The influence of electron density on the formation of streamers in electrical discharges triggered with ultrashort laser pulses

In an ongoing program using ultrashort laser pulses to provoke discharges in air over considerable distances at electric fields below breakdown threshold, we have studied the conditions for the onset of streamers in such laser-produced plasmas, both experimentally and through numerical simulations. The results demonstrate the importance of the electron density and of its gradient on the generation of streamers. Also, a significant reduction of the breakdown voltage for a 30 cm plane-plane gap in air was observed with a laser pulse energy of 15 mJ. Finally, a direct comparison of laser-induced breakdown in air and in nitrogen shows the influence of electron attachment to oxygen on the discharge process.

[1]  F. Bastien,et al.  A model of the streamer‐induced spark formation based on neutral dynamics , 1979 .

[2]  Wu,et al.  Formation and propagation of streamers in N2 and N2-SF6 mixtures. , 1988, Physical review. A, General physics.

[3]  Diana Anderson,et al.  Variational approach to nonlinear self‐focusing of Gaussian laser beams , 1977 .

[4]  A. Kulikovsky.  Positive streamer between parallel plate electrodes in atmospheric pressure air , 1997 .

[5]  Bernard Prade,et al.  Determination of the inertial contribution to the nonlinear refractive index of air, N 2 , and O 2 by use of unfocused high-intensity femtosecond laser pulses , 1997 .

[6]  Jean-Claude Kieffer,et al.  Filamentation of ultrashort pulse laser beams resulting from their propagation over long distances in air , 1999 .

[7]  E. Marode,et al.  The mechanism of spark breakdown in air at atmospheric pressure between a positive point and a plane. I. Experimental: Nature of the streamer track , 1975 .

[8]  C. Max.  Strong self‐focusing due to the ponderomotive force in plasmas , 1976 .

[9]  A. Guenther,et al.  Laser-triggered megavolt switching , 1967 .

[10]  H. Mercure,et al.  A laser-triggered spark gap for 750 kV, 20 ns risetime impulse generator , 1989 .

[11]  J. Diels,et al.  Femtosecond ultraviolet laser pulse induced lightning discharges in gases , 1995 .

[12]  Takatoshi Shindo,et al.  Model experiments of laser-triggered lightning , 1993 .

[13]  Takatoshi Shindo,et al.  Development of long gap discharges guided by a pulsed CO2 laser , 1993 .

[14]  Keiji Nakamura,et al.  Fundamental research on lightning triggering by means of UV lasers , 1994 .

[15]  G. W. Penney,et al.  Photoionization Measurements in Air, Oxygen, and Nitrogen , 1970 .

[16]  A. Kulikovsky.  The mechanism of positive streamer acceleration and expansion in air in a strong external field , 1997 .

[17]  L. M. Ball.  The laser lightning rod system: thunderstorm domestication. , 1974, Applied optics.

[18]  M. Miki,et al.  Guiding of electrical discharges under atmospheric air by ultraviolet laser‐produced plasma channel , 1996 .

[19]  Tomoo Ushio,et al.  A possible way to trigger lightning using a laser , 1995 .

[20]  Yaochun Shen.  Principles of nonlinear optics , 1984 .

[21]  L. Keldysh,et al.  IONIZATION IN THE FIELD OF A STRONG ELECTROMAGNETIC WAVE , 1964 .

[22]  Y. Moriyoshi,et al.  Transition of the apparent activation energy for the growth of boron films as a function of substrate temperature in plasma-enhanced chemical vapour deposition from B2H6+He , 1990 .

[23]  Elaine S. Oran,et al.  LCPFCT-A Flux-Corrected Transport Algorithm for Solving Generalized Continuity Equations , 1993 .

[24]  A. Guenther,et al.  Investigation of a Laser Triggered Spark Gap , 1965 .

[25]  A. Guenther,et al.  12.2 - Laser-triggered megavolt switching , 1967 .

[26]  D. Koopman,et al.  Channeling of an Ionizing Electrical Streamer by a Laser Beam , 1971 .

[27]  Iu. P. Raizer.  Gas Discharge Physics , 1991 .

[28]  J. Diels,et al.  Use of self-trapped filaments in air to trigger lightning , 1994, Ultrafast Phenomena.

[29]  Esarey,et al.  Self-guiding and stability of intense optical beams in gases undergoing ionization. , 1996, Physical review. E, Statistical physics, plasmas, fluids, and related interdisciplinary topics.