We have measured the wake fields induced by short, intense relativistic electron bunches in a slowwave structure consisting of a dielectric-lined tube, as a test of the dielectric wake-field acceleration mechanism. These fields were used to accelerate a second electron bunch which followed the driving bunch at a variable distance. Results are presented for different dielectrics and beam intensities, and are compared with theoretical predictions.PACS numbers: 52.75.Di

We report the first experimental test of the physics of plasma wake-field acceleration performed

In experimental studies of the Plasma Wake-field Accelerator performed to date at the Argonne Advanced Accelerator Test Facilit,y, significant nonlinearities in both plasma and beam behavior have been observed. The plasma wares driven in the make of the intense driving beam in these experiments exhibit three-dimensional nonlinear behavior which has as yet no quantitative theoretical explanation. This nonlinearity is due in part to the self-pinching of the driving beam in the plasma, as the the denser self-focused beam can excite larger amplitude plasma waves. Th e se lf-pinching is a process with interesting nonlinear aspects: the initial evolution of the beam envelope and the subsequent approach to Bennett equilibrium through phase mixing.

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