Antenna 1

Antenna 2

Antenna 3

TransmitterControl

EISCAT-3D and active EISCAT-3D and active ionospheric experiments ionospheric experiments

Michael RietveldMichael Rietveld

EISCAT Scientific AssociationEISCAT Scientific Association

TromsøTromsø

NorwayNorway

Tromsø HEATING facilityTromsø HEATING facility

12, 100-kW 12, 100-kW vacuum tube vacuum tube amplifiers, amplifiers, class ABclass AB

temporary use as temporary use as receive-only arrayreceive-only array

• Heating can produce Heating can produce high electron high electron temperatures and temperatures and artificial light artificial light emission. emission.

Gustavsson et al, PRL, 2006

Intensity of red line

Intensity of green line

Electron temperature

The artificial auroral structure at 16:37:05 UT on12 November 2001, 5 s after HF pump turn on. Integration time =5 s. The image is taken in the zenith from Skibotn and has a 50º field of view (large circle). The -3 dB locus of the pump beam assuming free space propagation is shown as a small circle (beamwidth = 7.4º), projected at 230 km altitude and tilted 9º south of the HF facility at Ramfjordmoen. The upper cross shows the location of the HF transmitter whilst the lower cross shows the magnetic field line direction (12.8º S), both projected at 230 km. The dotted line represents the magnetic field line connected to Ramfjordmoen and the labels give altitude. (from Kosch et al., GRL, 2004)

•The facility started operation in 1980The facility started operation in 1980

•It runs only about 200 hours a yearIt runs only about 200 hours a year

•So it can probably run another 10 years or So it can probably run another 10 years or so without major repair costs.so without major repair costs.

•The low-power RF generation and control The low-power RF generation and control software has just been upgraded (DDS software has just been upgraded (DDS synthesizers- faster frequency changes)synthesizers- faster frequency changes)

•We are investigating operation at the 2nd We are investigating operation at the 2nd gyroharmonic (2.71 MHz)gyroharmonic (2.71 MHz)

Characteristics of Heating phenomena 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 requiring volumetric imaging of the ionosphere within within ±± ca. 15 ca. 15° of HF beam direction, ° of HF beam direction,

like EISCAT-3D could dolike EISCAT-3D could do

Topside Z-mode effect and the radio Topside Z-mode effect and the radio windowwindow

Ashrafi, Kosch et al., work in progressAshrafi, Kosch et al., work in progress

Vertically localised Vertically localised strong strong backscatterbackscatter (range bins (range bins ca. 2 km apart)ca. 2 km apart)

Horizontally localised Horizontally localised strong strong backscatterbackscatter (antenna positions (antenna positions 11°° apart, 30s in time) apart, 30s in time)

strong backscatterstrong backscatter = coherent echoes = coherent echoes

PMSE overshoot immediately after switching the 20s long heater pulse off.

Raw data

Total PMSE intensity (sum of highest intensities at each time sample)

Smoothed data

The background noise on this linear scale is at approximately 2500. (from Havnes et al., GRL, 30, 2229, 2003.)

20s20s160s160s

•Weaker than PMSE

•Lower altitude than PMSE

•Not associated with NLC

•Not during extreme cooling

Polar Mesospheric Winter Echoes Polar Mesospheric Winter Echoes (PMWE)(PMWE)

Want:Want:

Incoherent scatter spectra from 60-90 km with good (100’s m) spatial resolutionIncoherent scatter spectra from 60-90 km with good (100’s m) spatial resolution

(to measue Te changes, and electron density bite-outs associated with PMSE)(to measue Te changes, and electron density bite-outs associated with PMSE)