SPATIOTEMPORAL DYNAMICS OF THE RESONANTLY EXCITED RELATIVISTIC PLASMA-WAVE DRIVEN BY A CO2-LASER

The dynamics of a relativistic plasma wave (RPW) resonantly excited by a two frequency CO2 laser pulse and the effects of this wave on a co- propagating relativistic electron beam were studied through experiment s and supporting simulations. The amplitude of the RPW and its harmoni cs were resolved in time and space with a Thomson scattering diagnosti c. In addition, the plasma wave amplitude-length product and temporal duration were independently measured through time and frequency resolv ed forward scattering, The transverse electric and magnetic fields ass ociated with the RPW were studied by the scattering of a 2 MeV electro n beam, and the eventual heating of the plasma after the breakup of th e RPW tvas measured from the x-ray radiation spectrum. The experiments and simulations show that the RPW reaches a peak amplitude of approxi mately 30%, with the amplitude Limited by plasma blowout driven by the radial ponderomotive forces of the plasma wave. (C) 1997 American Ins titute of Physics.