HIGH POWER COAXIAL CYROTRONS

HIGH FREQUENCY, HIGH AVERAGE POWER GYROTRONS ARE REQUIRED FOR SEVERAL APPLICATIONS, INCLUDING ELECTRON CYCLOTRON HEATING STARTUP, HEATING, AND PROFILE CONTROL IN FUSION DEVICES. IN THIS PROJECT, THE USE OF COAXIAL CAVITIES AND ANOVEL GUN CONFIGURATION ARE BEING EXPLORED FOR REALIZATION OF SUCH GYROTRONS. INITIAL CALCULATIONS SUPPORTED BY SOVIETEXPERIMENTAL RESULTS INDICATE THAT AN INNER CONDUCTOR CAN SUBSTANTIALLY DECREASE THE MODE COMPETITION IN GYROTRON CAVITIES, ALLOWING THE USE OF LARGE DIAMETERS TO REDUCE OHMIC HEATING. CALCULATIONS SHOW THAT WITH A MODE SIMILAR TO ONE USED IN THE SOVIET UNION TO PRODUCE 1 MW AT 100 GHZ WITH 35% EFFICIENCY, 1 MW AT 280 GHZ CAN BE GENERATED WITH AN OHMIC HEATING POWER LESS THAN 2.5 KW/CM(2). THIS RESULT OFFERS IMPROVEMENTS OVER OTHER DESIGNS FOR THE SAME POWER AND FREQUENCY THAT REQUIRE THE USE OF SUBSTANTIALLY HIGHER ORDER MODES THAN HAVE BEEN USED TO DATE AND MAY SUFFER FROM MODE COMPETITION. IN ADDITION, THE COAXIAL CAVITY GYROTRON HAS A SMALLER DIAMETER ELECTRON GUN, WHICH RREDUCES THE COSTOF BOTH THE TUBE AND THE SUPERCONDUCTING MAGNET. IN PHASE IOF THIS PROJECT, THE PARAMETERS OF A 1-MW CONTINUOUS WAVE (CW), 280-GHZ GYROTRON WILL BE DETERMINED, INCLUDING CAVITY SIZE AND MODE, OHMIC HEATING, EFFICIENCY, GUN DESIGN, AND SUPPORT AND COOLING OF THE INNER CONDUCTOR.