Fundamentals and Applications of Plasma Filaments L. Wöste Fachbereich Physik der Freien Universität woeste@physik.fu-berlin.de Coworkers Cooperation partners K. Stelmaszczyk J.-P. Wolf P. Rohwetter J. Kasparian W. Nakaema, M. Rodriguez, H. Wille, R. Bourayou, H. Zuoquiang, T. Fujii, R. Sauerbrey, A. Mysyrowicz, W. Kalkner, G. Méchain, Y. Petit, S. Henin, J. Yu, E. Salmon, G. Méjean, Y.-B. André, L. Klingbeil, K. Rethmeier TheTeramobile Project was financed by CNRS, DFG and SNF
Fundamentals and Applications of Plasma Filaments Contents 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 femtosecond laser pulse in air or gas! An amazing, white-light emitting filament emerges! First time observed in thelab by: A.Braun, G.Korn, G.Mourou et al. Opt. Lett., 20(1995),73
How is the white light formed? E(t) Kerr: n = n 0 + n 2 I(x,t) E(t) ω Self-Phase Modulation ( ) ω n ω c 2 0 t = 0 z di ( t) dt
White-Light Continuum J.Kasparian et al., Opt. Lett. 25, 1397 (2000)
What is the filament formation mechanism? Kerr Lens n = n 0 + n 2 I(r) n 2 = 3 10-19 cm 2 /W in air Plasma Lens n = ρ ( I ) ρ ρ c = 2 10 21 cm -3 in air c radius wave front radius wave front Propagation Propagation Plasma Kerr Lens
Theoretical calculation Properties Φ = 100 µm L > 300 m n <> 10-5 E = 1-5 mj I = 10 14 W/cm 2 ρ = 10 15 cm -3 ρ n larger than thermal turbuleces -> almost no influence on propagation!
Properties of these filaments When pumping@ 800nm with4mj pulsesof60fs: d = 100 µm L ~ 100 m, I = 10 14 W/cm 2, ρ = 10 15 cm -3
and they are electrically conductive!
Testing the EURO:
An emerging industrial application:* Filament cut @ 6m distance * Patent No.:US 8,097,830 B2
Filament Cut
An emerging medical application: Bone and Filament cut @ 2m distance
Filament- induced breakdown spectroscopy (FIBS) on different metals
FIBS on different Minerals Future Objects - mineral analysis - industrial deposits - radioactive fallouts - ground humidity - plant stress detection But howfarcanwego?
Plasma-lines of copper observed at 100 meters distance
Optimizing the supercontinuum for remote FIBS (filament induced breakdown spectroscopy) Femtosecond laser Filament Screen Telescope PMT Filter wheel Signal Loop Genetic algorithm
First preliminary results Evolution graph
Observations suggest: Optimal pulse shape increases Supercontinuum intensity by up to ~20% compared to the optimum linear chirp. and now let us work at higher energies!
Mono-filamentation(<5 mj)
Multi- filamentation(>5 mj)
Autoguided propagation and multiple filamentation focussing Kerr lens de-focussing plasma lens: At higher energies (>5 mj): multiple filamentation
And now lets produce extended filament bundles to study the atmosphere Specs of our pump laser: 240mJ @ 60fs = 4 Terawatt 400 nm 800 nm Wavelenghth Careful: Since the spectral bandwidth of our filaments is rather broad, this has to be considered, when propagating over long distances!
Compensating Group-Velocity Dispersion no GVD compensation GVD fs pulse chirped pulse with GVD compensation GVD anti-chirped (precompensed) pulse fs pulse
Principle of the fs - Lidar Ultrashort Laser Timeresolved spectrometer Chirp control Telescope
The result: extended bundles of FILAMENTS!
The Teramobile: A mobile fs -TW Laser and LIDAR System
Laser Titane-Saphire H. Wille et al., Eur. Phys. J. - A.P., 20, 183 (2002) J. Kasparian et al., Science 301, 61 (2003) Performances : 790 nm 350 mj à 10 Hz 60 fs 5 TW
Tautenburg Observatorium
White Light until 18 km
Control of the white-light generation Positive chirp (600 fs) GVD precompensation (-600 fs)
Conical emission Slight pre-compensation of GVD (-150 fs) Ø Ø conical emission h = 1900 m
White-Light Continuum J.Kasparian et al., Opt. Lett. 25, 1397 (2000)
White-light atmospheric absorption spectrum from 4 km altitude 1.0 0.5 0.0 6800 6900 7000 7100 7200 7300 7400 1.0 0.5 O 2 0.0 7400 7500 7600 7700 7800 7900 8000 1.0 0.5 0.0 8000 8100 8200 8300 8400 8500 8600 1.0 0.5 H 2 O 0.0 8600 8700 8800 8900 9000 9100 9200
Simultaneous oxygen and water vapor measurement Transmission 1.2 normalized measurement Water vapor calculation Humidity 1.0 Water 0.8 0.6 0.4 0.2 0.0 814 815 816 817 Transmission 1.0 0.8 0.6 0.4 0.2 normalized measurement calculation Temperature Oxygen 0.0 761 762 763 764 765 Wavelength /nm RELATIVE humidity
22:0 0 Time evolution of the Ozone profile 22:3 0 23:0 0 23:3 0 00:0 0 00:3 0 01:0 0 01:3 0 02:0 0 03:0 0 05:3 0 06:0 0 06:3 0 07:3 0 Ozone (µg/m 3 ) Lyon, 29-30/07/02
Angular What distribution the origin measurement of the of intensty the white-light of the observed emitted return from a signals filament?
