Ionospheric Modulation & Climate Geo-engineering

7/30/2019 Ionospheric Modulation & Climate Geo-engineering.

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Ionospheric modification and ELF/VLF

wave generation by HAARP

Nikolai G. Lehtinen and Umran S. Inan

STAR Lab, Stanford University

January 7, 2006


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Generation of ELF/VLF waves


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HAARP

After upgrade in March 2006:

180 crossed dipole antennas

3.6 MW power

~2 GW effective radiated HF power (2.8-10

MHz) (lightning has ~20 GW isotropic ERP)

High Frequency Active Auroral Research Program


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HAARP and other HF heating

facilities


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Important electron-molecule interaction

concept: Dynamic friction force

Inelastic processes:

Rotational,

vibrational,electronic level

excitations

Dissociative

losses

Ionization

(E/N)br=130 Td where 1 Td = 10-21 V-m2


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Kinetic Equation Solver

(modified ELENDIF)

Time-dependent solution forf(v,t) = f0(v,t) + cos f1(v,t)

(almost isotropic)

Physical processes inluded in ELENDIF: Quasistatic electric field

Elastic scattering on neutrals and ions

Inelastic and superelastic scattering

Electron-electron collisions

Attachment and ionization

Photon-electron processes

External source of electronsNew:

Non-static (harmonic) electric field

Geomagnetic field


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Importance of these processes

The quasistatic

approximation

used by ELENDIFrequires m>>

Geomagnetic field

is also important:

H~2 x 1 MHz

H

HAARP


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Analytical solution

Margenau distribution

where l=v/ m=(N m)-1=const

Druyvesteyn distribution =0


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Calculated electron distributions

Electron distributions for various RMS E/N

(in Td). f>0 corresponds to extaordinary

wave (fH=1 MHz, h=91 km)

Effectiveelectric field issmaller than in

DC case:

+ ordinary

- extraordinary


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Breakdown field

(used for the estimate of m,eff)

Breakdown occurs

when ion> att

The point ofbreakdown (shown

with ) shifts up in

oscillating field

f(v) at ionization

energy (~15 eV) is

most important

h = 91 km, extraordinary, fH=1 MHz

2

13 1 31

2 10

br br H

DC

E E

N N N s m

+


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HF wave propagation

Power flux (1D), including losses:

HF conductivity (ordinary/extaordinary)


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Calculated HF electric field

Normalized field,

E/Ebr is shown

For comparison,we show the

dynamic friction

function

The N2 vibrational

threshold or

breakdown field arenot exceeded for

current or

upgraded HAARPpower


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Is breakdown achievable at all?

The electric fieldcan be higher in anon-steady statecase

Electric breakdownfield with altitude: Decreases due to

thinningatmosphere

But, increases due

to oscillations andmagnetization.

2

13 1 3

12 10

br br H

DC

E E

N N N s m

+

Propagation with no absorption


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Temperature modification

(daytime, x mode)


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Comparison of Maxwellian and

non-Maxwellian approaches


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DC conductivity changes

(for electrojet current)


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Conductivity tensor (DC)

Conductivity changes due to modification of

electron distribution

Approximate formulas were used previously

Pedersen (transverse)

Hall (off-diagonal)

Parallel


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Conductivity modification

Pedersenconductivity isincreased

Parallelconductivity is

decreased

C d ti it f ti f E/N


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Conductivity as a function of E/N

(x-mode, h=80 km, f=0,3,7 MHz)

Solid line shows

conductivitymodifications byDC field

Black intervalsconnect theconductivitiesmodified by

maximumHAARP heatingbefore and afterupgrade

R l ti h f d ti it


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Relative change of conductivity

(E)/ (E=0)


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Electric current calculations

In most previous works, it is

assumed that the electrojet field

Eej=const => inaccurate at lowfrequencies (no account for the

accumulation of charge) We assume static current, i.e.


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3D stationary J

Vertical B

Ambient E is along x

Ambient current ismostly along y

Models with E=0 donot consider closing

side currents max J/J0~0.3 for this

case

C l l t d J/J f i


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Calculated J/J0 for various

frequencies

Range 70-130km

Modified region

radius ~10 kmbefore upgradeand ~5 km afterupgrade

Calculatedmaximumcurrent and its

modificationoccur at~109km


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Conclusions

Our model includes both: Non-Maxwellian electron distribution

Self-absorption

Maxwellian electron distribution models,which calculate Te, cannot account forthe nonlinear T

esaturation.

The non-Maxwellian model allows tocalculate processes for which high-energy

tail of the electron distribution isimportant, such as: optical emissions

breakdown processes.


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Work in progress

Electrojet current modulation in non-static case

ELF/VLF emission

ELF/VLF wave propagation along the

geomagnetic field line

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Ionospheric Modulation & Climate Geo-engineering