Fundamentals and Applications of

Plasma Filaments

L. Wöste

Fachbereich Physik der Freien Universität

woeste@physik.fu-berlin.dewoeste@physik.fu-berlin.de

Coworkers Cooperation partnersK. Stelmaszczyk J.-P. WolfP. Rohwetter J. Kasparian

W. Nakaema, M. Rodriguez, M. Rodriguez, H. H. WilleWille, , R. R. BourayouBourayou,, H. Zuoquiang, T. Fujii,R. Sauerbrey, A. Mysyrowicz, W. W. KalknerKalkner, , GG.. MéchainMéchain, Y. Petit, S. Henin, , Y. Petit, S. Henin, J. Yu, E. Salmon, G. Méjean, Y.Y.--B. André,B. André, L. Klingbeil, K. L. Klingbeil, K. RethmeierRethmeier

TheTeramobile Project was financed by CNRS, DFG and SNF

Fundamentals and Applications of

Plasma Filaments

Contents

− Formation of white light filaments− Formation of white light filaments− Properties and applications− Remote sensing of solid targets− Single and multiple filaments− White light analysis of the atmosphere− Filament-induced water condensation− Filament-based discharge control− Perspectives of lightning protection

Let‘ s propagate a millijoule femtosecondlaser pulse in air or gas!

First time observed in the lab by:

A.Braun, G.Korn, G.Mourou et al. Opt. Lett., 20(1995),73

An amazing, white-light emitting filament emerges!

E(t)Kerr:

n = n0 + n2 I(x,t)

How is the white light formed ?

E(t)( ) ( )

dt

tdIz

c

nt 02

0

ωωω −=

Self-Phase Modulation

White-Light Continuum

J.Kasparian et al., Opt. Lett. 25, 1397 (2000)

wavefront

n = n0 + n2I(r)

n2 = 3 10-19 cm2/W in air

rad

ius

ρc = 2 1021cm-3 in air

wavefront

rad

ius

Kerr Lens Plasma Lens

What is the filament formation mechanism?

c

In

ρρ )(−=∆

PropagationPropagation

Kerr Lens

Plasma

PropertiesΦ = 100 µm

L > 300 m∆n <> 10-5

Theoretical calculation

…∆n larger than thermal turbuleces -> almost no influence on propagation !

∆n <> 10-5

E = 1-5 mJI = 1014 W/cm2

ρ = 1015 cm-3

ρρρρ

Properties of these filaments

d = 100 µmL ~ 100 m, I = 1014 W/cm2,ρ = 1015 cm-3

When pumping @ 800nm

with 4mJ pulses of 60fs:

…and they areelectrically conductive!

Testing the EURO:

An emerging industrial application:*

Filament cut @ 6m distance

* Patent * Patent No.:USNo.:US 8,097,830 B28,097,830 B2

Filament Cut

An emerging medical application:

Filament cut @ 2m distanceBone and

Filament- induced breakdown spectroscopy (FIBS) on different metals

FIBS on different Minerals Future Objects

- industrial deposits

- radioactive fallouts

- mineral analysis

- radioactive fallouts

- ground humidity

- plant stress detection

But how far can we go?

Plasma-lines of copper observed at 100 meters distance

Femtosecond laser

Filament

Screen

Optimizing the supercontinuum for remote FIBS(filament induced breakdown spectroscopy)

Filament

Filterwheel

Telescope

PMT

„Signal“Genetic

algorithm

„Loop“

First preliminary results

Evolution graph

„Optimal pulse shape“ increases Supercontinuum intensity by up to

~20% compared to the optimum linear chirp.

Observations suggest:

… and now let us work at higher energies !

Mono-filamentation(<5 mJ)

Multi-filamentation(>5 mJ)

de-focussing plasma lens:

focussingKerr lens

Autoguided propagation

and multiple filamentation

At higher energies (>5 mJ): multiple filamentation

Specs of our pump laser: 240mJ @ 60fs = 4 Terawatt

And now lets produce extended filament bundles to study the atmosphere

•

Careful: Since the spectral bandwidthof our filaments is rather broad, this has to be considered,

when propagating over long distances !

400 nm 800 nmWavelenghth

fs pulse chirpedpulse

GVDno GVDcompensation

Group-Velocity Dispersion

Compensating

fs pulseanti-chirped (precompensed)

pulse

pulse

GVDwith GVDcompensation

Principle of the fs - Lidar

Chirp control

Ultrashort

Laser

Time-resolved

spectrometer

Telescope

The result:extended bundles of

FILAMENTS !

The Teramobile:A mobile fs -TW Laser and LIDAR System

Laser Titane-Saphire

Performances : 790 nm350 mJ à 10 Hz

60 fs5 TW

H. Wille et al., Eur. Phys. J. - A.P., 20, 183 (2002)J. Kasparian et al., Science 301, 61 (2003)

Tautenburg Observatorium

White Lightuntil

18 km

Positive chirp (600 fs) GVD precompensation (-600 fs)

Control of the white-light generation

Conical emission

Slight pre-compensation of GVD (-150 fs)

Ø

Ø

conical emissionh = 1900 m

White-Light Continuum

J.Kasparian et al., Opt. Lett. 25, 1397 (2000)

