Electrodynamic mechanisms that limit the electron concentration in a laser spark

The joint evolution of the electromagnetic field and of the plasma in a nonequilibrium discharge produced in a gas by a focused laser beam is investigated. The maximum electron density in the breakdown wave N/sub e/ max, which is determined by the electrodynamic mechanisms that limit the electron avalanche (by refraction and absorption) is obtained. The value of N/sub e/ max is proportional to the square of the convergence angle of the beam and increases (logarithmically) with decrease in the initial (pre-breakdown) density