The OPAL Discussion Forum

[Adelmann Andreas <andreas.adelmann AT psi.ch>]

Hi Seongyeol good to hear from you!

There is an example in the manual (http://amas.web.psi.ch/opal/Documentation/master/#sec.elements.multipole) that guides you how to mimic a quadrupole with a multiple, check below.

M27: MULTIPOLE, L=1, ELEMEDGE=3.8, KN={0.0,0.11};

QP1: QUADRUPOLE, L=1.20, ELEMEDGE=-0.5265, K1=0.11;

Unfortunately we do not yet have a regression test for this but looking at the implementation I am quite confident that it works :). 

In OPAL-t there are no fringe fields implemented for the multipole element. Maybe you could try to overlap a dipole with zero bending

but the multipole field. In 11.9 there is a general multipole description however to my knowledge this is not yet implemented in OPAL-t.

Cheers A

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Dr. sc. math. Andreas (Andy) Adelmann
Paul Scherrer Institut OHSA/D17 CH-5232 Villigen PSI
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On 7 Jul 2023, at 04:20, Kim, Seongyeol <seongyeol.kim AT anl.gov> wrote:

Hi Andreas,

Hello, this is Seongyeol Kim with the AWA. 

These days, I am performing the OPAL simulations to understand what the emittance growth during the beam propagation along drift-quadrupole beamline, and I would like to ask you some questions about implementing geometric aberration and fringe field of the quadrupole magnet.

• I would like to know how to use the multipole to add nonlinear filed of the quadrupole magnet (to have geometric aberration and to see the phase space distortion). 

• I am wondering if you could let me know some example of how to apply the multipole element on the quadrupole magnet to see that aberration. 
• For instance, do you have some nonlinear field of the quadrupole magnet, and the example of multipole with specific strength?

I am wondering if there is a way to add the fringe field on the quadrupole magnet. If there is, could you please let me know?

Thank you very much, and I am looking forward to hearing from you!

Best regards,

Seongyeol