Backward enhancement of the white light emission Intensity (a.u.) 172 174 176 178 180 178 176 174 172 s_pol non linear 2001 linear 2001 Angle ( ) threshold at 178 p_pol 180 160 140 120 100 80 60 40 20 0 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 water reservoir heater fs-source: 800 nm, 100 fs, 220 mj cooler
Optimization of droplet formation in th fog chambee
Laser-produced Condensation
Condensation mechanism with strong Laserlight Laser +
Test in the real atmosphere: The pump&probe LIDAR Fiber bundle Laser Filaments Firing sequence Δt = 1 ms T = 200 ms time Optical detection Data Acquisition Telescope Ref. PD LIDAR transmitter: 532nm, 5 mj, 7 ns, 10 Hz Teramobile: 800nm, 220 mj, 120 fs, 5 Hz PC
Appearance of filament-formed droplets The pump&probe LIDAR Laser filaments Fiber bundle Optical detection Data Acquisition Telescope Ref. PD LIDAR transmitter: 532nm, 5 mj, 7 ns, 10 Hz PC Teramobile: 800nm, 220 mj, 120 fs, 5 Hz @ RH~70%!
Let s get back to him! Mark Twain (1835-1910): «Everyone talks about the weather, but no one tries to do something about it!»
After thehailstorm!.what can be done?
Hailflyers
Condensation mechanism with Ag + I - - + Do we want to contaminate our atmosphere wit expensive AgI?
Weather control Chinese bureau for weather control 北京市人工影响天气办公室 - 37 000 employees - 7000 rocket lounge bases - 210 km 3 rain produced (claim) - 1/8 increase of rain (claim)
How about lightnings?
Who is threatened by lightnings? Andwhatcanbedone?
he had the first idea!
A more modern solution : employing rockets
We want to prevent this!
Remember: Filaments are electrically conductive! let s test them!
Laser guiding setup 0 to 2 MV Ground (plane electrode, Ø 3 m) Adjustable focus HV electrode (sphere, Ø 12 cm) Contact Ionized filaments 0,5-4 m
Laser-control of high-voltage discharges 3 m
1 MVolt 0.7 MVolt without filament with filament
V oltag ge (kv ) 2000 1500 1000 500 Discharge triggering U 50 with laser U 50 without laser Lowest LIB voltage observed 0 0,0 0,5 1,0 1,5 2,0 2,5 3,0 3,5 4,0 Distance beween electrodes (m) M. Rodriguez et al., Opt. Lett. 27, 772 (2002)
Filament-Triggered Discharges in Rain Wetting the Discharge Gap in Rain
Filament-induced Discharge in Rain Probability reduced by 50 % Same threshold!
Field campaign Langmuir laboratory, New Mexico Tech Altitude 3200 m Metallic hall: Faraday cage for Teramobile
Experimental Setup E-field? RF filaments RF RF
Lightning Strikes RF detectors(lma) 100 % Laser and filament Let us look for pulse-synchronized strikes! Storm on Sept. 24/04 Strong E-Field 0 %
Laser-controlled lightning strikes der Luftfahrt Detectors Laser 100 % Laser induced lightning strikes! 98 % J. Kasparian et al., Optics Express 16, 5757 (2008)
The future of lightning control + + + + + + + Laser
Thank You! TotheTeam MatthieuLalanne FalkoSchwaneberg AlbrechtLindinger OliverGause JörgWichmann HaoZuoquiang LW GeorgAchazi FabianWeise MonikaPawlowska FranzHagemann PhilipRohwetter TorstenSiebert AndreaMerli WaltherNakaema CristinaKaposta BrigitteOdeh ThomasGelot KamilStelmaszczyk AndtoourcooperationPartners: Jean-PierreWolf JeromeKasparian