Autoregulating heater

A structure comprising:

• a first member of a material having a high magnetic permeability,
• a second member of a material having a high magnetic permeability,
• said first member having a lower Curie point than said second member,
• a region of higher conductivity than said first and second members contacting both said members over a coextensive length of each,
• said structure having means for connecting said members across an alternating, constant current source such that current will flow through a coextensive length of said members to induce parallel flow of currents through said members.

A heating element comprising

• a first conductor having a large area surface,
• a second conductor having a large area surface,
• a low resistance non-magnetic layer in electrical contact with both said large area surfaces of said conductors,
• both said conductors having high magnetic permeabilities with one of said conductors having a higher Curie temperature than the other of said conductors, and
• a current return path extending generally parallel to said conductors and located adjacent to the other of said conductors and remote from said one of said conductors,
• said current return path connected in series with said conductors across a source of current.

An electrical heater having intrinsic temperature control comprising

• a center conductor having first and second ends,
• a first hollow ferromagnetic member surrounding said conductor, and having inner and outer surfaces,
• a second hollow magnetic member having inner and outer surfaces and disposed about said first member and having a higher Curie temperature than said first member,
• said inner and outer surfaces of said second and first members respectively, being disposed adjacent one another,
• a layer of non-magnetic high thermal and electrical conductivity material in electrical and thermal contact with said adjacent surfaces,
• said members and said layer having first and second ends with the first end of each said members and said layer being electrically connected to said center conductor.