= Cold cathode
A <cold cathode> supplies <electrons> without relying on deliberate heating for <thermionic emission>. The term describes that operating distinction rather than one universal microscopic emission mechanism.
A strong surface <electric field> can produce <field emission>; in a gas discharge, particle impact and <secondary electron> emission can sustain the supply. A cathode may still warm during operation, so cold does not guarantee room <temperature>. Comparing emitted current as a function of field, illumination or discharge conditions helps distinguish mechanisms. The source's <energy> spread, stability and emitting geometry matter when it is used in an <electron gun>.
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