0.0

0.5

1.0

6800 6900 7000 7100 7200 7300 74000.0

0.5

1.0

White-light atmospheric absorption spectrum from 4 km altitude

O2

8600 8700 8800 8900 9000 9100 92000.0

0.5

1.0

8000 8100 8200 8300 8400 8500 86000.0

0.5

1.0

7400 7500 7600 7700 7800 7900 80000.0

H2O

Simultaneous oxygen and water vapor measurement

814 815 816 8170.0

0.2

0.4

0.6

0.8

1.0

1.2

Water vapor

Tra

nsm

issi

on

normalized measurement calculation

Water�Humidity

761 762 763 764 7650.0

0.2

0.4

0.6

0.8

1.0

814 815 816 817

Oxygen

Tra

nsm

issi

on

Wavelength /nm

normalized measurement calculation �Temperature

� RELATIVE humidity

Time evolution of the Ozone profile22:0

022:3

023:0

023:3

000:0

000:3

001:0

0

01:30

02:00

03:00

05:30

06:00

06:30

07:30

Ozone (µg/m3) Lyon, 29-30/07/02

What is the origin of theintensty of the observed return signals ?

Angular distribution measurementof the white-light emitted from a filament

120140160180

180 178178 176176174172 174 172

non linear 2001 linear 2001

Inte

nsi

ty (

a.u

.)

Backward enhancement of the white light emission

020406080100

threshold at 178

p_pols_polInte

nsi

ty (

a.u

.)

Angle (°)

J.Yu et al, Opt. Lett. 26(8), 533-535 (2001)

Filament-induced Condensation

P. Rohwetter et al., Nature Photonics, DOI 10.1038/NPHOTON.2010.115

Diffusion cloud chamber

fs-source:

heater

water reservoir

fs-source:800 nm, 100 fs,220 mJ

cooler

Optimization of droplet formationin th fog chambee

Laser-produced Condensation

Condensation mechanism with strong Laserlight

+

Laser

+

Fiber bundle

Laser

Filaments

Firing sequence

…

…

Δt = 1 ms T = 200 ms

Test in the real atmosphere:

The pump&probe LIDAR

Teramobile:

800nm, 220 mJ,

120 fs, 5 Hz

LIDAR transmitter:

532nm, 5 mJ, 7 ns, 10 Hz

Optical

detection

Data

Acquisition

PC

Telescope

Ref. PD

Fiber bundletime

Fiber bundle

Laser

filaments

The pump&probe LIDAR

Appearance of filament-formed droplets

Teramobile:

800nm, 220 mJ,

120 fs, 5 Hz

LIDAR transmitter:

532nm, 5 mJ, 7 ns, 10 Hz

Optical

detection

Data

Acquisition

PC

Telescope

Ref. PD

Fiber bundle

@ RH~70%!

Mark Twain (1835-1910):

« Everyone talks about the

Let´s get back to him!

« Everyone talks about the weather, but no one triesto do something about it! »

After the hail storm !

….what can be done?

Hail flyers

with Ag+I-

-

Condensation mechanism

+-

Do we want to contaminate our atmosphere wit expensiveAgI ?

Chinese bureau for weather control

Weather control

北京市人工影响天气办公室

- 37 000 employees

- 7000 rocket lounge bases

- 210 km3 rain produced (claim)

- 1/8 increase of rain (claim)

How about lightnings?

Who is threatened by lightnings?

And what can be done?

…he had the first idea!

employingrockets

A moremodernsolution :

We want to prevent this!

Remember: Filaments areelectrically conductive!

…let´s test them !

Laser guiding setup0 to —2 MV

Ground (plane electrode,Ø 3 m)

Adjustable focus

HV electrode(sphere, Ø 12 cm)

Ionized filaments

Adjustable focus

0,5 - 4 m

Contact

Laser-control of high-voltage discharges

3 m

1 MVolt 0.7 MVolt

without filament with filament

1000

1500

2000

U50

with laser U

50 without laser

Lowest LIB voltage observed

Vo

ltag

e (

kV)

Discharge triggering

0,0 0,5 1,0 1,5 2,0 2,5 3,0 3,5 4,00

500

1000

Vo

ltag

e (

kV)

D istance beween electrodes (m)

M. Rodriguez et al., Opt. Lett. 27, 772 (2002)

Filament-Triggered Discharges in RainWetting the Discharge Gap

in Rain

Filament-induced Discharge in Rain

Probability reduced by 50 %Same threshold !

Field campaignLangmuir laboratory,New Mexico TechAltitude 3200 m

Metallic hall:Faraday cage for TeramobileFaraday cage for Teramobile

Experimental Setup

filaments

E-field ?RF

RF filamentsRF

RF

Lightning Strikes

RF detectors(LMA)

Laser and filament

100 %

0 %Storm on Sept. 24/04Strong E-Field

Let us look for pulse-synchronized strikes!

Laser-controlled lightning strikes

Detectors

Laser

100 %

der Luftfahrt

98 %

Laser–inducedlightning strikes!

J. Kasparian et al., Optics Express 16, 5757 (2008)

der Luftfahrt

The future ofThe future of

lightninglightning controlcontrol

Laser

+ ++ ++

++

Laser

Thank You ! Thank You ! Thank You ! Thank You ! To the Team

MonikaPawlowska FranzHagemann PhilipRohwetter TorstenSiebert

HaoZuoquiang LW GeorgAchazi FabianWeise

MatthieuLalanne FalkoSchwaneberg AlbrechtLindinger OliverGause JörgWichmann

AndreaMerli WaltherNakaema CristinaKaposta BrigitteOdeh ThomasGelot KamilStelmaszczyk

And to our cooperation Partners:

Jean-PierreWolf JeromeKasparian