Laser-guided energetic discharges over large air gaps by electric-field enhanced plasma filaments

Abstract

Recent works on plasma channels produced during the propagation of ultrashort and intense laser pulses in air demonstrated the guiding of electric discharges along the laser path. However, the short plasma lifetime limits the length of the laser-guided discharge. In this paper, the conductivity and lifetime of long plasma channels produced by ultrashort laser pulses is enhanced efficiently over many orders of magnitude by the electric field of a hybrid AC-DC high-voltage source. The AC electric pulse from a Tesla coil allowed to stimulate and maintain the highly conductive channel during few milliseconds in order to guide a subsequent 500 times more energetic discharge from a 30-kV DC source. This DC discharge was laser-guided over an air gap length of two metres, which is more than two orders of magnitude longer than the expected natural discharge length. Long plasma channel induced by laser pulses and stimulated by an external high-voltage source opens the way for wireless and efficient transportation of energetic current pulses over long air gaps and potentially for guiding lightning.

Electrical and Acoustic Parameters of Wire-Guided Discharges in Water: Experimental Determination and Phenomenological Scaling

“…Thus, in the case of the transient processes of such duration or longer, it is possible to substitute the transient resistance with an effective (constant) spark plasma resistance. For example, a constant plasma resistance was used to describe the transient current oscillations observed for short, sub-micrometer and millimeter air gaps [23], and for long, hundreds of centimeters, air gaps [24]. As shown in [20], the calculated resistance at the end of the transient process obtained using (3) is very close to the experimentally-obtained resistance of the breakdown channel.…”

Nonlinear rovibrational polarization response of water vapor to ultrashort long-wave infrared pulses

“…The addition of water vapor clearly leads to a significant departure from a Kerr-like behavior. In particular, instead of a susceptibility increasing linearly with intensity there is a more complex behavior including a significantly reduced gradient at intermediate intensities around 10 16 W/m 2 , indicating a reduced self-focusing effect at these intensities.…”

“…This phenomenon has possible applications in longrange free-space optical communication, remote sensing [4,5], synthesis of ultrashort pulses by higher harmonics generation [6,7], and lightning guiding [8][9][10], to name but a few. The atmospheric transparency windows in the mid-wave infrared (MWIR) (3-5 μm) [11,12] and long-wave infrared (LWIR) (8-12 μm) [13,14] regimes are of particular interest.…”

Shockwave-assisted laser filament conductivity

“…However, the electric field before the lightning initiation is close to DC. In this regime, new behaviors like discharge suppression and remote spark-free unloading [24,25] or an increase of the plasma lifetime in a coupled AC-DC configuration [26,27] have been observed.…”