| Accelerator applications such as free electron lasers require short, intense, low-emittance electron beams. To attain the short beams that are required, electron bunches must be compressed longitudinally; currently, the most common method of compression is magnetic chicane compression. During chicane compression, coherent radiation is emitted; the radiation can be useful as a longitudinal bunch diagnostic, but may also distort the bunch longitudinal phase space of the electron bunches, leading to emittance growth.;This dissertation studies the coherent terahertz radiation emitted by sub-picosecond electron bunches traveling through the region of the trailing edge of the third and the leading edge of the fourth magnet of a chicane. Measurements of the far-field spectrum, angular distribution, and polarization of the radiation were performed, and an attempt was made to distinguish between the synchrotron radiation emitted by electrons bending in the constant dipole magnetic field, and the edge radiation emitted by electrons traversing the edge regions of the dipole magnets. In general, edge radiation must be calculated numerically, so a numerical code, termed QUINDI, was developed to model the radiation.;Measurements agree with numerical simulations and show that the interference between adjacent magnet edges suppresses the measured coherent edge radiation at long wavelengths. Preliminary measurements of single-magnet coherent radiation show that the characteristics of edge radiation are more pronounced than in the two-magnet case, due to the absence of interference. Energy spectrum measurements show that under full compression, the longitudinal phase space is severely distorted, most likely due to the near-field effects of the coherent radiation. The experimental set-up was also found to be useful as a non-invasive, relative bunch length monitor to optimize compression, and may be useful as a short-pulse, broadband terahertz source. |
