Effect of plasma-vacuum boundary for coherent transition radiation

During the propagation of an electron bunch through the discontinuity of the (Coulomb) self-fields for the sharp boundary with different dielectric constant, a surface current of background electrons is generated, which in return emits transition radiation. In this study a comparison for temporal field profile of THZ pulse has been investigated for different quasi-monoenergetic (momentum) distribution. Our calculation shows a rather well THZ signal for higher pick quasi-monoenergetic distribution but according to experimental results, most electrons bunches follow the Boltzmann energy distribution. In our comparison, for distributions consisting quasi- monoenergetic electron, we have shown that the optimum THZ coherent radiation will occur; furthermore in smaller emission (or observation) angle it would be considerable. © 2014 National Institute of Optoelectronics. All Rights reserved.