2 The past G. Marconi (1874 -1937) Nobel Prize 1909 There had to be a reflecting layer in order to explain his trans-Atlantic radio wave connection.Reflecting layer at km altitude (the ionosphere)Radio SenderEarthReceiver
3 The past N. Tesla ( )Tesla developed high-frequency high-power generators
4 The pastAt the same time as Marconi, Tesla wanted to transmit energy as well as information using wireless radio waves.He built a transmission tower for this pupose.However, his work had little to do with modern ionospheric research.
5 Geometry of the Luxembourg effect The pastGeometry of the Luxembourg effect(Tellegen, 1933)
6 EISCAT consists of much more than just radars EISCAT consists of much more than just radars. It possesses the world‘s largest high-frequency (HF) ionospheric modifi-cation facility, called HEATING or simply the HEATER.Built by the Max-Planck-Society in the late 1970s, it passed to EISCAT in 1993.EISCAT mainland
7 A geographic overview of the EISCAT radar, HEATING & SPEAR HF facilities and CUTLASS coherent scatter radars
8 The Heating facility at Tromsø ControlAntenna 1TransmitterAntenna 2Antenna 3
16 Beam forming 2 Antennas give a broad beam 4 Antennas give a narrower beamwith more power in the forwarddirection and less power in allother directions.Effective Radiated Power = Radiated power Antenna gainAt Heating: 300 MW = 1.1 MW 270 for low gain antennas1.2 GW = 1200 MW = 1.1 MW for high gain antenna
18 A comparison HEATING SPEAR HAARP (final) Power (MW): 1.1 0.192 3.3 Antenna 24 and & Gain (dB):ERP (MW): 300 & &Freq. (MHZ): & &Polarisation: O & X O & X O & XBeam only north-south any any Steering: relatively slow fast fastDiagnostics: KST ESR ? CUTLASS CUTLASS KODIAK Dynasonde ? Digisonde
19 The ionosphere Fc = 8.98*sqrt(Ne) for O-mode Fc = 8.98*sqrt(Ne) + 0.5*Be/m for X-mode
20 A comparison of frequency range and effective radiated power of different facilities1GW100 MWSPEAR10 MW
21 Why do we need the HEATING facility? Why?: HF facilities are the only true active experiments in the ionosphere because the plasma may be temporarily modified under user control.Operations: ~200 hours per year (1 year=8760 hours), mostly in user-defined campaign mode.Experiments can be divided into 2 groups:Plasma physics investigations: the ionosphere is used as a laboratory to study wave-plasma turbulence and instabilities.Geophysical investigations: ionospheric, atmospheric or magnetospheric researchis undertaken.
22 The Incoherent Scatter Radar Spectra with Ion and Plasma lines corresponding to ion-acoustic waves and Langmuir wavesLangmuir turbulence, the parametric decay instability:e/m pump(0 ,0) Langmuir(0 - ia,-k) + IonAcoustic(ia ,k)Langmuir(0 - ia,-k) Langmuir(0 - 2ia,k) + IonAcoustic (ia,-2k)The component of the pump electric field parallel to the Earth's magnetic field is what matters.Thermal resonance instability:e/m pump + field-aligned electron density striation electrostatic wave (UH)Upper hybrid (UH) resonance condition: 02 = p2 + e2The component of the pump electric field perpendicular to the Earth's magnetic field is what matters.
23 PLASMA TURBULENCE 12 Nov 2001 5.423 MHz ERP = 830 MW O-mode UHF ion line spectraHF onHF off
28 StriationsAmplitude of radio waves received from the satellite
29 StriationsAfter HF pumpoff, theirregularitiesdecay with time
30 HF induced E-region STARE backscatter (144 MHz)Tromsø
31 Artificially raised electron temperatures 16 Feb 19994.04 MHzERP = 75 MWO-modeHeater on
32 HF pump-induced artificial optical emissions 16 Feb MHz ERP = 75 MW O-mode17:40 HF on17:44 HF off
33 HEATER and UHF beam swinging UHF zenith angle7 Oct 19994.954 MHzERP = 100 MWO-mode
34 shifted onto magnetic field line ARTIFICIAL AURORAshifted onto magnetic field lineHeater beam(vertical)Spitze directionField aligned21 Feb 1999630 nmStart time:UTStep=480 sec4.04 MHzERP = 75 MWO-mode
36 Stimulated Electromagnetic Emissions are weak radio waves produced in the ionosphere by HF pumping. They were originally discovered at HEATING.HF transmit frequencyGyroharmonic 1.38 MHz in F-layer
37 GYRO-HARMONICSpecial effects appear for HF frequencies close to an electron gyro-harmonic.(~1.38 MHz in F-layer)
39 VHFPMSEArtificial HF modulation of Polar Mesospheric Summer Echoes. VHF backscatter power reduces by >40 dB.10 July 19995.423 MHzERP = 630 MWX-modeHF offHF onNegatively charged aerosols, I.e. ice particles or cluster ions, prevent electron diffusion from equalising electron irregularity structures in the mesopshere, which cause strong coherent echoes, I.e. PMSE. Increasing electron temperature compensates the effect of negatively charged aerosols on the diffusion of electrons. Increasing Te enhances electron diffusion and destroys PMSE.
40 ULF ELF VLF waves Satellite in the magnetosphere Ionosphere DC current Conductivity modulation causes electrojet modulation, which acts as a huge natural antenna100 km altitude30 km diametersuperimposedac currentW ULF/ELF/VLF wavesare radiated from the ionosphereHeating Tx:0.2-1 GW HF wave is amplitude modulated and radiatedVLF receiver
41 Very Low Frequency waves (kHz) Natural (lightning) and artificial (HEATING) ducted VLF waves resonate with trapped particles in the magnetosphere causing pitch angle scattering and precipitation.
42 Ultra Low Frequency waves (3 Hz) Field line taggingFiled line tagging
43 Artificial Periodic Irregularities (API) The API technique was discovered at SURA and allows any HF pump and ionosonde to probe the ionosphere. API are formed by a standing wave due to interference between the upward radiated wave and its own reflection from the ionosphere.Measured parameters include: N(n), N(e), N(O-), vertical V(i), T(n), T(i) & T(e)
44 Further information EISCAT/HEATING www.eiscat.uit.no/heater.html HAARPHIPASARECIBOSURASPEAR