DIAGNOSTICS OF AN ELECTRON-BEAM OF A LINEAR-ACCELERATOR USING COHERENT TRANSITION RADIATION

The three-dimensional distribution and the divergence of electrons in a bunch have been determined for a short-bunch beam of an L-band linea r accelerator by the observation of coherent transition radiation at m illimeter and submillimeter wavelengths. The transverse size of the be am and its emittance are derived as 22+/-4 mm in diameter and (4.0+/-2 .0) X 10(2) mm mrad. The longitudinal distribution of electrons in the bunch is found to be a triangular shape with a bunch length (full wid th at half maximum) of 8.5+/-1.0 mm (28 ps). An advantage of this meth od in determining the longitudinal distribution function of electrons is discussed in comparison with the conventional method using a streak camera.