Temporal evolution of pump beam self-focusing at the High-Frequency Active Auroral Research Program

摘要: [1] On 4 February 2005 the High-Frequency Active Auroral Research Program (HAARP) facility was operated at 2.85 MHz to produce artificial optical emissions in ionosphere while passing through second electron gyroharmonic. All-sky recordings were performed with 15 s integration, alternating between 557.7 and 630 nm. We report first observations showing temporal evolution of large-scale pump wave self-focusing magnetic zenith, observed nm images. These clearly show that maximum intensity not reached after pumping, which is unexpected since emission delay time <1 s, signature had intensified a much smaller region within beam 45 pumping. In addition, adjacent regions lost intensity. Radar measurements indicate plasma depletion ∼1% near HF reflection altitude. Ray tracing region, forms concave reflecting radio mirror, reproduces spatial morphology. A flux density gain up ∼30 dB may occur. ray trace consistent for critical frequencies down ∼0.5 below frequency.