Emittance measurement of the Naval Postgraduate School Linear Accelerator using optical transition radiation techniques

Abstract

Using Optical Transition Radiation (OTR) beam diagnostics and Dr. Rule's clear foil interferometer analytic code, the normalized emittance of the Naval Postgraduate School (NPS) Linear Accelerator (linac) has been measured: the normalized horizontal emittance of 97 pi +/- 10 pi mm-mrad and the normalized vertical emittance of 54 pi +/- 8 pi mm-mrad. The experiment was performed independently twice using a Kapton foil/silicon mirror and a nitrocellulose foil/aluminum mirror Wartski interferometer. The Kapton foil provided an initial measurement of the emittance, and provided lessons learned for the nitrocellulose foil measurement. The emittance measurement of the NPS linac indicate that the value maybe too high for most free electron laser applications, but is very useful for radiation effect studies in high temperature superconductors, hardening, beam diagnostics, and for the production of x-rays through novel mechanisms such as transition radiation and parametric x-radiation generation. The beam divergence was determined by comparing theoretically calculated OTR patterns with the experimental data OTR patterns.