Two-Frequency Notch Filters for Sub-THz Plasma Diagnostics

Modern Electron Cyclotron Resonance Heating (ECRH) systems in fusion plasma research take advantage of multi-frequency gyrotrons. This means that the frequency band of some millimeter-wave diagnostics contains more than one narrowband gyrotron-frequency line, which needs to be suppressed. Compact standard-waveguide notch filters, based on coupled waveguide resonators with rectangular cross section...