Fusion gyrotron development in the 110 GHz to 170 GHz frequency range

CPI has been developing megawatt-class gyrotrons for fusion plasma heating and current drive for a range of frequencies in the mm-wave regime. Gyrotrons at 110 GHz, 117.5 GHz, 140 GHz, and 170 GHz have been designed and fabricated, and have undergone initial factory testing. Some systems have been delivered for commissioning at fusion research facilities, while several await modification following initial test results. Design features and available test data for each design will be presented.