Closed Orbit Calculation

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fliller
Posts: 38
Joined: 06 Aug 2008, 14:02

Closed Orbit Calculation

Post by fliller » 10 Jan 2011, 16:43

Mike,

Timur and I are trying to do the following thing and would like your advice on the best way to proceed. We have a lattice where the dipole magnets have misalignment and etilt errors. After orbit correction we would like to know the beam transverse positions and angles relative to each dipole magnet transverse center (as opposed to the ideal orbit). What is the best way to go about this? Is it as simple as taking the orbit output from the closed orbit correction, and subtracting the misalignment at the magnet and appling the rotation matrix? Asked another way, is the output of the orbit correction is in the frame of the ideal lattice?

Ray

michael_borland
Posts: 1927
Joined: 19 May 2008, 09:33
Location: Argonne National Laboratory
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Re: Closed Orbit Calculation

Post by michael_borland » 10 Jan 2011, 17:42

Ray,

The orbit output and any other centroid output (e.g., from the &run_setup centroid file) is relative to the ideal orbit.

It might be helpful to use the &matrix_output command with individual_matrices=1. The Ci columns (i=x, xp, y, yp) will give you the displacement of the beam due to the misalignment of each element.

--Michael

fliller
Posts: 38
Joined: 06 Aug 2008, 14:02

Re: Closed Orbit Calculation

Post by fliller » 11 Jan 2011, 06:39

Michael

Thanks. In the matrix output,the Ci columns are the misalignment relative to element? If so, then this is exactly what I need.

Ray

michael_borland
Posts: 1927
Joined: 19 May 2008, 09:33
Location: Argonne National Laboratory
Contact:

Re: Closed Orbit Calculation

Post by michael_borland » 11 Jan 2011, 08:59

Ray,

The Ci are the displacements that the element applies to the beam that enters on the ideal trajectory, so yes, I think you could call them the misalignment relative to the element's nominal position. For dipoles, it is relative to the entrance coordinates.

--Michael

fliller
Posts: 38
Joined: 06 Aug 2008, 14:02

Re: Closed Orbit Calculation

Post by fliller » 11 Jan 2011, 10:50

Mike,

I thought I understood this, but now I think I don't. If I have a manget that has a horizontal misalignment x_mag, and I have the closed orbit at that element x_clo. I am most interested in x=x_clo-x_mag, so the beam position relative to the center of the magnet. However, if I pull up the closed orbit, the matrix output, and the parameter list, I would expect to take the closed orbit from the previous element (since that gives me the beam position at the start of the dipole) and subtract off the DX parameter of the magnet, this would give me what I want. If I understand you correctly, you tell me that if I do

&matrix_output
printout_order = 1
full_matrix_only = 0
SDDS_output = %s.matrix
SDDS_output_order = 1
SDDS_output_match = B?0
individual_matrices = 1
output_at_each_step = 1
&end

The C1 column would be this difference. However, then I try this, I do not get x_clo-x_mag.
I have attached a lattice file. Run with -macro=tgname=seed -macro=Energy=200 -macro=UseLat=BoosterInjection20101220 -macro=seed=186873
Attachments
BoosterInjection20101220.lte
(4.47 KiB) Downloaded 828 times
MakeArbErrors.ele
(6.57 KiB) Downloaded 769 times

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