axial viewing mode 

https://doi.org/10.1351/goldbook.08457
Inductively-coupled plasma optical emission spectrometer configuration in which the entrance slit is aligned with the main plasma axis.
Notes:
  1. The large amount of light captured in this method, includes information from the sample of interest plus background, which can be considerable.
  2. Matrix interferences, which originate in the cooler plasma tail, can degrade precision and accuracy.
Source:
PAC, 2021, 93, 647. (Glossary of methods and terms used in analytical spectroscopy (IUPAC Recommendations 2019)) on page 714 [Terms] [Paper]