Aufbau eines Messsystems zur Bestimmung der Parameter des Millimeterwellen-Ausgangsstrahls von Hochleistungsgyrotrons

High power gyrotrons are needed for plasma heating in research experiments on generation of energy by controlled nuclear fusion. The low-loss transmission of the gyrotron output power can be performed using quasi-optical reflector lines in a fundamental Gaussian mode (TEM0,0). In this work a measuring technique is presented, which allows to determine the TEM0,0 power content in the output beam of a gyrotron and the beam radius along the propagation axis. The distribution of the power density of the beam is deduced from the temperature profile of a target, which absorbs a portion of power of the high frequency wave. An infrared camera scans the temperature profile and transmits it to a computer for data processing. Gaussian distributions are fitted to the temperature profiles by maximization of the power coupling. The beam radius is evaluated from the coefficients of the Gaussian distributions. This measuring technique has been applied to a TE10,4 gyrotron with quasi-optical output beam, which presently is under test at the KfK. The TEM0,0 power content has been measured to be 94.5%. The determined beam parameters allow a subsequent analysis of the beam generating system built into the gyrotron and the design of a matching optic, which optimally couples the TEM0,0 wave into a reflector line. (orig.)Available from TIB Hannover: ZA 5141(5400) / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekSIGLEDEGerman