Decay of an electronic vortex of a collisionless shock wave as a possible mechanism of a "Coulomb explosion"

A new mechanism of a "Coulomb explosion," where ions are accelerated by the electric field separating charges at the magnetic Debye radius r(B)similar to B/4 pi en(e), is proposed on the basis of a nonquasineutral model of electronic vortices in a magnetic field. It is shown by means of numerical calculations that in the process of acceleration of the ions a collisionless shock wave, whose front has an effective width of the order of delta similar to r(B), determined by the breakdown of quasineutrality, is formed in a time of the order of omega(pi)(-1), where omega(pi) is the ion plasma frequency. The origin of such explosive dynamics is the formation of "holes" in the electron density at characteristic times of the order of omega(pe)(-1) (omega(pe) is the electronic plasma frequency) as a result of the generation of electronic vorticity by the Weibel instability of an electromagnetic wave. Calculations for a laser pulse with intensity J similar to 6 x 10(18) W/cm(2) show that the ions expand in the radial direction with velocities up to 3.5 x 10(8) cm/s. (C) 1999 American Institute of Physics. [S0021-3640(99)00722-7].