Why Ecn changed a lot?

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CCH
Posts: 16
Joined: 16 Apr 2010, 02:04

Why Ecn changed a lot?

Post by CCH » 06 Jul 2010, 03:34

Mr Borland,
Sorry to bother you again! But I'm in trouble with the emittance in elegant.Ecnx and Ecny changed a lot when I used Kquad or set default_order=2 in run_setup. Dose this mean a real emittance growth in a real machine which I don't like? Should I change the lattice to decrease the growth?

Thanks a lot!
-----------CCH
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michael_borland
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Joined: 19 May 2008, 09:33
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Re: Why Ecn changed a lot?

Post by michael_borland » 07 Jul 2010, 09:16

CCH,

This appears to result from the very large beta functions you have, combined with somewhat large (0.5%) energy spread. This results in emittance growth due to chromatic aberrations in the quadrupoles.

You need to keep the beta functions small, around 10~20 m I'd guess.

--Michael

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