Heating device
 An isothermal heating device comprises an annular tubular body providing a heating chamber for objects. Between the inner wall and the outer wall of this tubular body there is provided a plurality of separate ducts which are situated in a ring-shape about the heating chamber and which extend parallel to the tubular body axis. These ducts contain an evaporable heat transport medium and are in communication with each other preferably at one end of the tubular body. Such interconnection is in turn connected with a gas buffer reservoir containing an inert control gas. 
U.S. Philips Corporation
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F28F F28D F28D
additional inventional inventional
Jacob W. David B. George A. A. Pieter A. Adrianus P. J.
DE Ruiter Green Asselman Naastepad Castelijns