Simulation of gyrotrons using the high-order particle-in-cell code PICLas S. M. Copplestone, P. Ortwein, C.-D. Munz, K. A. Avramidis and J. Jelonnek EPJ Web Conf., 149 (2017) 04019 Published online: 04 August 2017 DOI: 10.1051/epjconf/201714904019