3D B field map

[dumas]

Hello,

I can see that there is a function to include 2D field maps for dipoles with BMAPXY, is there any way to go 3D?
I guess, using BMAPXY 10000 times succesively with a small length and reconstruct a 3D dipole that way isn't an option

Thanks,

Jonathan

[michael_borland]

Jonathan,

There isn't a way to do this at present, but a 3d field map capability will be available in the next release, which should come out sometime in December.

--Michael

[dumas]

Great, is it possible to upload Fig.1 and Fig.2 for FTABLE again? it looks like it didn't work:
http://www.aps.anl.gov/Accelerator_Syst ... de116.html
I am lost without examples
Thanks,

Jonathan

[michael_borland]

The missing figures have been restored in the manual.

--Michael

[yjkim]

Dear Dr. Borland,

How are you?
I guess that you are extremely busy due to many business.

Recently, JLab PEPPo (Polarized Electron for Polarized Positron Source) collaboration members
have been working for complicated spectrometor dipoles, which were used for the SLAC E166 experiments.
Recently, we borrowed the spectrometer, and we would like to use it to generate the polarized positron source with our PEPPo concept
instead of using a long undulator.

But unfortunately, their 3D fieldmaps are somewhat complicated, and they have quadrupole focusing components in the dipoles.
Therefore, we can not use a simple dipole model for the spectrometer, and
we want to know how to include the measured 3D fieldmap of the spectrometer dipoles in ELEGANT lattice file.
I also want to know how to include the measured 3D field map for a solenoid and a quadrupole.

It seems that we have to use FTABLE and MHISTORAM.
But it is not simple for us to use them.

If you upload one sample input files for FTABLE and MHISTORAM and sample 3D fieldmap files for a dipole, a solenoid, and a quadrupole,
they will be very helpful for the ELEGANT users to use them properly.

Thank you so much for your kind help!

Yujong Kim

[michael_borland]

Yujong,

Aimin Xiao, the author of the FTABLE code, is the best person to answer this. However, she is away for a while. I'm attaching some simple examples that may be helpful.

--Michael

[Jerbe]

Hello Michael,

I tried using your example for an ftable quad. It doesn't work for me and it gives the following error:

>tracking 121 particles
>24 Jun 16 11:42:42: This step establishes energy profile vs s (fiducial beam).
>24 Jun 16 11:42:42: Rf phases/references reset.
>error: Initialize FTABLE: This shouldn't happen.
>Program trace-back:

I tried making my own ftable for a radially symmetric quad lens with nonlinear field gradient. It gave the same error and I first thought it was my fault but it seems there is some issue with ftable and maybe my (28.1.0) version of elegant. Could you help me out?

Cheers,
Jan

[michael_borland]

Jan,

Yes, I think there was a bug introduced in that version. Try the latest version and let us know if the problem persists.

--Michael

[Jerbe]

Hi Michael,

thanks for your help. I updated to 29.1.0 and it works for examples and a field map my college made out of measurement data from a quadrupole. However when I plug in my field table I get the error:

error: rho = 0 in choose_theta (FTABLE). Seek expert help.

It seems something in my ftable might be wrong. I attached it. I calculated the field for a not fully linear but radially symmetric field. Maybe I violate some physical constraint? - Found the violation... i divided by zero and got NaN entries in my ftable-file

Cheers,
Jan

[michael_borland]

Jan,

I think this might be addressed by the upcoming version, but I'm not 100% sure. Could you post your lattice and command files (or simplified versions) so I can try to reproduce the problem?

Thanks--Michael