Y. Shibata et al., COHERENT TRANSITION RADIATION IN THE FAR-INFRARED REGION, Physical review. E, Statistical physics, plasmas, fluids, and related interdisciplinary topics, 49(1), 1994, pp. 785-793
Coherent transition radiation (TR) has been observed in the wavelength
range from 0.2 to 5 mm, which is emitted from bunches of 150-MeV elec
trons passing through a radiator system composed of an upstream alumin
um foil and a downstream aluminum mirror. At the beam current of 1 mu
A, the intensity at lambda = 1 mm is enhanced by a factor of 0.9 X 10(
6) compared with incoherent TR. The value of this factor is close to t
he number of electrons in the bunch. The intensity of the TR has been
observed to depend on the emission length or the length of the traject
ory of the electrons between the foil and the mirror. The angular dist
ribution of the TR intensity and its dependence on the wavelength and
on the emission length have been observed. All results are in good agr
eement with theory. Dependences of the TR intensity on the cross secti
on of the beam and on the radiation material have also been examined.
From the observed spectrum of TR, the longitudinal distribution functi
on of electrons in the bunch is derived to be approximately a Gaussian
with the bunch length full width at half maximum of 0.28 mm.