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Register a new userGas dynamics in high-luminosity polarized He-3 targets using diffusion and convection
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Added by
Gordon D. Cates Jr.
Publication date
2011
fields
Physics
and research's language is
English
Authors
P. A. M. Dolph
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The dynamics of the movement of gas is discussed for two-chambered polarized He-3 target cells of the sort that have been used successfully for many electron scattering experiments. A detailed analysis is presented showing that diffusion is a limiting factor in target performance, particularly as these targets are run at increasingly high luminosities. Measurements are presented on a new prototype polarized He-3 target cell in which the movement of gas is due largely to convection instead of diffusion. NMR tagging techniques have been used to visualize the gas flow, showing velocities along a cylindrically-shaped target of between 5-80 cm/min. The new target design addresses one of the principle obstacles to running polarized He-3 targets at substantially higher luminosities while simultaneously providing new flexibility in target geometry.
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We present the conceptual design of a polarized $^3$He target to be used for high luminosity scattering experiments within high magnetic field environments. This two-cell target will take advantage of advancements in optical pumping techniques at high magnetic field to create 60% longitudinally polarized $^3$He gas in a pumping cell within a uniform magnetic field above 1 T. By transferring the polarized gas to cryogenic target cell, the gas density is increased to create a target thickness suitable for high luminosity applications. We discuss the general design of this scheme, and plans for its application in Jefferson Labs CLAS12 detector.
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