Compact, high-power Terahertz source using cylindrical gratings

Summary form only given. A promising compact source of high power THz radiation which utilizes an annular electron beam and a cylindrical grating is being studied. The cylindrical grating configuration exhibits substantially enhanced performance in comparison with the classical 2-D planar gratings. In the studied source, the grating surface-wave produces strong beam bunching and generates significant power at the fundamental surface-wave frequency and at harmonics as Smith-Purcell radiation. A collaboration between Advanced Energy Systems and CEA/CESTA has been ongoing in performing proof-of-principle tests on cylindrical grating configurations producing millimeter wave radiation. Testing has been performed with a 6 mm period grating, producing power at the fundamental frequency of 15 GHz, second harmonic power at 30 GHz and although not measured, simulations show meaningful third harmonic power at 45 GHz. To date simulations have been performed at frequencies up to the THz frequency range. Simulations are ongoing using both MAGIC and VORPAL. Comparisons between these two codes will be presented and compared to the experimental results. Additionally, a three dimensional dispersion relation has been developed. A comparison between the dispersion relation and three dimensional simulations shows the potential higher order modes.