A Poloidal Rotation Diagnostic was installed on TFTR for the final DT experiments in the spring of 1997. This spectrometer was designed to measure the poloidal velocity to determine the radial electric field in the plasma. The instrument consists of a quartz window vacuum interface, two vertically opposed fan shaped arrays of 1 mm quartz fibers and lens system. A camera spectrometer for the system is located in an adjacent room.

The design requirements and short design-to-implementation schedule led to some unique design features. In order to minimize errors introduced by the toroidal velocity component of the measurement tight position requirements were placed on the alignment of the fiber optic assemblies relative to the tokamak and to each other. The activation and contamination of the TFTR vacuum vessel presented unique design problems on how to install and precisely align the optics to 1 part in 1000 from outside the vacuum vessel. The design progressed from concept to implementation in less than 6 months which required that a relatively simple design be used.

This paper is limited to the discussion of the physical characteristics of the instrument, alignment methods and the design features. The alignment tooling and fixtures will also be presented.

*Work supported by U.S. DOE Contract No. DE-AC02-76-CHO3073.