COAXIAL CAVITY GYROTRON

- recent results and ongoing development work -

B. Piosczyk, H. Budig, G. Dammertz, O. Dumbrajs², O. Drumm, S. Illy, J. Jin,

M. Thumm¹, D. Wagner³

Forschungszentrum Karlsruhe, Association EURATOM-FZK,

Institut für Hochleistungsimpuls- und Mikrowellentechnik (IHM),

Postfach 3640, D-76021 Karlsruhe, Germany,

¹ and Universität Karlsruhe, Institut für Höchstfrequenztechnik und Elektronik

² Department of Engineering Physics and Mathematics, Helsinki University of Technology,

Association EURATOM-TEKES, FIN-02150 Espoo, Finland.

³ Max-Plank-Institut für Plasmaphysik, Boltzmannstr.2, D-85748 Garching, Germany

e-mail: bernhard.piosczyk@ihm.fzk.de

By modifying the geometry of the coaxial electron gun it has been experimentally demonstrated that limitations due to the built up of a Penning discharge can be avoided. In experiments with single-stage depressed collector it has been observed that the current to the insert is rising with the value of the retarding collector voltage. This effect is assumed to be related with accumulation of space charge along the beam path.

The experimental set up at 165 GHz is under modification for operation at 170 GHz in order to be able to verify the design of components of a 2 MW, CW gyrotron which is now under design in cooperation between European Associations and European microwave tube industry.