Ionospheric heater
An ionospheric heater or high frequency ionospheric pump is a heating system for the magnetized plasma in the ionosphere . It consists of a powerful radio wave transmitter on the earth's surface to irradiate the plasma.
Such systems are used to study plasma turbulence in the ionosphere and the upper atmosphere. The irradiation of the ionosphere causes the magnetized plasma there to heat up mainly through the so-called upper hybrid resonance (see also plasma oscillation ), which heats the electrons and thereby accelerates the ions. The systems transmit with a steep-beam antenna field in the shortwave range (3 to 30 MHz), in which radio waves from the ionosphere are reflected back to the ground. With them, a series of plasma turbulence phenomena can be caused in a conditionally controllable manner from the ground if the ionosphere is naturally calm and not influenced by magnetic field disturbances. This active research method complements passive observations of naturally induced phenomena when exploring the ionosphere and upper atmosphere.
The researched plasma turbulence phenomena include different types of non-linear wave interactions, in which different waves are superimposed in the plasma and interact with the transmitted radio waves, the formation and build-up of fiber-like plasma structures and electron acceleration. The turbulence can be observed using incoherent backscatter radar by measuring its weak electromagnetic emissions or visible light emissions. The visible emissions result from the excitation of atmospheric atoms and molecules by electrons, which were accelerated in the plasma turbulence. Since this process is the same as with the northern lights , the visible emissions have sometimes been referred to as artificial northern lights, whereby sensitive cameras are required for detection, which is not the case with real northern lights.
Ionospheric heaters must be sufficiently powerful to allow the study of plasma turbulence, with any penetrating radio radiation affecting the ionosphere by accelerating the electrons. Although the research facilities have powerful transmitters, the energy flow in the ionosphere in the most powerful facility (HAARP) remains below 0.03 W / m 2 . This results in an energy density in the ionosphere that is less than a hundredth of the usual thermal energy density of the ionospheric plasma. The energy flow can also be compared with that of solar radiation on the earth's surface, which is around 1.5 kW / m 2 . During aurora activity, ionospheric heaters generally cannot trigger any ionospheric effects because the radiation is largely swallowed by the naturally excited ionosphere.
The fact that radio waves influence the ionosphere was discovered back in the 1930s with the Luxembourg effect . Ionospheric heaters have been experimenting with since the early 1970s.
Active ionospheric heaters
- the system on Ramfjordheide near Tromsø in Norway , operated by the European Incoherent Scatter Scientific Association (EISCAT), capable of a radiation output of 1.2 MW or more than 1 GW effective radiation output (ERP)
- Space Plasma Exploration by Active Radar (SPEAR) is a system operated by the University Center in Svalbard (UNIS) alongside the EISCAT systems near Longyearbyen on Svalbard , capable of a radiation output of 192 kW or 28 MW ERP.
- the Sura plant in Wassilsursk near Nizhny Novgorod in Russia , capable of a radiation output of 750 kW or 190 MW ERP
- the system of the High Frequency Active Auroral Research Program (HAARP) north of Gakona (Alaska) , capable of a radiation output of 3.6 MW or 4 GW ERP
- HIgh Power Auroral Stimulation Observatory ( HIPAS ) northeast of Fairbanks, Alaska, capable of a radiation output of 1.2 MW or 70 MW ERP
Individual evidence
- ↑ a b TB Leyser, AY Wong: Powerful electromagnetic waves for active environmental research in geospace . In: Reviews of Geophysics , Vol. 47, 2009, RG1001.
- ↑ MJ Kosch, Y. Ogawa, MT Rietveld, S. Nozawa, R. Fujii: An analysis of pump-induced artificial ionospheric ion upwelling at EISCAT
- ↑ a b CJ Bryers, MJ Kosch, A. Senior, MT Rietveld, TK Yeoman: The thresholds of ionospheric plasma instabilities pumped by high-frequency radio waves at EISCAT . In: Journal of Geophysical Research: Space Physics . tape 118 , no. 11 , November 27, 2013, p. 7472–7481 , doi : 10.1002 / 2013JA019429 (English, wiley.com ).
- ↑ HAARP Fact Sheet ( Memento from May 15, 2013 in the Internet Archive )
- ↑ Basic information about EISCAT ( Memento from April 28, 2012 in the Internet Archive )
- ↑ High Latitude HF Induced Plasma Turbulence ( Memento from November 8, 2011 in the Internet Archive )
- ↑ Space Plasma Exploration by Active Radar ( Memento of the original from September 11, 2008 in the Internet Archive ) Info: The archive link was automatically inserted and not yet checked. Please check the original and archive link according to the instructions and then remove this notice.
