FIELD: electric heaters. SUBSTANCE: heater has envelope in the form of sapphire tube accommodating resistor units in the form of wires or strips of high-heat material. Heater is provided with current leads at ends of tube and expansion devices to compensate for difference in elongation of envelope and resistor unit due to temperature variations made in the form of compressed metal bellows. Each bellows is attached on one end to one of two coolers cooled with water and arranged on ends of envelope. Second end of bellows is connected to one of current leads. Envelope is filled with inert gas or evacuated. EFFECT: high efficiency and reliability when operating at 1800-1900 C. 1 dwg
