  Bunches of high charge (up to 10 nC) are compressed in length in the CTF II
magnetic chicane to less than 0.2 mm rms. The short bunches radiate coherently
in the chicane magnetic field, and the horizontal and longitudinal phase space
density distributions are affected. This paper reports the results of beam
emittance and momentum measurements. Horizontal and vertical emittances and
momentum spectra were measured for different bunch compression factors and
bunch charges. In particular, for 10 nC bunches, the mean beam momentum
decreased by about 5% while the FWHM momentum spread increased from 5% to 19%.
The experimental results are compared with simulations made with the code
TraFiC4.
