Use of diffusing inductive fields of a relativistic beam-plasma system to determine plasma conductivity

As an intense relativistic electron beam passes through neutral gas it produces a plasma channel. A technique to measure the conductivity profile of this plasma is discussed. The analysis shows that diagnosing the radial and temporal variation of inductive field strengths may be used to determine both the plasma conductivity and channel radius. The essence of the method is to measure magnetic diffusion time as a function of radial position, which fixes the resistive skin depth.