Abstract
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.
1.2 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.
1.3 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate
safety and health practices and determine the applicability of regulatory limitations prior to use.
2. Referenced Documents (purchase separately) The documents listed below are referenced within the subject standard but are not provided as part of the standard.
ASTM Standards
F8 Recommended Practice for Testing Electron Tube Materials Using Reference Triodes Withdrawn.
Keywords
electron emitters; electron tube materials; thermionic constants; work function ;
ICS Code
ICS Number Code 01.040.31 (Electronics (Vocabularies)); 31.100 (Electronic tubes)
DOI: 10.1520/F0083-71R13
ASTM International is a member of CrossRef.
ASTM F83