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

SPIS
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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!

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Hello Tyler!

The documentation is there, but itā€™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 Iā€™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 ā€œa three dimensional dynamic study of electrostatic charging in materialsā€, 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 ā€˜0.5 at 0eVā€™ part of the implementation is not settled science actually, but experiments point in different directions.

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