PPPL-3278 is available in pdf or postscript formats.

The TFTR E||B Spectrometer for Mass and Energy Resolved Multi-Ion Charge Exchange Diagnostics

Authors: S.S. Medley and A.L. Roquemore

The Charge Exchange Neutral Analyzer diagnostic for the Tokamak Fusion Test Reactor was designed to measure the energy distributions of both the thermal ions and the supra thermal populations arising from neutral beam injection and ion cyclotron radio frequency heating. These measurements yield the plasma ion temperature, as well as several other plasma parameters necessary to provide an understanding of the plasma condition and the performance of the auxiliary heating methods. For this application, a novel charge-exchange spectrometer using a dee-shaped region of parallel electric and magnetic fields was developed at the Princeton Plasma Physics Laboratory. The E||B spectrometer has an energy range of 0.5 less than or equal to A(amu) E(keV) less than or equal to 600, and is designed to provide mass-resolved energy spectra of H+, D+, and T+ (or 3He+) ion species simultaneously during a single discharge. The detector plane exhibits parallel columns of analyzed ions, each column containing the energy dispersed ions of a given mass-to-charge ratio. The detector consists of a large area microchannel plate which is provided with three rectangular, semi-continuous active area strips, one coinciding with each of the mass columns for detection of H+, D+, and T+ and each mass column has 75 energy channels. The design and performance of the E||B spectrometer is described in detail, including the effects of exposure of the microchannel plate detector to magnetic fields, neutrons and tritium.