Validity of SPIS for high-density laboratory Langmuir probe simulations (ne ~ 10^21 m^-3)

SPIS
1

Dear SPIS Team,

I hope you are well.

I am currently evaluating SPIS for Langmuir probe simulations in a laboratory plasma with the following conditions:

  • ne​∼10^21m−3

  • Te​∼20eV

  • H / Ar / Air plasma

  • Electrostatic regime (no magnetic field)

  • Spherical, cylindrical, and planar probes

The goal is to simulate sheath formation and extract synthetic I–V characteristics, including spatial variations of plasma parameters in a confined vacuum chamber.

Before proceeding, I would like to confirm whether SPIS is valid or has been applied in such high-density laboratory plasma regimes, or whether its assumptions are limited to space plasma conditions.

For context, I completed my PhD under Prof. Richard Marchand (University of Alberta) and have published on PIC-based plasma–instrument interaction simulations in both laboratory and space plasma environments, including recent work on satellite plasma diagnostics.

I would appreciate your guidance on:

  • Applicability limits of SPIS for high-density plasmas

  • Any recommended scaling or numerical approaches

  • Prior similar applications, if any

Thank you for your time.

Kind regards,

Dr Saeed

2

Dear Dr Saeed

Can you clarify what physics you expect to need validation in this regime? As long as the sheath is well resolved, I expect Langmuir Probes experiments to perform well even outside of OML laws (i.e. sheath-limited theory), but I have not tested it.

SPIS-EP have been validated, which is targeting Debye lengths that are probably not too far from your regime, albeit a bit of a special case.
Best of luck,
Fredrik