forename: M J
authors.initials: MJ
authors.lastname: Kosch