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...2�...2...����Hi Nigel,
Sorry as I've just realized that I'm calling the meeting at 11 instead of 10 so I completely missed it now. It's really awful as I wanted to report my status and the talk plan for the next week. I will try to compensate the mistake by putting my notes below. Sorry for the inconveniences received again. 
I hope you've got the status on our Wakes study from the group. Shortly on rectangular case we have formulas but they are not yet implemented in Merlin as they are for a single particle and we need to apply correct distribution by modes as we did for circular case before. (BTW, I need to prove for myself  that that circular currents distribution we used in MERLIN is mathematically approved. From my current understanding this is just lower frequency or small displacement approximations and we really need to convert this into Fourier-Bessel distribution to be accurate for shorter bunches. This could be done later as I tested our modes approach with different series distributions and practical bunch currents and it was practically proved that the dependency is not critical for our range of parameters.) 

Now I will concentrate on material damage study below. 
I started my study on the basis of Adriana's thesis where heat deposition on collimators from several bunches was investigated with Merlin with and without scattering. Lots of information could be received also from Beam Dump investigations results. Single particle models were studied quite well with such codes as GEANT4, FLUKA or even with the older one - MARS so we are starting from them. 
The new issue investigated recently was the effect of induced image current. The approach here is really the same as we are using for our Wakes study. It was demonstrated here that the effect could be strong enough in comparison with ionization when the bunch is close enough to the walls. 
(May be it's not relevant here but I have open question about back current induced by the beam in metal when direct heat happens. If image current is strong with near walls beam, this back current should be about the same value as the beam current itself so should be always added into account from my point of view. As I can see this was really never counted during electromagnetic showers investigations as this is really different area�).
All the possible heat deposition sources guide to instant temperature rise which can be solved by integration of the specific heat equation. Heat transfer equation can be solved separately then to get real time dependant temperature distribution between bunches. For metals we probably need to use all the parameters with real dependency of the temperature (I'm not sure in this so we could try to confirm the statement by some simple tests). The result of the analytical models can be useful to compare with simulations. ANSYS simulation can be really useful here as it can include phase transformations or melting and also cracks of the material.
George's ANSYS results from your previous notes were quite useful for me. What I started to do is to repro the same with 2D geometry as we really can ignore longitudinal shower distribution for electrons in relatively thin collimators in about 1 radiation length. What I'm trying to prepare now is some kind of macro to create ANSYS keypoints that can reflect 2D distribution to automatically repro the distribution of the real bunch. This is not finished yet but I have some progress here...

I'm preparing my presentation now which will include all the facts described above plus compilation of the useful formulas linked with the material. I hope to have some draft version of it on Friday so I will happy to send it for your critical review. 

Best regards,German

 
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