11.3.5 Neutral gas effects

a. An assessment shall be made of the plasma density around the spacecraft arising from neutral gas emissions from the EP system.

NOTE It is unlikely that the level of plasma density around a spacecraft due to neutral gas emission from EP systems can be adequately assessed using a laboratory simulation.

b. The assessment specified in 11.3.5a may be made by in-flight observations.

NOTE 1 For example, by using Langmuir probes.

NOTE 2 Otherwise, calculation or computer simulation can be used to make this assessment. This analysis is expected to take into consideration the flow rate of the gas, its temperature and its rate of ionization.