PLT toroidal field coils: operational deflection measurements

The original deflection analyses on the PLT toroidal field coils predicted values much lower than those measured. Both a new analytical solution for the deflection of laminated beams and a finite element model of the PLT toroidal field coils have yielded increased deflections by including a shear deflection in the interlaminar bonding material. Initial tests have successfully employed linear variable differential transducers (LVDT's). These devices were used to measure vertical bore deflections of the TF coils with reference to the upper and lower surfaces of the vacuum chamber. Results compare favorably with data recorded during initial TF coil power tests. LVDT devices and high resistance linear potentiometers have also been used to record a change in vertical chordal length outboard of the vacuum chamber. In this arrangement the measurement equipment is affixed to the side of a TF coil. Data from these experiments also compare favorably to initial data taken during initial TF coil testing. Linearity and repeatability of all information is excellent. A system in which every TF coil is monitored and data used for real time operational decisions is a natural outgrowth of the results obtained thus far