EISCAT (European Incoherent Scattter) studies the interaction between the Sun and the Earth as revealed by disturbances in the magnetosphere and the ionised parts of the atmosphere (these interactions also give rise to the spectacular aurora, or Northern Lights). The radars are operated in both Common and Special Programme modes, depending on the particular research objective, and Special Programme time is accounted and distributed between the Associates according to rules which are published from time to time.

One EISCAT transmitter site is located close to the city of Tromsø, in Norway, and additional receiver stations are located in Sodankylä, Finland, and Kiruna, Sweden. See an animation that shows the basic operation. The EISCAT Headquarters are also located in Kiruna. 1996 the EISCAT Scientific Association constructed a second incoherent scatter radar facility, the EISCAT Svalbard Radar, near Longyearbyen on the island of Spitsbergen, far to the North of the Norwegian mainland.

The Incoherent Scatter Radar technique requires sophisticated technology and EISCAT engineers are constantly involved in upgrading the systems.

In addition to the incoherent scatter radars, EISCAT also operates an Ionospheric Heater facility at Ramfjordmoen (including a Dynasonde) to support various active plasma physics experiments in the high latitude ionosphere. 

SOURCE ARTICLE

EISCAT New Home Page
..z

The Heating facility is situated next to the UHF and VHF incoherent scatter radars. See the list of publications that have come out of this facility since its construction in 1979.

The Heater is used for ionospheric modification experiments applying high-power transmissions of high-frequency electro-magnetic waves to study plasma parameters in the ionosphere. The name Heating stems from the fact that these high power electromagnetic waves, which are transmitted into the ionosphre with high-gain atennas, heat the electrons and thus modify the plasma state. To create plasma turbulence, the transmitted frequencies have to be close to the plasma resonances, which are 4 to 8 MHz. 

SOURCE ARTICLE

Abstract

It is well known that the electric field of a high power HF wave transmitted into the ionosphere will interact with the free electrons in the plasma by causing them to oscillate at the same frequency as the transmitted wave, and then to re-emit other electromagnetic waves, with frequencies near the original wave, but with the power in the new emission being much weaker than the original. This effect is known as stimulated electromagnetic emission, or SEE. On 11 and 12 November 2001, high power HF radio wave heating experiments were carried out in the ionosphere above the EISCAT observatory near Tromsø, Norway. Optical observations revealed artificial aurora in the form of rings, which lasted for several seconds before collapsing into blobs, while at the same time descending in altitude, and then disappearing. During this experiment SEE were recorded on a traditional spectrum analyzer system; this can tell us information about the relationship between the auroral rings and the local electron gyrofrequency, and thus help to determine why the rings occur. The geometry of the rings suggests a dependence of the emissions to the angle with respect to the geomagnetic field, or possibly to the spatial gradient in the HF radio wave pump beam. An angular dependence in the artificial excitation of enhanced ion-acoustic and Langmuir waves has also been seen in incoherent scatter radar (ISR) observations. In an attempt to determine if such a dependence exists in SEE, an interferometric SEE system is being developed and will be described. ISR observes Langmuir turbulence and SEE is a result of upper hybrid turbulence, either of which may accelerate electrons and produce optical emissions. The combination of angle-sensitive SEE and ISR observations, along with other available measurements, will thus help to determine if the optical emissions are due primarily to one type of turbulence or to a combination of both.

SOURCE DOCUMENT
..

EISCAT has an UHF antenna in Sodankylä which receives signals from Tromsø. The people working here are employed by University Of Oulu through Sodankylä Geophysical Observatory.

The EISCAT Scientific Association is an international research organisation operating three geophysical research Incoherent Scatter Radar systems, an Ionospheric Heater and a Dynasonde in Northern Scandinavia. In November 1992, it was decided to build a Radar on Svalbard, and 1994 the EISCAT Svalbard Radar was ready, standing near Longyearbyen on Svalbard. It is a fully steerable 32 m parabolic dish antenna, as seen on the picture below

Welcome to Kiruna!
EISCAT's site lies about 15 km west from Kiruna city. It consists of a small control building and the UHF receiver antenna. It receives the signals transmitted by the Tromsø Radar. The people working here are employed by Swedish Institute of Space Physics.
..