Implementation of ion-ion recombination

Dear experts,

I am working on ionization chambers and I was wondering if the implementation of ion-ion recombination could be easy to do.
Hence the recombination is described, similarly to electron attachment, with a attachment coefficient \alpha~[cm^3s^{-1}] and the evolution of ion density follows

n(t) = n_0 \frac{1}{1+\alpha n_0 t}.

I have the feeling that this implementation could be quite straightforward. What do you all think ?

In my specific case the electron-ion attachment could be neglect, so it’s not relevant.

Thank you !

Pierre

Hi,

I think @hschindl is the right person to ping.

Cheers,
D

Hi,
do you have a model for the attachment parameter α?

Hello Heinrich,

No I’m still digging this direction, but I would like to experiment with it. I’m working in laboratory air, and this paper [1] proposes some measured values and a fit adjustment of \alpha as a function of temperature and humidity.
This other paper [2] suggests a fixed value of \alpha for laboratory air in dosimetry works.

And this third one [3] looks interesting, even if they study recombinations in field free regions, they highlight a relation between the recombination coefficient and the initial ion density.

[1] Franchin, A., S. Ehrhart, J. Leppä, T. Nieminen, S. Gagné, S. Schobesberger, D. Wimmer, et al. “Experimental Investigation of Ion–Ion Recombination under Atmospheric Conditions.” Atmospheric Chemistry and Physics 15, no. 13 (July 1, 2015): 7203–16. ACP - Experimental investigation of ion–ion recombination under atmospheric conditions.

[2] McGowan, S. “Ion-Ion Recombination in Laboratory Air.” Physics in Medicine & Biology 10, no. 1 (January 1, 1965): 25–40. Radware Bot Manager Captcha.

[3] Heptner, Andre, Philipp Cochems, Jens Langejuergen, Frank Gunzer, and Stefan Zimmermann. “Investigation of Ion–Ion-Recombination at Atmospheric Pressure with a Pulsed Electron Gun.” The Analyst 137, no. 21 (2012): 5105. Investigation of ion–ion-recombination at atmospheric pressure with a pulsed electron gun - Analyst (RSC Publishing).

Hi Heinrich,

Do you think that even with an incomplete model of the recombination parameter α, the implementation of recombination could still be possible, at least to verify the model in some specific cases?

Cheers,

Pierre

Hi,
sorry for the super-late reply! Yes, I think that should be possible; we would need to

  • add a function to the Medium class that returns the “recombination coefficient” as function of the electric field, and
  • adapt the algorithm in AvalancheMC (or are you using DriftLineRKF).

There is an existing function in Medium that is supposed to return the ion “dissociation coefficient” as function of the applied field. But this parameter is not used anywhere in the transport algorithms. So for testing things, we could perhaps just repurpose that function. In the end, I guess it’s quite similar in the sense that both in case of recombination and dissociation, the ion “disappears”?

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