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Future linear accelerators, as CLIC (Compact LInear Collider), are extremely demanding in terms of material properties. Traditionally accelerating structure is made of brazed OFE copper parts. For the high conducting regions submitted to mechanical fatigue, CuZr would represent an improved selection than pure copper while for regions where the highest electric field is applied a refractory metal, i.e. Mo, could result in a better performance. The feasibility of joining such materials, namely CuZr (UNS C15000) and pure Mo has been investigated. The joining method developed and investigated here consists in a vacuum brazing process exploiting a Cu-based brazing filler applied under appropriate vacuum conditions. Apparent shear strength (adapted from ASTM B898) on the joined samples was about 200 MPa.

The electrostatic levitation system, including its history and development, and techniques for non-contact thermophysical property measurements (density, surface tension, and viscosity) are reviewed. Thermophysical properties of refractory metals whose melting temperatures are over 2,000 K have been measured with an electrostatic levitator. The experimental results for vanadium, zirconium, niobium, molybdenum, rhodium, ruthenium, iridium, tantalum, rhenium, tungsten, and rhenium are presented. Comparison between theoretical calculations based on hard sphere model and measured data, as well as the necessity of microgravity conditions for this research are also discussed., 資料番号: AA0048136000, レポート番号: JAXA-RR-04-024E