Experimental studies of dense electron beam transport through diaphragms

The situation when an electron beam is transported through a system of diaphragms or a channel with transverse dimensions close to those of the beam is typical for electron-beam vacuum microwave devices. Inner surfaces of the channel or diaphragms are subjected to bombardment with particles of the beam halo. In high-power devices, this bombardment may cause non-linear phenomena having a substantial effect on transportation of the main part of the beam. We present data on processes similar to those found in developing electron-beam microwave devices with high electron beam parameters. We demonstrate the possibility of a critical influence of complicated phenomena, including generation of secondary particles and plasmas and non-linear collective oscillations, on the transport of a high-power electron beam. The investigations are performed for a broad range of conditions (beam current, energy deposition density on the electrodes surrounding the beam, etc.) and show a universality of the observed phenomena.