In this work a novel measurement system for the analysis of the gyrotron RF output spectrum
was developed. It enables unprecedented time dependent measurements within a large bandwidth
dynamic range and unambiguous RF indication in the entire D-Band (110-170 GHz). Special
attention was given to the investigation of parasitic RF oscillations and the analysis of the
interplay of thermal cavity expansion and ionization-based space charge neutralization at the
start of long RF pulses.
