Cryogenic dewar and method of fabrication

A method for preparing a dewar, comprising the steps of:

• preparing a cylindrically symmetric thermal shield tail cap by
• furnishing a cylindrically symmetric tail cap mandrel,
• applying a layer of radiative insulation over the tail cap mandrel,
• applying a layer of fiberglass cloth over the layer of radiative insulation,
• applying a layer of thermal foil overlying the layer of fiberglass cloth, the thermal foil being formed of metallic thermal conductors embedded in a B-staged film adhesive matrix, the thermal conductors lying parallel to a cylindrical axis of the tail cap mandrel,
• applying a layer of fiberglass cloth overlying the layer of thermal foil, and
• consolidating the layer of radiative insulation, layer of thermal foil and layer of fiberglass cloth, and partially curing the B-staged film adhesive;
• preparing a cylindrically symmetric thermal shield body by
• furnishing a cylindrically symmetric body mandrel,
• applying a layer of radiative insulation overlying the body mandrel,
• applying an inner layer of fiberglass cloth overlying the layer of radiative insulation,
• applying a metallic screen overlying the inner layer, the metallic screen comprising unidirectional metallic wires extending parallel to a cylindrical axis of the body mandrel, and
• applying an outer layer of fiberglass cloth overlying the metallic screen;
• joining the thermal shield cap to the thermal shield body by interleaving layers of the thermal shield body and the thermal shield cap, wherein the step of joining is accomplished concurrently with the step of preparing the thermal shield body;
• and
• consolidating the joined thermal shield cap and thermal shield body, to form a dewar heat shield.

A method for preparing a dewar, comprising the steps of:

• preparing an unconsolidated thermal shield tail cap having a layer of thermal foil formed to a preselected shape, the thermal foil being formed of thermal conductors embedded in a B-staged film adhesive matrix, and a layer of insulation adjacent to the layer of thermal foil;
• consolidating the thermal shield tail cap;
• preparing a thermal shield body having a layer of a metallic heat conductor, and a second layer of insulation adjacent to the metallic heat conductor;
• joining the thermal shield cap to the thermal shield body;
• and
• consolidating the joined thermal shield cap and thermal shield body, to form a dewar heat shield.