ASTM F83

This practice covers the definition and interpretation of the commonly used thermionic constants of electron emitters with appended standard methods of measurement. Cathode materials shall alternatively be evaluated by relating the temperature-limited emission to fundamental properties of the emitter, particularly the work function. Comparisons are made between emitters using the thermionic constants such as the work function, emission constant, and the temperature dependence of the work function. These thermionic constants are geometry and field effects-independent, but exhibit variations under different conditions. The pertinent equations the Richardson-Dushman equation of electron emission to evaluate the effective work function, which in turn, shall be used to find the Richardson work function and the true work function. Sample computations are also detailed.

This abstract is a brief summary of the referenced standard. It is informational only and not an official part of the standard; the full text of the standard itself must be referred to for its use and application. ASTM does not give any warranty express or implied or make any representation that the contents of this abstract are accurate, complete or up to date.

1. Scope

1.1 This practice covers the definition and interpretation of the commonly used thermionic constants of electron emitters (1, 2, 3), with appended standard methods of measurement.

2. Referenced Documents

F8 Practice for Testing Electron Tube Materials Using Reference Triodes

Index Terms

electron emitters; electron tube materials; termionic constants; work function; ICS Number Code 01.040.31; 31.100

Citing ASTM Standards

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