Photon interaction with beam-plasma induced electromagnetic turbulence

Summary form only given, as follows. Photon interaction with plasma turbulence induced by relativistic beam-plasma instability is studied by 2 and 1/2 D particle simulation code MAGIC. A relativistic beam with a typical Lorentz factor of /spl gamma/=10 to 40 and a beam density of n/sub b/=0.02n/sub o/ is used to induce the beam-plasma instability in a collisionless plasma (n/sub o/=1/spl times/10/sup 18/ m/sup -3/, T/sub c/=10 keV). The relativistic beam induces the instability through coupling between the beam-plasma mode and an electromagnetic mode resulting in electromagnetic turbulence. The observed growth rate of the instability, as a function of beam velocity and wavevector, agrees well with linear theory. Photon-plasmon interaction is studied by injecting a photon, with frequency on the order of /spl omega//sub pe/, into the plasma turbulence. The interaction between the injected photon and the plasma turbulence is analyzed in the frequency domain as well as wavevector domain. The beam-plasma induced turbulence generates wavevector modes which can couple into the photon field. Energy from the plasma turbulence has been transferred to the photon increasing the photon frequency to 2/spl omega//sub pe/. The energy absorbed is a fraction of the incoming photon energy. The interaction is found to depend on the beam-plasma instability, disappearing when the beam-plasma instability is suppressed.