Patent ID: 7164103

Claim:
An electrical resistance element comprising: a glow zone and two power supply terminals, wherein the glow zone of the element is tubular; a union extending from each of respective power supply terminals to respective ends of the glow zone, wherein each union is tubular throughout its length and has substantially the same outer diameter as the glow zone, and wherein each union has an end facing towards the glow zone; a transition region adjacent an end of each union and glow zone end, the transition region having a progressively decreasing wall thickness in a direction from the union towards the glow zone, wherein the glow zone has substantially the same inner diameter as the largest inner diameter of the transition region, and wherein the successively decreasing wall thickness is defined by a transition region inner surface having a radius that follows the function r = ro lo ⁢ l , where l is a position along the longitudinal axis of the union, r is the inner radius of the transition region at position l, lo is the overall length of the transition region along which the wall thickness decreases, and ro is the largest inner radius of the transition region.