Collective sub-mm-wavelength longitudinal wakefield [MV/m] induced by the modulated current in a capillary slow-wave tube.
Peak current density J is 0.2 MA/cm^2 in the channel. Beam velocity is 0.98C. Absciss axis: [mm]. See also "A High Performance, FIR Radiator Based on a Laser Driven E-Gun". Photonics Research Developments, Editors: Viktor P. Nilsson, 2008, Nova Science Publishers novapublishers.com/catalog/product_info.php?products_id=7369