DEPRESSED COLLECTORS FOR GYROTRONS FOR ACCELERATOR

THIS PROJECT WILL EXAMINE THE FEASIBILITY OF DEPRESSED COLLECTORS FOR GYROTRONS FOR ACCELERATOR DRIVERS. GYROTRONS ARE POTENTIAL RF DRIVERS FOR ACCELERATORS INVOLVING VERY HIGH AVERAGE POWERS, E.G., 200 MW FOR THE 300-500 GEV ELECTRON-POSITRON COLLIDER. THE EFFICIENCY OF THE GYROTRONS WILL THEN HAVE A LARGE ECONOMIC IMPACT. DEPRESSED COLLECTORS ARE COMMONLY USED IN CONVENTIONAL TUBESFOR EFFICIENCY ENHANCEMENT, AND IT IS ESTIMATED THAT AN APPLICATION OF THIS TECHNOLOGY TO GYROTRON AMPLIFIERS COULD RESULT IN AN IMPROVEMENT OF AT LEAST 50% IN EFFICIENCY, AND A SAVINGS OF OVER $140 MILLION IN A 200 MW SYSTEM. THE APPROACH WILL BE TO APPLY AND MODIFY CONCEPTS FOR DEPRESSED COLLECTORS, DEVELOPED FOR CONVENTIONAL MICROWAVE TUBES, FOR USE IN GYROTRONS. BEAMS USED IN GYROTRONS HAVE SUBSTANTIAL PERPENDICULAR ENERGY, WHICH MUST BE CONVERTED TO AXIAL MOTION BEFORE COLLECTION. IN ADDITION, THEY ARE ANNULAR, WITH A LARGE RATIO OF GUIDING CENTER RADIUS TO LARMOR RADIUS. BOTH OF THESE ELEMENTS WILL CAUSE THE COLLECTOR TO BE VERY LARGE WITHOUT THE USE OF CAREFUL DESIGN METHODS. THESE PROBLEMS, AS WELL AS THAT OF HANDLING BEAMS WITH ENERGY SPREADS INDUCED BY THE MICROWAVE INTERACTION, WILL BEADDRESSED. A PRELIMINARY DESIGN WILL BE REALIZED FOR A DEPRESSED COLLECTOR FOR A 30 MW, 10 GHZ GYROKLYSTRON BEING DEVELOPED AT THE UNIVERSITY OF MARYLAND FOR ACCELERATOR APPLICATIONS.