Antenna 1Transmitter

EISCAT-3D as a diagnostic for EISCAT-3D as a diagnostic for ionospheric heating experiments ionospheric heating experiments

Michael RietveldMichael Rietveld

EISCAT Scientific AssociationEISCAT Scientific Association

TromsøTromsø

NorwayNorway

Tokyo, 29-30 May 2007

Norway-Japan Symposium onPolar, Space, and Climate Research

© EISCAT Scientific Association Tony van Eyken 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

•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 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)

Wide-field (>beam width) radar Wide-field (>beam width) radar imaging/scanning as well as narrow field will imaging/scanning as well as narrow field will probably find new phenomena, as it did for probably find new phenomena, as it did for

optical diagnostics in 1997 optical diagnostics in 1997

1980'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 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

Heating requirements of Heating requirements of E3DE3D

Coherent Echo Coherent Echo resolutionsresolutions

Incoherent Scatter Incoherent Scatter resolutionsresolutions

RegionRegion HeighHeightt

timetime horizhoriz HeightHeight timetime Horiz*Horiz*

85 km85 km < < 100m100m

100m100mss

30m30m 1 km1 km 1-1-10s10s

1 km1 km

110 110 kmkm

100m 100m 10 ms10 ms 100100mm

1 km1 km 1s1s 10m*10m*

250 250 kmkm

100m100m 10 ms10 ms 100100mm

1-2 km1-2 km 1s1s 10m*10m*ThroughThroughInterferometryInterferometry * = perpendicular to B,* = perpendicular to B,

i.e. ca. 13i.e. ca. 13°tilt to south°tilt to south

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 within requiring volumetric imaging of the ionosphere within ±± ca. 15 ca. 15° ° of HF beam direction.of HF beam direction.

Strong (coherent) signals vary on 100’s m scale in altitude at >200 kmStrong (coherent) signals vary on 100’s m scale in altitude at >200 km

Cavitation spectra

decay linefirst cascade

second cascade

GYROHARMONIGYROHARMONICC

EffectsEffects

ca. 100 km N-S extentca. 100 km N-S extentcoherent backscatter, coherent backscatter, horizontal look. horizontal look.

Many F-region phenomena show a very Many F-region phenomena show a very strong dependence on the angle between strong dependence on the angle between the HF wave and the geomagnetic fieldthe HF wave and the geomagnetic field

For the E region (<200km) there has never been documented any such dependence.

Tokyo, 29-30 May 2007

Norway-Japan Symposium onPolar, Space, and Climate Research

© EISCAT Scientific Association Tony van Eyken

ElectroElectron n

heating heating and and UHF UHF

beam beam swinginswingin

gg7 Oct 1999

4.954 MHz

ERP = 100 MW

O-mode

(Rietveld et al., JGR,

2003)

Where should the E3D core be situated ?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-alignedTo measure field-aligned

200-300 km

If the core is built elsewhere, should If the core is built elsewhere, should we:we:

move Heating or build a new heater ?move Heating or build a new heater ?

One could move the 30-yr old transmitters One could move the 30-yr old transmitters but antennas and feeds need rebuilding.but antennas and feeds need rebuilding.

If so, will we have the money ?If so, will we have the money ?