Author/Authors :
Schmid، نويسنده , , M. and Choudhury، نويسنده , , A. Roy and Dammertz، نويسنده , , G. and Erckmann، نويسنده , , V. and Gantenbein، نويسنده , , G. and Illy، نويسنده , , S. and Jelonnek، نويسنده , , J. and Kern، نويسنده , , S. and Legrand، نويسنده , , F. and Rzesnicki، نويسنده , , T. and Samartsev، نويسنده , , A. and Schlaich، نويسنده , , A. and Thumm، نويسنده , , M.، نويسنده ,
Abstract :
Parasitic beam tunnel oscillations have been hampering the series production of gyrotrons for W7-X. This problem has now been overcome thanks to the introduction of a specially corrugated beam tunnel. Two gyrotrons equipped with the new beam tunnel have fully passed the acceptance tests. Despite excellent power capability, the expected efficiency has not yet been achieved, possibly due to the presence of parasitic oscillations suspected to be dynamic after-cavity-oscillations (ACIʹs) or due to insufficient electron beam quality. Both theoretical and experimental investigations on these topics are ongoing. On previous W7-X gyrotrons collector fatigue has been observed, not (yet) leading to any failures so far. The plastic deformation occurring on the collector has now been eliminated due to the strict use (on all gyrotrons) of a sweeping method which combines the conventional 7 Hz solenoid sweeping technique with a 50 Hz transverse-field sweep system.
ng in 2013, the gyrotron test facility at KIT will be enhanced, chiefly with a new 10 MW DC modulator, capable of testing gyrotrons up to 4 MW CW output power with multi-stage-depressed collectors.
Keywords :
ECRH , Gyrotron , Beam tunnel , Parasitic oscillations , Multi-stage depressed collector , FULGOR