Abstract:International audienceThe guiding of meter scale electric discharges produced in air by a Tesla coil is realized in laboratory using a focused terawatt laser pulse undergoing filamentation. The influence of the focus position, the laser arrival time or the gap length is studied to determine the best conditions for efficient laser guiding. Discharge parameters such as delay, jitter and resistance are characterized. An increase of the discharge length by a factor 5 has been achieved with the laser filaments, cor… Show more
“…The synchronization between the laser pulse and the AC waveform was optimized for the maximum laser-guided discharge length (>95%) over the 200-cm air gap. This was achieved by matching the laser-generation of plasma filaments with one peak of the Tesla coil electric field89, which accelerates the laser-produced free electrons along the plasma channel.…”
Section: Methodsmentioning
confidence: 99%
“…These results on laser-guiding of pulsed direct current (DC) high-voltage demonstrated an increase of the discharge length relative to the natural breakdown gap by a factor of 1.3 to 1.5 only for long air gap36. On the other hand, recent results using pulsed Tesla coil sources showed more significant effect and the laser-guided discharge length was increased fourfold89. These works have mainly been motivated by triggering of lightning from storm clouds10 and to transport electric charges to a specific position.…”
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.
“…The synchronization between the laser pulse and the AC waveform was optimized for the maximum laser-guided discharge length (>95%) over the 200-cm air gap. This was achieved by matching the laser-generation of plasma filaments with one peak of the Tesla coil electric field89, which accelerates the laser-produced free electrons along the plasma channel.…”
Section: Methodsmentioning
confidence: 99%
“…These results on laser-guiding of pulsed direct current (DC) high-voltage demonstrated an increase of the discharge length relative to the natural breakdown gap by a factor of 1.3 to 1.5 only for long air gap36. On the other hand, recent results using pulsed Tesla coil sources showed more significant effect and the laser-guided discharge length was increased fourfold89. These works have mainly been motivated by triggering of lightning from storm clouds10 and to transport electric charges to a specific position.…”
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.
“…In order to extend the gap to 85 mm, like in the previous case, with a voltage as low as 28 kV, we make use of an axicon lens instead of a spherical lens to generate laser filaments, a technique which proved able to decrease the breakdown voltage of air by one order of magnitude 24 . This result represents an even higher increase in discharge length than was observed with AC high voltage (~400%) 41 , 42 . Figure 4 Long duration, low current guided discharges.…”
Section: Resultsmentioning
confidence: 61%
“…Therefore the lengthening of the discharge lifetime is an aspect that can be completely dissociated from the lengthening of the discharge gap. Indeed already exist methods based on filamentation-guided discharges that can be used to generate meter-long sparks using small-scale high-voltage sources 41 , 42 . Once a well-guided spark is generated, only the external circuit supplying current to the plasma can play a role in the discharge stabilization.…”
Laser filamentation offers a promising way for the remote handling of large electrical power in the form of guided arc discharges. We here report that it is possible to increase by several orders of magnitude the lifetime of straight plasma channels from filamentation-guided sparks in atmospheric air. A 30 ms lifetime can be reached using a low-intensity, 100 mA current pulse. Stability of the plasma shape is maintained over such a timescale through a continuous Joule heating from the current. This paves the way for applications based on the generation of straight, long duration plasma channels, like virtual plasma antennas or contactless transfer of electric energy.
“…Recently, there has been a renewed interest in the ability of Tesla transformers to produce long electrical discharges in air because these discharges can be guided by laser filaments. [2][3][4][5][6] To date, laser-guided discharges from Tesla transformers have achieved a greater enhancement in length than those from other, primarily direct-current supplies, 7 and additionally can be produced using only a single electrical terminal. 3 This makes Tesla transformers and similar supplies attractive for research towards the control of electrical discharges, 8 their interaction with laser filaments, 9 the generation of plasma antennas, 10 and the laser guiding of lightning.…”
A compact Marx generator was built to mimic a spark-gap Tesla transformer. The generator produced radio-frequency pulses of up to ±200 kV and ±15 A with a frequency between 110 and 280 kHz at a repetition rate of 120 Hz. The generator tolerated larger circuit-parameter perturbations than is expected for conventional Tesla transformers. Possible applications include research on the control and laser guiding of spark discharges.
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