DEVELOPMENT OF A HIGH JC, LARGE DIAMETER STRAND FOR HIGH FIELD MAGNETS

ACCELERATORS UNDER CONSIDERATION HAVE MAGNET SYSTEMS THAT CONSTANTLY REQUIRE FINE FILAMENT CONDUCTORS WITH HIGH CURRENT DENSITIES AT HIGH FIELDS IN LARGE DIAMETER STRANDS. IN RECENT YEARS, MATERIAL HAS BEEN PRODUCED IN FINE WIRE FORM WITH VERY PROMISING PROPERTIES. IN ADDITION, MANY OF THE PROBLEMS OF MAKING HIGH CRITICAL CURRENT DENSITY (JC), HIGH FIELD CONDUCTORS HAVE BEEN SOLVED. THE PRINCIPAL PROBLEM THAT REMAINS IS TO CREATE SUFFICIENT "EFFECTIVE STRAIN SPACE" TO INTRODUCE THE NECESSARY NUMBER OF HEAT TREAT- MENTS TO ACHIEVE THE VERY HIGHEST JC IN THE LARGE DIAMETER WIRES. WORK ON A PREVIOUS PROGRAM INVOLVING LOW TEMPERATURE EXTRUSION INDICATED A PROMISING METHOD. WHEN MATERIAL IS EXTRUDED AT RELATIVELY LOW TEMPERATURES, THE EFFECT OF COLD WORK AND PREVIOUS HEAT TREATMENTS IN THE STRAND USED TO PACK BILLETS IS MAINTAINED, ENABLING THE AVAILABLE STRAIN SPACE TO BE GREATLY ENLARGED. THIS PHASE ISTUDY INVESTIGATES THE POSSIBILITY OF USING LOW TEMPERATURE EXTRUSION AND MODIFIED HEAT TREATMENT PROCEDURES AS A WAY OF ACHIEVING HIGH JCS IN LARGER DIAMETER WIRES.