Progress on 140 GHz, 1 MW, CW series gyrotrons for W7-X

The construction of the 140 GHz, 1 MW CW gyrotrons for the 10 MW ECRH system of the stellarator W7-X at IPP Greifswald is ongoing. While acceptance testing of the gyrotrons is progressing, reliable output parameters and stable production have been achieved. This report summarizes the actual status and some topical results. Focus is put on the final construction and latest parameters measured at factory-acceptance tests and site-acceptance tests. Parallel to the design optimization a new spectral measurement method has been developed, which allows time-dependent broadband spectral measurements with µs resolution for ms range pulses. Results of measurements done with W7-X gyrotrons are shown.