[Archive] mass ratio

SPIS
#1

Message by EW:
Is it possible to modify the electron/ion mass ratio for the full pic simulation?

#2

Message by Sébastien Hess:
Hello.
With SPIS up to 5.2 it is not. But for pure electrostatic simulations you can play on the speciesDt: if you put electronDt=1E-6 and ionDt=1E-5 with plasmaDt=1E-5 , it will act as if you reduced the ion mass by 100
If you are using Spis DUST 5.2.2 you can use chemical formulas to define the species, which as a side effect allows to play with ion masses:
exemple of working formula (from the javadoc):

  • Ar+ (Argon ion)
  • CH4 (methane)
  • OH- (hydroxyle ion)
  • (CH3)2+ (ethane ion)
  • CH3(2+)(double ionized methyl ion)
  • HDO (heavy water)
  • ! 18O !(2+) oxygen 18 ion (doubly ionized)
  • D deuterium
  • T tritium
  • elements above 110 must be expressed as ! yyy.yyUxx ! with yyy.yy the mass (may be decimal or not), and xx the end of the symbol
So if you set the ion specie to ! 0.1H !+, it means you decreased your hydrogen ion mass to 0.1 amu. Note that this option was little tested so far, so if you use it and experience problems please report them on the forum. Sébastien
#3

Message by Sébastien Hess:
There is a problem with symbols in this forum!Formula between the ! signs should be between brackets.

#4

Message by Felicien Filleul:
Hi Sebastian,
I’m very puzzled by what you wrote about the speciesDt, how does it works in SPIS for a time step difference of one order of magnitude can virtually affect the mass of the ion ?
I have to say that I’m very perturbed by the functions of the populationDt and the plasmaDt.
Thank you,
Felicien

#5