RFTMEZ0 and not-so-relativistic beam capture

[broemmel]

Hi Michael,

I used bead pull data to create an on-axis field map for use in a RFTMEZ0 element. I found that for an initial low momentum beam, there was no appreciable acceleration. I split the field map into cells, put them all on the same PHASE_REFERENCE, then adjusted PHASE in the first cell and TIME_OFFSET in the last two cells to account for the initial not-so-relativistic beam. On the second pass, EZ_PEAK is successfully optimized to give the final beam energy.

Is there a better, more correct, way to account for the capture and acceleration of the first cell when using the RFTMEZ0 element? I did this according to my understanding of RFTMEZ0 items, which is probably incomplete.

Thanks, Dan

[michael_borland]

Dan,

I think what the three-cell simulation is telling you is that the distances between the cells is not right for the (variable) velocity of your beam. Given that, there isn't much you can do if the structure is already built, beyond using phase shifters for two of the cells.

--Michael