What Secondary Electron Emission (SEE) / Photoelectron Emission models is SPIS using?

I have been looking through the publications listed on this website for the SEE/ Photoelectron emission models but have not found any direct descriptions for this. I am wondering if someone can point me to any documentation going into detail on these models or can let me know how these emission currents are being calculated. Thank you!

Hello Tyler!

The documentation is there, but it’s a bit convoluted to get to it. If you browse the documentation folder (index.html), you can find a link to [SPIS/NUM Controlling NUM from UI], and there within in it links to various emissions and in the functions of these emission, there are details on how/why it works like it does.

Since I’m in the process of topic on discussion on the SEE , I have the relevant SEE documentation in my clipboard, here it is:

Description : Electron backscattering yield (or albedo).

This function is:

  • based on NASCAP electron albedo model described in section 3.4.1 of “a three dimensional dynamic study of electrostatic charging in materials”, Katz et al., NASA CR-135256:
    elctron albedo is eta0 ^ cos(theta), with
    eta0 = { log(E[eV]/50) / log(20) * (1-Heaviside(E[eV]-1000)) * Heaviside(E[eV]-50) + Heaviside(E[eV]-1000) } * { 0.1 * exp(-E[eV] / 5000) + 1 - (2/e) ^ (0.037 * atomicNb(material)) }
  • modified at low energy where, in contrast to NASCAP model, backscattering by dielectrics is thought to be close to 0.5 (DESP measurements at low energy + Russian allegation): a contribution is added for dielectrics (characterised by conductivity < 1e3 ohm-1.m-1):
    0.5 at 0eV decreasing exponentially with (arbitrary) 10eV decay: + 0.5 * exp(-E/10eV)

As an aside, I think this ‘0.5 at 0eV’ part of the implementation is not settled science actually, but experiments point in different directions.

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