We are constructing and testing a diagnostic instrument to investigate, in detail, ions emanating along magnetic field lines from the plasma region of the TMX-U tandem-mirror experiment. This analyzer (of Tokamak Fusion Test Reactor design) contains parallel electric and magnetic fields, which yield ion mass and energy spatial separation, respectively. A two-dimensional array of 128 copper collector plates detects the particles. The entering ion flux is first well collimated and then focused onto the detector plane during the 180° bending in the magnetic field. This instrument is designed to measure higher particle energies than the present gridded end-loss analyzers as well as determine the energy spectra more accurately. Tandem-mirror plasma parameters to be investigated with this analyzer include end-plug potential, average central-cell-ion energy, and plasma potential in the thermal barrier and nearby regions. We plan a time resolution of up to 2 kHz for each detector.

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The "C(n.-, m -+ p) reactions were studied at T = 220 MeV. The final particles were detected both separately and in coincidence and their momenta were measured. Calculation of the excitation energy of the residual nucleus allowed clear separation of events where an outer proton was removed. The data provide detailed evidence confirming the quasielastic picture of pion knockout reactions.Evidence for this derives from the agreement between the peak energies found in the coincidence spectra and those found in inclusive spectra, from analysis of angular distributions, and from the location of peaks found in missing mass spectra. The coincidence cross section is found to account for about half of the (m. +, n. +') reaction, and about half of this in turn corresponds to quasifree knockout of the outer shell protons. Secondary processes in the (n. , m. p) reaction are found to play a much more important role than in the (n.+, m. +p) reaction.