dewar(redirected from Dewars)
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James, English chemist, 1842-1923. See: Dewar flask.
a double chamber used to maintain the temperature of superconducting magnet coils near absolute zero. The outer chamber is filled with liquid nitrogen at a temperature of about -196° C (-321° F), and the inner chamber is filled with liquid helium at a temperature of -270° C (-454° F). A dewar is part of magnetic resonance imaging equipment.