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Laser Protection Against Lightning

#0956


Laser Spark for Atmospheric Electricity Guidance

Tech Area / Field

  • PHY-OPL/Optics and Lasers/Physics

Status
3 Approved without Funding

Registration date
16.04.1997

Leading Institute
Vavilov State Optical Institute (GOI) / Research Institute for Complex Testing of Optical Devices, Russia, Leningrad reg., Sosnovy Bor

Supporting institutes

  • St Petersburg State Polytechnical University, Russia, St Petersburg

Project summary

International Electrotechnical Commission (IEC) developed the international standard of requirements for lightning protection system application (CEI/IEC 1024-1:1990) in 1990, which noted that such installations as power supply lines, electronic communication lines, large-sized vehicles, and environmentally dangerous installations were in need the protection system of high reliability. The laser lightning protection system based on lightning stroke triggering and arresting by long laser spark (LLS) generation is the system needed. Such advantages of the laser method as high speed of response, ability of remote generation of a spark near a thundercloud, feasibility of repeated work, large operation range allow to predict high protection reliability, which is not rigorously analogous to currently used techniques.

The project goal is to develop of conceptual design of laser lightning protection systems (LPS) based on the atmospheric electric discharges control by long laser spark.

LPS comprises the following units: thunderstorm monitoring equipment, laser source, optical forming system controlling the output laser beam, and lightning receiver. Two modes of LPS operation are examined in the project. In the first one (triggering mode), ripening cell of thundercloud is forced discharged by LLS generated near the thundercloud moving to installation. The lightning stroke is guided to the earth or to lightning receivers installed around the protected object at safe distance. At the second mode of the system operation (lightning arresting mode), when lightning struck conditions around the installation are monitored continuously, long laser spark is generated closely to lightning receiver top within the time interval between lightning leader appearance instant and its time instant of orientation to installation protected.

The possibility of the use of LLS to control an orientation of discharges in long air gaps was demonstrated by own test experiments carried out in SPSTU as early as in 70-th [1]. Later the experimental data and theoretical results showed that the forced discharge of thunderclouds could be initiated if LLS of 100 m long at the needed spark spatial density could be generated near the thunderclouds. To generate the spark the output energy of 1 kJ in a pulse have to be achieved without reference to beam damage effects caused by atmospheric turbulence and precipitation, that is, the spark could be brought off by state-of-the-art lasers.

The key problems defining the creation feasibility of the laser lightning protection system are the following:


- determination of critical electric-physical LLS characteristics affecting lightning triggering and orientation along the LLS track,
- development of methods for the remote LLS generation in real atmosphere,
- development of atmosphere electric field measurement techniques to control LPS.

To solve the project problems, for example, SPSTU has the unique high voltage facility at own disposal, namely: generator of voltage impulses of 7 MV at stored energy up to 560kJ, two cascade testing transformer with outlet voltage of 3 MV, and special designed test area which allows to carry out the experiments on discharge guidance in air gaps of 30 m long. These facility is supposed to be used to carry out study on LLS and inhomogeneous electric field interaction, to test critical LLS parameters affecting discharge guidance, as well as to develop atmosphere electrical field measurement techniques and to make experiments on discharge orientation along spark track.

There is repetitively pulsed CO2 laser with output power of 40 kW in RICT to investigate high power laser radiation propagation through atmosphere. The laser radiation can be directed to real atmosphere range of 3 km long. The atmosphere range is equipped by recording set up to measure both radiation characteristics and meteorological parameters, namely: aerosol components of atmosphere, atmospheric turbulence value, humidity and so on. This facility is supposed to be used to study on output laser radiation characteristic optimization, development of methods of laser radiation control, development optical forming systems making laser beam characteristics available for remote LLS generation up to distance of 1 km. In these researches, the results of investigation of high power laser radiation propagation through real atmosphere range [2] and laser beam control techniques developed [3] will be used.

These investigations will allow making LPS conceptual design, to develop main principals of the system construction, to determine the system's efficiency.

Choice of CO2 laser as a laser source is explained by lower thresholds of optical air break-down as compared with the thresholds by Nd-laser, its capability to operate in repetitively-pulsed mode, as well as low laser beam distortion dependencies on atmosphere turbulence and opportunity to use its radiation for «brightening» of atmospheric channel in spark generation region.

The equipment to be developed during the project implementation, namely - high power laser, forming optical systems, apparatus for atmospheric electrical field monitoring - will become the prototype for compact system to be comparable in price of the currently used protection systems.

The project-developed methods of LLS remote generation and effective radiation delivery through near-land atmosphere could be used in various fields of science and technology, particularly in laser system for destruction of atmospheric contamination, ecological monitoring, lidar systems, communication line systems in real atmosphere.

The BET Company and University of Paderborn (Germany) supported the presented project when the main project propositions have been discussed. They were interested in both possible scientific results and the protection system design to be developed.


1. G.D.Kadzov and et al, "Investigation of high-ionization channel influence created of power laser on the electrical discharge development in long air gap", J. of Tech. Phys. 47, is. 9 (1977), in Russian.
2. V.L.Okulov, Yu.A.Rezunkov, A.S.Saakjan et al. Measurement of CO2 laser radiation scattering in the atmosphere. // In «Laser Optics-95». Proceedings of SPIE, vol. 2773, p. 136.
3. A.A.Ageichik, S.A.Dimakov, D.A.Gorjachkin et al. Phase conjugation in a high-power E-beam-sustained CO2 laser. Proc. of SPIE, 1992, vol. 1841, pp. 181-189.


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