[Archive] Modeling an RPA

Message by T.:
I was wondering if anyone has experience modeling a retarding potential analyzer with SPIS. We’d like to use three semi-transparent grids, grounding two and biasing the middle. The instrument would be measured from a collection plane behind these grids. This instrument would be placed inset in the body of a larger spacecraft.
Is this realistic to do with this code? From the “Advanced use for scientific applications” manual it seems possible.

Message by Sébastien Hess:
RPA-like simulations with SPIS have already been performed (“Characterisation of charging kinetics of dielectrics under continuous electron irradiation through real time electron emission collecting method”, by Guerch et al. 2015)
Thus, it is possible.
Now, inserting it in a larger spacecraft simulation is tricky because of the large scale differences between the analyzer and the spacecraft.
Best would be to make a simulation of the spacecraft, putting a “particle detector” instrument where the RPA should be and then use the resulting distribution to simulate the RPA.

Message by T.:
Excellent! Thanks for the resource! We were also considering that approach… it would be interest to compare the results obtained from both methods, though I agree the difference in length scales will be troublesome in one manner or another.