TY JOUR TI On Prospects of Output Power Increasing in Low-Voltage Multibeam Klystrons for Electron Accelerators KW multibeam klystron KW metamaterial KW phase velocity KW annular resonator KW dispersion JO Infocommunications and Radio Technologies AU Galdeckiy, A.V. PY 2022 IS 5 PB Federal State Educational Institution of Higher Education Sevastopol State University