• J.T. Donohue
  CENBG, Gradignan
• J. Gardelle
  CESTA, Le Barp

The results of the CESTA experiment that used a flat, wide, and intense beam to produce coherent Smith-Purcell radiation are compared with 2-D and 3-D simulations performed with the PIC code "MAGIC". The comparison provides considerable support to the paradigm proposed a few years ago by Andrews and Brau.

• J.T. Donohue
  CENBG, Gradignan
• L. Courtois, J. Gardelle, P. Modin
  CESTA, Le Barp

A few years ago, a new theory for producing coherent Smith-Purcell (SP) radiation from an initially continuous electron beam was proposed. It was two-dimensional (2-D), and it has been supported by 2-D particle-in-code simulations. We report here the results of an experiment using an intense continuous flat beam that confirms the theory. A maximum voltage of 200 kV was supplied by a single-shot pulsed-power source. The beam was typically 10 cm wide and a few mm thick, with a peak current of 200 A. The laminar grating had twenty 2-cm periods, and radiation was observed at the predicted fundamental grating mode frequency near 4 GHz. The second and third harmonics were also observed at the angles predicted by the SP formula. Direct evidence for beam bunching was obtained using both a current monitor and a pick-up loop placed at the end of a groove. In general, good agreement between this experiment and theory is found.