Dear All,
Our lattice has two doglegs separated by a drift space. Before and after these two doglegs, I have three quads followed by a screen. I used all these six quads, to cancel the dispersion at the screen. In other words, my lattice in symbolic letters can be represented as:
Q1 Q2 Q3 D1 D2 D3 D4 Q4 Q5 Q6 Screen.
Background: In a SLAC study, they put a 'weak' skew quad in front of dipole 3 in a chicane. The skew quad couples x with yprime.Since x is dominated by dispersion at D3, the skew quad connects z (x=eta*chirp*z) and yprime. On transporting this yprime downstream to the screen, we have x vs z like a streak camera (after canceling the x-dispersion). This is a technique used in SLAC to study CSR effects.
For my lattice, I tried to apply the same principle. I optimized the values of the six quads using elegant so that my dispersion is zero at the screen. When I turn on the skew quad, instead of getting a vertical streak at the screen, I get a tilted streak. In other words, x vs y is not a vertical line! My first culprit was that may be dispersion is not canceled completely, but when i checked for values from elegant, it was small order of 1e-17.
When i plot x vs yat the screen...there is a tilt!When I turn on the skew quad, all I should see is a vertical line . I am very confused.
When i plot x vs z at the screen...there is a huge correlation as well but elegant reports the dispersion (R16 is zero).
What is going on here? What could i do to remove the tilt? Any insights....thnx ..
regards,
Charles
using elegant: skew quad for CSR studies
Moderators: cyao, michael_borland
using elegant: skew quad for CSR studies
- Attachments
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- lattice8.lte
- This is the lattice file. Right now, skew01 is set to k1=-1.5...To turn off, set k1=0
- (4.96 KiB) Downloaded 870 times
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- A0_Xchgr.ele
- This is the ele file. I have tried to set the dispersion to zero.
- (3.31 KiB) Downloaded 874 times
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michael_borland
- Posts: 1959
- Joined: 19 May 2008, 09:33
- Location: Argonne National Laboratory
- Contact:
Re: using elegant: skew quad for CSR studies
Charles,
Can you also post the file CavOnMatrix.txt and any other files needed to run your simulation?
--Michael
Can you also post the file CavOnMatrix.txt and any other files needed to run your simulation?
--Michael
Re: using elegant: skew quad for CSR studies
Hi Michael,
Please see the attached.
regards,
Charles
Please see the attached.
regards,
Charles
- Attachments
-
- CavOnMatrix.txt
- File that describes the RF TM110 cavity..Not used in this simulation.
- (395 Bytes) Downloaded 843 times
-
michael_borland
- Posts: 1959
- Joined: 19 May 2008, 09:33
- Location: Argonne National Laboratory
- Contact:
Re: using elegant: skew quad for CSR studies
Charles,
Your skew quad is at a location with very large betax and betay. Hence, it couples x and y motion together because of the non-zero emittances. I think you need to have a beta function waist at the location of the skew quads and at the final observation point.
--Michael
Your skew quad is at a location with very large betax and betay. Hence, it couples x and y motion together because of the non-zero emittances. I think you need to have a beta function waist at the location of the skew quads and at the final observation point.
--Michael