| 摘要 |
<p>PURPOSE:To shorten time to the start of electron emission with substrate metal temperature uniformed and quickened in its rise by providing a reflection film and a sub-exothermic part having large heat capacity. CONSTITUTION:Snaking-like heating elements 5a-5c composed of three tungsten thin films are arranged on the substrate of a first heat-resistant insulation substrate 1a, and a sub-exothermic part 30 is provided facing the back surface of the insulation substrate 1a. A reflection film 7 is formed on a surface facing the cathode part 20 of a second heat-resistant insulation substrate 1b, and a sub-exothermic body 8 is formed on a surface opposite to the surface where the reflection film 7 of the second heat-resistant insulation substrate 1b is formed. When voltage is applied from a heater terminal 6, Joule heat is produced in the heating elements 5a-5c and the sub-exothermic body 8, and when substrate metals 2a-2c have a temperature of about 800 deg.C, electron emission is stably made. This enables the uniformity and quick rise of temperature in the substrate metals 2a-2c, and thereby time to the start of electron emission to be shortened.</p> |
