| CPC H05B 3/06 (2013.01) [F23Q 7/10 (2013.01); H05B 3/44 (2013.01)] | 3 Claims |

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1. A heater, comprising:
an insulating base including a ceramic body and a ceramic cylinder, wherein a first ceramic body end of the ceramic body is inserted in the ceramic cylinder;
a heat generating resistor located inside the ceramic body;
a cylindrical ring with an open center, wherein a first ceramic cylinder end of the ceramic cylinder is inserted into the open center and the cylindrical ring surrounds a portion of the ceramic cylinder; and
a spacer which is belt-shaped, located between the ceramic cylinder and the cylindrical ring, and surrounds the ceramic cylinder in a circumferential direction, wherein
the spacer comprising a first spacer end and a second spacer end which faces the first spacer end,
the first spacer end comprises a recessed portion,
the second spacer end comprises a protruding portion,
the protruding portion is located in the recessed portion, and includes a central portion located in the recessed portion and two outer edge portions, each of the two outer edge portions extend in a thickness direction away from the ceramic cylinder, and
a thickness of the outer edge portion in a length direction of the ceramic cylinder is smaller than a thickness of the central portion.
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