Determining wave fields from perturbed particle orbits.

We test a procedure for determining electric fields over a finite volume based on measurements of a space, time, and velocity resolved measurement of a velocity distribution function at a single location. The technique is based on an exploitation of the non-local dielectric response of weakly-collisional plasma. As an example, we consider electron plasma waves in a 1-D simulation with periodic boundary conditions. Previously, it was found that ion-acoustic fields over a finite volume can be determined from a local measurement of the ion distribution function directly by means of an integral transform introduced by Morrison [1]. That technique cannot straightforwardly be applied in circumstances where one needs to perform a Fourier transform in space in order to construct the Morrison transform. Since most wave modes require Fourier transformation, it is of interest to generalize the procedure so that it can be applied to the more general case. The new procedure is tested for the electron plasma wave is with numerically generated data from a Vlasov code.

[1] F. Skiff, H. Gunell, A. Bhattacharjee, C. S. Ng, and W. A. Noonan, Phys. Plasmas 9 pp 1931-1937 (2002).