Transcript Heating overview

HEATING
expands the mind
EISCAT training course
1
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 100-200 km altitude (the ionosphere)
Radio Sender
Earth
2
Receiver
The past
N. Tesla (1856-1943)
Tesla
developed
high-frequency
high-power
generators
3
The past
At 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.
4
The past
Geometry of
the
Luxembourg
effect
(Tellegen, 1933)
5
EISCAT
mainland
EISCAT consists of
much more than just
radars. It possesses
the world‘s largest
high-frequency (HF)
ionospheric
modification facility, called
HEATING or simply
the HEATER.
Built by the MaxPlanck-Society in the
late 1970s, it passed to
EISCAT in 1993.
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A geographic overview of the EISCAT radar, HEATING &
SPEAR HF facilities and CUTLASS coherent scatter radars
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The Heating facility at Tromsø
Control
Antenna 1
Transmitter
Antenna 2
Antenna 3
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Tromsø HEATING facility layout
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HEATER control house with EISCAT radars in the background
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A single HEATING antenna
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An antenna array
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Transmitters
during construction: 6 of 12
13
Coax
Only 50 km of home-made
aluminium RF coaxial transmission
lines with mechanical switches
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Thermal expansion: One of many detours
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2 Antennas give
a broad beam
Beam forming
4 Antennas give a narrower beam
with more power in the forward
direction and less power in all
other directions.
Effective Radiated Power = Radiated power  Antenna gain
At Heating: 300 MW = 1.1 MW  270 for low gain antennas
1.2 GW = 1200 MW = 1.1 MW  1100 for high gain antenna
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•1970: Platteville, Colorado
•1975: SURA (Nizhni Novgorod), Russia
•~1980: Arecibo (Puerto Rico),
Tromsø (Norway), HIPAS (Alaska)
•1995: HAARP (Alaska)
•2003: SPEAR (Svalbard)
World
overview
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A comparison
HEATING
SPEAR
HAARP (final)
Power (MW): 1.1
0.192
3.3
Antenna
Gain (dB):
16 & 22
30
ERP (MW): 300 & 1200
7.6 & 30
3600
Freq. (MHZ): 3.9-5.4 & 5.4-8
2-3 & 4-6
2.8-10
Polarisation: O & X
O&X
O&X
Beam
Steering:
any
fast
any
fast
ESR
CUTLASS
?
?
KODIAK
Digisonde
24 and 30
only north-south
relatively slow
Diagnostics: KST
CUTLASS
Dynasonde
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The ionosphere
Fc = 8.98*sqrt(Ne) for O-mode
Fc = 8.98*sqrt(Ne) + 0.5*Be/m for X-mode
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A comparison of frequency range and effective
radiated power of different facilities
1GW
100 MW
SPEAR
10 MW
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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 research
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is undertaken.
The Incoherent Scatter Radar Spectra with Ion and Plasma lines
corresponding to ion-acoustic waves and Langmuir waves
Langmuir turbulence, the parametric decay
instability:
e/m pump(0 ,0)  Langmuir(0 - ia,-k) +
IonAcoustic(ia ,k)
Langmuir(0 - ia,-k)  Langmuir(0 - 2ia,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 + e2
The component of the pump electric field perpendicular to the Earth's magnetic field is
what matters.
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PLASMA TURBULENCE
12 Nov 2001 5.423 MHz ERP = 830 MW O-mode
UHF
ion line
spectra
HF on
HF off
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PLASMA TURBULENCE
The UHF
radar observes
HF pumpinduced
plasma
turbulence
5.423 MHz
ERP = 1.1 GW
O-mode
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PLASMA TURBULENCE
Z-mode
penetration
of the
ionosphere
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HF pump-induced magnetic field-aligned electron density
irregularities (up to ~5%) causes coherent radar reflections and
anomalous absorption (by scattering) of probing signals.
Striations
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HF induced F-region CUTLASS radar backscatter
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Striations
Amplitude of radio waves
received from the satellite
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Striations
After HF pump
off, the
irregularities
decay with time
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HF induced E-region STARE backscatter
(144 MHz)
Tromsø
30
Artificially
raised
electron
temperatures
16 Feb 1999
4.04 MHz
ERP = 75 MW
O-mode
Heater on
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HF pump-induced artificial optical emissions
16 Feb 1999 4.04 MHz ERP = 75 MW O-mode
17:40 HF on
17:44 HF off
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HEATER
and UHF
beam
swinging
UHF zenith angle
7 Oct 1999
4.954 MHz
ERP = 100 MW
O-mode
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ARTIFICIAL AURORA
shifted onto magnetic field line
Heater beam
(vertical)
Spitze direction
Field aligned
21 Feb 1999
630 nm
Start time:
17.07.50 UT
Step=480 sec
4.04 MHz
ERP = 75 MW
O-mode
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SEE
35
Stimulated Electromagnetic Emissions
HF transmit
frequency
Gyroharmonic  1.38 MHz
in F-layer
are weak radio
waves produced
in the
ionosphere by
HF pumping.
They were
originally
discovered at
HEATING.
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GYROHARMONIC
Special effects appear
for HF frequencies
close to an electron
gyro-harmonic.
(~1.38 MHz in F-layer)
37
GYROHARMONIC
3 Nov 2000 ERP = 70 MW O-mode
UHF
Cutlass
Artificial aurora 630 nm
38
VHF
HF off
PMSE
Artificial HF modulation of
Polar Mesospheric Summer
Echoes. VHF backscatter power
reduces by >40 dB.
10 July 1999
HF on
5.423 MHz
ERP = 630 MW
X-mode
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Satellite in the magnetosphere
ULF ELF VLF
waves
DC current
100 km altitude superimposed
ac current
Ionosphere
Conductivity modulation causes
electrojet modulation, which acts
as a huge natural antenna
30 km diameter
Heating Tx:
0.2-1 GW HF wave
is amplitude
modulated and
radiated
0.001-1 W ULF/ELF/VLF waves
are radiated from the ionosphere
VLF receiver
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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.
41
Ultra Low Frequency waves (3 Hz)
Field line tagging
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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)
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Further information
EISCAT/HEATING www.eiscat.uit.no/heater.html
HAARP
www.haarp.alaska.edu
HIPAS
www.hipas.alaska.edu
ARECIBO
www.naic.edu
SURA
www.nirfi.sci-nnov.ru/english/index2e.html
SPEAR
www.ion.le.ac.uk/spear/
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