- experimental results and design considerations -

B. Piosczyk, A. Arnold+, G. Dammertz, O. Drumm+, O. Dumbrajs++ , M. Kuntze,

M. Schmid and M. Thumm+


Forschungszentrum Karlsruhe, Association EURATOM-FZK, Institut für Hochleistungsimpuls- und

Mikrowellentechnik (IHM), D-76021 Karlsruhe

+ also Universität Karlsruhe, Institut für Höchstfrequenztechnik und Elektronik (IHE)

++Department of Engineering Physics and Mathematics, Helsinki University of Technology,

FIN-02150 Espoo, Finland.


Coaxial cavity gyrotrons are under investigations at FZK since a few years. The results achieved up to now have demonstrated in principle the feasibility for fabrication of a 2 MW, CW tube at 170 GHz in agreement with the needs of ITER. In order to complete the information some final experimental measurements have been prepared and will start next. In particular, the following measurements are foreseen: (1) RF-losses at the coaxial insert and its dependence on misalignment, (2) determination of the amount of diffraction losses inside the tube and (3) extension of the pulse length up to the technical limits of the experimental tube (£  100 ms) given especially by the peak power loading at the collector surface and the HV power supply.

In addition the gyrotron components as electron gun, cavity, RF-output system, collector as well as the integrated tube are examined and redesigned for their usability in a 2 MW, CW tube.

The experimental results will be presented and design solutions for the gyrotron components will be discussed.