Dear everyone:
The ion flux and the damage of the material are converted directly in many publications. But I do not know how. So is there anybody familiar with this filed and tell me how to convert ions/cm2/s into dpa/s directly?
Thanks very much!
Best Regards
Liu
It depends on the material, please look the book "Fundamentals of Radiation Materials Science" by Gary S. Was. It is shown there nicely how one can convert flux to DPA for a material under irradiation.
If you do a SRIM simulation of the situation you are concerned with, one of the ouputs is a graph of displacement damage with depth. The units are a bit obscure (displacements per ion-Angstrom AFAIR) but it is realatively easy to convert this to dpa. SRIM is easy to download and use, and if you are doing ion-irradiation work, is a must-have.
Dear Prof. Roberts. Thanks you very much!
I started to learn how to use SRIM recently. If I have further questions. May I ask you for more help?
Dear Prof. Roberts
I have learned how to use TRIM these days, but I still have one question in converting flux into dpa/s.
According to some papers, they usually give a flux of ion and convert it into a single value of dap/s directly. Like in page 1 of article Appl. Phys. Lett. 101, 191607 (2012), it says “We performed 400 keV Ne++ ions irradiation at 6*1010 ions/cm2/s, 3*1011 ions/cm2/s, and 3*1012 ions/cm2/s, corresponding to dose-rates of 7*10-5 dpa/s, 3.5*10-4dpa/s, and 3.5*10-3dpa/s … …”.
If we give a flux of the incident ions in TRIM, then we get a defects distribution. The dpa/s is different at different depth of the target. So what does the single value of dpa/s in these papers mean? Does it correspond to the max values of the dpa/s , or, the summation of dpa/s along whole depth which is equal to integration area of the plots of dpa/s vs depth?
Thank you very much!
They probably mean at the depth where the maximum dose is; but unless they specifically say, you can't be sure. Of course, to check, you can just run SRIM for the conditions they use. Be careful about whether you use the "full cascade" or "simple K-P" model; in some recent versions of SRIM, there appears to be a error in the code, which means the "full cascade" model does not give the same displacements per ion as the simple NRT model which gives the reference value for dpa. (dpa = 0.8 E(k) / (2 E(d)); but the simple K-P SRIM model is OK. Roger Stoller et al. have written a paper about this.
http://www.sciencedirect.com/science/article/pii/S0168583X13005053
Thank you very much Prof. Roberts!
If I want to calculate the total dpa/s along the whole depth, namely the integration area of the plot in the attachment, is that meaningful?
And if I want to estimate the final damage from an experiment of ion irradiation, which values of this plot should I use?
Again, thanks very much for your help!
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