Artificial Ionospheric Layers during Pump Frequency Stepping Near the 4th Gyroharmonic at HAARP

Abstract

We report on artificial descending plasma layers created in the ionosphere F region by high-power high-frequency (HF) radio waves from High-frequency Active Auroral Research Program at frequencies f(0) near the fourth electron gyroharmonic 4f(ce). The data come from concurrent measurements of the secondary escaping radiation from the HF-pumped ionosphere, also known as stimulated electromagnetic emission, reflected probing signals at f(0), and plasma line radar echoes. The artificial layers appeared only for injections along the magnetic field and f(0)>4f(ce) at the nominal HF interaction altitude in the background ionosphere. Their average downward speed ~0.5 km/s holds until the terminal altitude where the local fourth gyroharmonic matches f(0). The total descent increases with the nominal offset f(0)-4f(ce).

Artificial ionospheric layers driven by high‐frequency radiowaves: An assessment

“…By the same token, in the daytime/ twilight experiments Sergeev et al, 2013] DL started well before striations could develop. However, the DL in Sergeev et al's [2013] experiments were observed only for f 0 > 4f ce , consistent with Gustavsson et al's [2006] observations of stronger 427.8 nm emissions at f 0 > 4f ce . Thus, the DL formation has been explained in terms of an ionizing wavefront created by the SLT-accelerated electrons [Mishin and Pedersen, 2011;Eliasson et al, 2012.…”

“…First, the OTSI UH Lo [Kuo et al, 1997] of the primary UH waves with the r.m.s. This helps to explain the emergence of DL [Sergeev et al, 2013], faster descent speeds in Figure 6, and intensification of 427.8 nm emissions [Gustavsson et al, 2006] These are transferred into long scales via parametric interactions, e.g., induced scattering on ions.…”

“…In addition to the HAARP modular UHF incoherent scatter radar (MUIR) and optical imagers, Pedersen et al [2009Pedersen et al [ , 2010Pedersen et al [ , 2011 used the HAARP ionosonde to reveal that descending layers (hereafter, DL) are patches of newly ionized plasma. Sergeev et al [2013] explored DL using concurrent measurements of SEE, reflected probing signals, and MUIR plasma line (PL) backscatter during frequency-stepping experiments around 4f ce . The DL-associated optical emissions at ≈732 nm and 427.8 nm (the blue line) indicate electron acceleration above the ionization energies ion [Pedersen et al, 2010;Hysell et al, 2014].…”

Modification of the High-Latitude Ionospheric F Region By High-Power HF Radio Waves at Frequencies Near the fifth and Sixth Electron Gyroharmonics

“…Например, в экспериментах на нагревном стенде HAARP при воздействии на ионосферу мощных радиоволн на частотах, близких к 4-й гармонике электронной циклотронной частоты f ce , обнаружено и исследовано образование слоя искусственной ионизации, опускающегося на 5-30 км от уровня отражения волны накачки до высот локального двойного резонанса [9,10]. На том же стенде, по наблюдениям искусственного радиоизлучения ионосферы (ИРИ) при нагреве на частотах возле третьей и четвертой гармоник электронной гирочастоты исследованы спектры ИРИ, возбуждаемые в диапазоне ионных акустических волн и около гармоник ионной гирочастоты [11].…”

Incidence angle dependence of Langmuir turbulence and artificial ionospheric layers driven by high-power HF-heating

“…The simulation results reproduce the salient observational features of ionization fronts descending from about 230 km to 150 km in a few minutes. While the simulation studies of Eliasson et al (2012) was carried out for vertical incidence of the electromagnetic wave, the experiments (Pedersen et al 2010;Mishin and Pedersen, 2011;Sergeev et al 2013) were conducted with the HF radio beam centered at the magnetic zenith, which is 14.5 degrees south to the vertical at HAARP. Early experiments have also shown enhanced electron heating and incoherent radar backscatter near MZ (e.g., Kosch et al 2000;Pedersen et al 2003;Rietveld et al 2003).…”