A study of the seizure problem with high current filament feedthroughs in plasma generatorsFunded under: FP1-FUSION 9C
Diffusion bonding of the filament support stem to the chuck in the plasma sources used for neutral injection systems presents problems in the routine replacement of the large diameter tungsten filaments. In some instances the original chuck has been modified by increasing the slot depth. This solution removes the problem of cracks developing from the base of the slot and does not suffer from bonding, as no nut or thread is used. Where this cannot be done, a new nut and collet type of chuck has been designed. This has been tested using different nut materials- molybdenum, stainless steel and nickel- and with or without graphite and boron nitride as anti-seizure agent on the threaded stem. It was found that bonding can be avoided by using nickel nuts on molydenum stems or by the use of colloidal graphite as an anti-seizure agent with either molydenum or nickel nuts. Other materials were not successful.
Bibliographic Reference: Report: JET-P(88)25 EN (1988)
Availability: Available from the Publications Officer, JET Joint Undertaking, Abingdon, Oxon. OX14 3EA (GB)
Record Number: 198910711 / Last updated on: 1994-12-01
Original language: en
Available languages: en