Benchmarking a high-order particle-in-cell code for the simulation of a gyrotron traveling-wave tube P. Ortwein, S.M. Copplestone, C.-D. Munz, A. Marek and J. Jelonnek EPJ Web Conf., 149 (2017) 04020 Published online: 04 August 2017 DOI: 10.1051/epjconf/201714904020