Spectrum Of Coherent Transition Radiation Research Articles

Electron bunch length measurements at the Vanderbilt FEL

Pulse compression of submillimeter long electron bunches at the Vanderbilt FEL has been observed. The bunch length is determined by analyzing the coherent transition radiation spectrum produced by the charge distribution, and we show that bunch length changes as small as 15 μm (corresponding to 50 fs) can be detected.

Coherent transition radiation at submillimeter and millimeter wavelengths.

A spectrum of coherent transition radiation (TR) emitted from 150-MeV electron bunches from a linear accelerator has been observed in the wavelength range from 0.6 to 5 mm. The intensity at a wavelength of 4 mm is enhanced by a factor of about 6\ifmmode\times\else\texttimes\fi{}${10}^{5}$ in comparison with that of ordinary TR. The factor is about a half of the number of electrons in a bunch. The intensity shows nearly a quadratic dependence on the electron-beam current. The interference between TR from adjacent bunches has been observed. The electron distribution in a bunch has been derived from the observed spectrum. It has a full width at half maximum of 0.56 mm and the shape is similar to a Gaussian function.