Development of a high vacuum, high temperature movable limiter support

A mechanism for positioning the Advanced Limiter Test II (ALT-II) limiter blades inside the TEXTOR tokamak is described. Testing of two candidate material pairs for use as gears and bearings, Nitronic 60/aluminum bronze and Nitronic 60/Nitronic 60, is also described. The lubricant was a solid film of MoS/sub 2/. The testing, done at the temperature and pressure range of the tokamak, revealed that the combination of Nitronic 60 and the softer aluminum bronze performed much better than the Nitronic 60/Nitronic 60 combination. The latter combination performed well for 24,000 cycles (48% of expected lifetime), but then experienced a sudden increase in friction due to galling. The former pair performed well, exhibiting low friction throughout the duration of the test