Antenna 1 Transmitter EISCAT-3D as a diagnostic for ionospheric heating experiments Michael Rietveld EISCAT Scientific Association TromsøNorway

© EISCAT Scientific Association Tony van Eyken Tokyo, May 2007 Norway-Japan Symposium onPolar, Space, and Climate Research Tromsø HEATING facility 12, 100-kW vacuum tube amplifiers, class AB temporary use as receive-only array

The facility started operation in 1980The facility started operation in 1980 It runs about 200 hours a yearIt runs about 200 hours a year So it can probably run another 10 years or so without major repair costs.So it can probably run another 10 years or so without major repair costs. The low-power RF generation and control software has just been upgraded (DDS synthesizers- faster frequency changes)The low-power RF generation and control software has just been upgraded (DDS synthesizers- faster frequency changes) We are investigating operation at the 2nd gyroharmonic (2.71 MHz)We are investigating operation at the 2nd gyroharmonic (2.71 MHz)

Wide-field (>beam width) radar imaging/scanning as well as narrow field will probably find new phenomena, as it did for optical diagnostics in 's experiments used narrow field photometers that often were pointed to the wrong place and so we missed out on images like this, until ALIS and DASI came along.

Topside Z-mode effect and the radio window Ashrafi, Kosch et al., work in progress Vertically localised strong backscatter (range bins ca. 2 km apart) Horizontally localised strong backscatter (antenna positions 1° apart, 30s in time) strong backscatter = coherent echoes

Heating requirements of E3D Coherent Echo resolutions Incoherent Scatter resolutions RegionHeighttimehorizHeighttimeHoriz* 85 km < 100m 100ms30m 1 km 1-10s 110 km 100m 10 ms 100m 1 km 1s10m* 250 km 100m 10 ms 100m 1-2 km 1s10m* ThroughInterferometry * = perpendicular to B, i.e. ca. 13°tilt to south

Characteristics of Heating phenomena Langmuir turbulence has time scales of milliseconds; thermal effects in the F region seconds. Horizontal Spatial scales of excited phenomena range from 10’s of m to ~100 km Many phenomena show a strong geometrical dependence on angle to the geomagnetic field. requiring volumetric imaging of the ionosphere within ± ca. 15° of HF beam direction. requiring volumetric imaging of the ionosphere within ± ca. 15° of HF beam direction.

Strong (coherent) signals vary on 100’s m scale in altitude at >200 km Cavitation spectra decay line first cascade second cascade

GYROHARMONICEffects ca. 100 km N-S extent coherent backscatter, horizontal look.

Many F-region phenomena show a very strong dependence on the angle between the HF wave and the geomagnetic field For the E region (<200km) there has never been documented any such dependence.

© EISCAT Scientific Association Tony van Eyken Tokyo, May 2007 Norway-Japan Symposium onPolar, Space, and Climate Research Electron heating and UHF beam swinging 7 Oct MHz ERP = 100 MW O-mode ( Rietveld et al., JGR, 2003 )

Where should the E3D core be situated ? At/near Ramfjordmoen because: * We can easily observe along B * (Have common infrastructure) Away from Ramfjordmoen because: * Broad-band noise from faulty heater coaxial-lines can interfere with VHF measurements * Power level changes from heater modulation can affect radar transmitter power (Both these are merely 'annoyances' rather than 'science killers')

To measure field-aligned km

If the core is built elsewhere, should we: move Heating or build a new heater ? One could move the 30-yr old transmitters but antennas and feeds need rebuilding. If so, will we have the money ?