Fixed temperature, rapid response, high energy heating device

Claim 1

A fixed temperature, rapid response, heating device having a heat flux output in the range of 10 to 50 kw./ft.2, comprising a generally rectangular bar-shaped body having its width dimension parallel to the direction of heat flow through said body and perpendicular to the cross-sectional area of said body as defined by its length and thickness, said body having a width:thickness ratio in the range of 1:1 to 5:1 and having a thermal conductivity at least 1,000 B.t.u.-in./hr.-ft.2-* F., a serpentine foil electric heater substantially covering at least the major surfaces of said body for supplying heat thereto, an electrically insulating film positioned between and adhesively secured to said foil heater and said body, the total thickness of the film and adhesive layers bearing a ratio to the effective thermal conductivity of said layers in the range of 0.0002 to 0.02 hr.-ft.2-* F./B.t.u. a heat output work-contacting area, smaller than the cross-sectional area, along one longitudinal edge of said body, a temperature detecting means embedded in said body, and a proportional controller means responsive to changes in said temperature detecting means adapted to vary the power input to said foil heater to maintain a fixed temperature at said output area.