HIGH STRENGTH, HIGH CONDUCTIVITY PLATES FOR APPLICATION IN THE COMPACT IGNITION TOKAMAK

ONE OF THE PRIORITIES IN THE U.S. FUSION TECHNOLOGY PROGRAM IS THE DEVELOPMENT AND DESIGN OF HIGH STRENGTH, HIGH FIELD MAGNETS (COPPER ALLOYED) THAT MAY BE CONSIDERED IN IGNITION DEVICES FOR BURNING PLASMA EXPERIMENTS, SUCH AS THE COMPACT IGNITION TOKAMAK (CIT). RELIABLE OPERATION WILL REQUIRE A MATERIAL POSSESSING HIGH STRENGTH, AS WELL AS HIGH ELECTRICAL AND THERMAL CONDUCTIVITY AND EXCELLENT FATIGUE CHARACTERISTICS. THE MATERIAL CURRENTLY UNDER DEVELOPMENT FOR THIS APPLICATION IS AN EXPLOSIVELY BONDED LAMINATE OF COPPER BETWEEN TWO SHEETS OF STEEL. HOWEVER, FATIGUE TESTS HAVE SHOWN THAT THIS MATERIAL IS INCAPABLE OF ATTAINING THE FATIGUE SPECIFICATION OF 30,000 CYCLES AT A STRESS OF 443 MEGA PASCALS (MPA). AN ALTERNATIVE MATERIAL FOR THIS APPLICATION IS A CUNB MICROCOMPOSITE THAT DISPLAYS HIGH STRENGTH (1,020 TO 1,360 MPA), HIGH ELECTRICAL (65 TO 75% INTERNATIONAL ANNEALED COPPER STANDARD) AND THERMAL CONDUCTIVITY, AND EXCELLENT FATIGUE CHARACTERISTICS (190,000CYCLES AT 500 MPA). THUS FAR, THESE PROPERTIES HAVE BEEN ATTAINED ONLY IN SHEETS OF 0.05 CM THICKNESS. TO MEET THE CIT FULL SCALE THICKNESS OF 1.6 CM, CONSIDERABLE SCALE-UP OF THIS STRAIN DEPENDENT MATERIAL MUST OCCUR. THE SUCCESSFUL DEVELOPMENT OF THESE PLATES IN PHASE I WOULD BE ASIGNIFICANT STEP TOWARD REALIZATION OF CIT AND ITS OBJECTIVES.