generator coupling efficiency 

in inductively-coupled plasma spectrometry
https://doi.org/10.1351/goldbook.08480
Fraction of the energy generated being used for creating and maintaining the plasma in an inductively-coupled plasma spectrometer.
Source:
PAC, 2021, 93, 647. (Glossary of methods and terms used in analytical spectroscopy (IUPAC Recommendations 2019)) on page 720 [Terms] [Paper]