INVESTIGATION OF TEXTURED OXIDE CATHODE SUBSTRATES

THE OBJECTIVE OF THIS INVESTIGATION IS TO SUBSTANTIALLY EXTEND THE USEFUL PEAK AND AVERAGE CURRENT OBTAINABLE FROM OXIDE COATED CATHODES. PRESENT DAY OXIDE CATHODES ARE LIMITED TO LESS THAN 1 AMP/CM2 CW AND 6 AMPS/CM2 PULSED. THE ONLY VIABLE ALTERNATIVE AT HIGHER CURRENT DENSITY IS THE FAR MORE COSTLY DISPENSER CATHODE, WHICH REQUIRES HIGHER CATHODE TEMPERATURE, HENCE MORE HEATER POWER. THE INNOVATION TO BE TESTED IS A MICROSCOPIC TEXTURING OF THE SUBSTRATE SURFACE TO GREATLY INCREASE SURFACE AREA, REDUCE IR DROP THROUGH THE COATING AND ELIMINATE PEELING AND BLISTERING OF THE COATING. THE PROPOSED RESEARCH WILL SUPPLEMENT AN ONGOING STAR MICROWAVE OXIDE CATHODE RESEARCH PROGRAM (WHICH INVOLVES ONLY SMOOTH SUBSTRATES). IT WILL BENEFIT BY THE TEST HARDWARE AND LARGE DATA BASE DEVELOPED ON THE STAR MICROWAVE IN-HOUSE RESEARCH PROGRAM. PHASE I WILL BE USED TO DEMONSTRATE THE ADVANTAGE OF THE TEXTURED SURFACE FOR HIGHER CURRENT. THE NEW CATHODES WILL BE PERFORMANCE AND LIFE TESTED IN SPACE TUBES IN PHASE II.