[Archive] LEO ESD Simulation

Message by Amin Ghiasi:
As you know there is a version of NASCAP called NASCAP/LEO which simulates the LEO environment. I was wondering if it is possible to simulate the LEO environment by putting the LEO parameters in SPIS? Or SPIS is designed exclusively for GEO?
Kind regards,

Message by Benoit Thiebault:
SPIS-GEO can indeed be used to model LEO environments (and most space environment in fact).
This version has just been tuned to select GEO environment characteristics by default, but the numerical kernel supports other environments.
Kind regards,

Message by Amin Ghiasi:
Dear Benoit
Thank you very much for your answer. I have run the simulation two days
ago (duration: 0.1 second) but it has progressed just by two percent so
far! I was wondering whether I should run it on a supercomputer, or there
is something wrong with my simulation? Are there any hardware requirements to run
the simulation for longer durations? Have you any experience with such difficulties
in using the software?

Message by Pierre Sarrailh:
Dear Amin,
A duration of simulation of 0.1 s in LEO is probably not sufficient to obtain a differential charging but it is a very long time in comparison to ion transport.
If we consider a typical velocity of ion in addition to the orbital velocity of the SC, the order of magnitude is 1E4 m/s. This means that the ions take 1E-5 s to cross a typical simulation box thus it is not needed to integrate the trajectory of ions over 0.1s.
A manner to treat efficiently this difference of time scales is to us the “integration duration” concept of SPIS.
To do that, you have only to fill one parameter in the GlobalParameters: PlasmaDuration. In this parameter, you can enter the maximum integration duration of ion which is a time corresponding to the typical dimension of your simulation box divided by the typical velocity of ions in your simulation.
Doing that you can gain a factor of 100 in the simulation duration.
On a general point of view, the simulation CPU time cost is very dependent on the time step and duration parameters.
Another advise, if not already done, in LEO case, you may select PICVolDistrib for the ions distribution (ionDistribX) and GlobalMaxwellBoltzmannVolDistrib for the electrons (elecDistribX).

Message by Amin Ghiasi:
Speed problem is solved, Thank you Pierre.
There was a stupid mistake I prefer not to mention!