Your browser doesn't support javascript.
loading
Show: 20 | 50 | 100
Results 1 - 7 de 7
Filter
Add more filters










Database
Language
Publication year range
1.
Sci Rep ; 13(1): 18542, 2023 Oct 29.
Article in English | MEDLINE | ID: mdl-37899407

ABSTRACT

In the framework of the Laser Lightning Rod project, whose aim is to show that laser-induced filaments can guide lightning discharges over considerable distances, we study over a distance of 140 m the filaments created by a laser system with J-range pulses of 1 ps duration at 1 kHz repetition rate. We investigate the spatial evolution of the multiple filamentation regime using the fundamental beam at 1030 nm or using combination with the second and third harmonics. The measurements were made using both a collimated beam and a loosely focused beam.

2.
Nat Photonics ; 17(3): 231-235, 2023.
Article in English | MEDLINE | ID: mdl-36909208

ABSTRACT

Lightning discharges between charged clouds and the Earth's surface are responsible for considerable damages and casualties. It is therefore important to develop better protection methods in addition to the traditional Franklin rod. Here we present the first demonstration that laser-induced filaments-formed in the sky by short and intense laser pulses-can guide lightning discharges over considerable distances. We believe that this experimental breakthrough will lead to progress in lightning protection and lightning physics. An experimental campaign was conducted on the Säntis mountain in north-eastern Switzerland during the summer of 2021 with a high-repetition-rate terawatt laser. The guiding of an upward negative lightning leader over a distance of 50 m was recorded by two separate high-speed cameras. The guiding of negative lightning leaders by laser filaments was corroborated in three other instances by very-high-frequency interferometric measurements, and the number of X-ray bursts detected during guided lightning events greatly increased. Although this research field has been very active for more than 20 years, this is the first field-result that experimentally demonstrates lightning guided by lasers. This work paves the way for new atmospheric applications of ultrashort lasers and represents an important step forward in the development of a laser based lightning protection for airports, launchpads or large infrastructures.

3.
Opt Express ; 27(8): 11339-11347, 2019 Apr 15.
Article in English | MEDLINE | ID: mdl-31052979

ABSTRACT

We study the use of frequency upconversion schemes of near-IR picosecond laser pulses and compare their ability to guide and trigger electric discharges through filamentation in air. Upconversion, such as Second Harmonic Generation, is favorable for triggering electric discharges for given amount of available laser energy, even taking into account the losses inherent to frequency conversion. We focus on the practical question of optimizing the use of energy from a given available laser system and the potential advantage to use frequency conversion schemes.

4.
Phys Rev E ; 93(6): 063106, 2016 Jun.
Article in English | MEDLINE | ID: mdl-27415357

ABSTRACT

Acoustic signals generated by filamentation of ultrashort terawatt laser pulses in water are characterized experimentally. Measurements reveal a strong influence of input pulse duration on the shape and intensity of the acoustic wave. Numerical simulations of the laser pulse nonlinear propagation and the subsequent water hydrodynamics and acoustic wave generation show that the strong acoustic emission is related to the mechanism of superfilamention in water. The elongated shape of the plasma volume where energy is deposited drives the far-field profile of the acoustic signal, which takes the form of a radially directed pressure wave with a single oscillation and a very broad spectrum.

5.
J Acoust Soc Am ; 137(4): EL288-92, 2015 Apr.
Article in English | MEDLINE | ID: mdl-25920879

ABSTRACT

Acoustic signals generated in water by terawatt (TW) laser pulses undergoing filamentation are studied. The acoustic signal has a very broad spectrum, spanning from 0.1 to 10 MHz and is confined in the plane perpendicular to the laser direction. Such a source appears to be promising for the development of remote laser based acoustic applications.

6.
Opt Express ; 17(14): 11450-6, 2009 Jul 06.
Article in English | MEDLINE | ID: mdl-19582060

ABSTRACT

Short lived plasma channels generated through filamentation of femtosecond laser pulses in air can be revived after several milliseconds by a delayed nanosecond pulse. Electrons initially ionized from oxygen molecules and subsequently captured by neutral oxygen molecules provide the long-lived reservoir of low affinity allowing this process. A Bessel-like nanosecond-duration laser beam can easily detach these weakly bound electrons and multiply them in an avalanche process. We have experimentally demonstrated such revivals over a channel length of 50 cm by focusing the nanosecond laser with an axicon.


Subject(s)
Lasers , Optics and Photonics , Air , Electrons , Equipment Design , Oxygen/chemistry , Time Factors
7.
Opt Express ; 16(8): 5757-63, 2008 Apr 14.
Article in English | MEDLINE | ID: mdl-18542684

ABSTRACT

We investigated the possibility to trigger real-scale lightning using ionized filaments generated by ultrashort laser pulses in the atmosphere. Under conditions of high electric field during two thunderstorms, we observed a statistically significant number of electric events synchronized with the laser pulses, at the location of the filaments. This observation suggests that corona discharges may have been triggered by filaments.


Subject(s)
Atmosphere , Ecosystem , Hot Temperature , Lasers , Lightning , Models, Theoretical , Computer Simulation
SELECTION OF CITATIONS
SEARCH DETAIL
...