Filamentary Instability of a Relativistic Electron Beam

Abstract

The transverse electromagnetic or filamentary instability is reconsidered in light of recent experiments which were unable to suppress the instability by increasing the beam transverse temperature. I find that only the applied magnetic field can stabilize the mode. While the beam temperature can cause stabilization in a collisionless, $\nu =0\mathrm{}$, plasma, for finite $\nu$ the beam is unstable to filamentation if ${{\omega }_{\mathrm{pb}}}^2{\beta }^2\gamma >{{\Omega }_{\mathrm{ce}}}^2$, regardless of its temperature.