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THE ENERGY TRANSFER MECHANISM IN SHOCK TUBE ARC-HEATED DRIVERS,
BOEING SCIENTIFIC RESEARCH LABS SEATTLE WASH FLIGHT SCIENCES LAB
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It was found in shock tube arc-heated drivers that radiation transport of energy is the primary mechanism for heating the helium driver gas. The phenomena occurring in the shock-heated driver is as follows. The energy input begins with the vaporization of a small diameter copper wire mounted on the axis of symmetry and continues as the copper vapor propagates out into the helium. A central arc is formed in the copper vapor and a helium-copper mixture moves outward behind the shock wave. The arc which directly heats the copper is localized to about 3 cm radius. The copper arc transfers energy to the copper in the outward moving helium-copper mixture by radiation. A copper atom either is raised to an excited state or ionized and the energy is transferred to the helium by collisions. Because of the high density of the helium the transfer of energy from ions and excited copper to the helium by collisions appears reasonable the lifetimes of excited states are 0 1,000 collisions. This model for the energy transfer was developed from experiments with an apparatus designed to produce typical conditions obtained in arc heated drivers. Author
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