Shown here is a device for exercising multi-layer high density
flexible cables. The cables in our BTeV collider experiment must survive
in a very high radiation environment inside a vacuum for 10 years. It is
thus necessary to flex them in a manner identicle to that inside the
vacuum vessel. To do this one end of the cable is kept at -10C and the
other at room temperature. Flexures occur at a rate of about 20 minute.
This particular cable was flexed more than 500,000 times with the
developement of only a single harmless microfracture. This is easily
seen as a drop in the current flowing in the cable in the figure here.
Note that the current dropped by only 2 parts in 40,000. The changes in
the slope reflect changes in the ambient air temperature in this
particular test. Future tests will be done in a vacuum chamber.