APCONTOUR element

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Youssef
Posts: 12
Joined: 13 Jun 2018, 14:50

APCONTOUR element

Post by Youssef » 14 Apr 2020, 08:35

Hi,

I tried to use the element APCONTOUR for a KQUAD or DRIFT. By twiss output, I got the aperture of the previous element.
By tracking the particle coordinates are lesser than the aperture which I have in the SDDS file for APCONTOUR. The sdds file contains x and y data.


"
S00QD1D : KQUAD , L = 1.3 , K1= 0, N_KICKS = 40
APER_STAR : APCONTOUR, resolution = 0.01, FILENAME = "cross_section_star_chamber.sdds", XCOLUMN = X, YCOLUMN = Y
S53QD11D : LINE = (APER_STAR,S00QD1D,APER_STAR)
"

How can I get the right apertures into the twiss file? or when I save the lattice ?

Thank you in Advance

Regards,
Youssef

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

Re: APCONTOUR element

Post by michael_borland » 05 May 2020, 16:21

Youssef,

APCONTOUR data won't effect the xAperture and yAperture values in the twiss_output file, because there is no way to reflect the arbitrary complexity of an APCONTOUR aperture in those two numbers.

--Michael

dondreka
Posts: 11
Joined: 25 Apr 2012, 07:38

Re: APCONTOUR element

Post by dondreka » 04 Aug 2020, 09:35

Dear Michael,

I have a related question regarding the APCONTOUR element:

I seem to understand that this element is basically a drift space with an arbitrary (polygon shaped) aperture, given that it has a length item. More importantly, it does not behave like MAXAMP, which allows to define the aperture for a subsequent element like a quadrupole (or even sequence of elements, for that matter).

While the APCONTOUR element is a very useful element for more complex apertures, the introduction of which I appreciate very much, for some of our investigations it would actually be desirable if the aperture inside a quadrupole could be specified by a polygon, i.e. having a MAXAMP like element with aperture specified as in APCONTOUR. We could use this because we have scenarios (e.g. slow extraction) where the beam comes very close to the chamber inside a quadrupole, with the maximum excursion being well inside the quadrupole. Another use case would be the determination of the loss position of particles scattered by the wires of our electrostatic septum. In those cases, defining the aperture immediately before and after the quadrupole is not enough, because that might lead to spurious transmission of particles that would actually hit the chamber inside the quadrupole.

So far, we solved this approximately by slicing the quadrupole longitudinally and checking the coordinates after each slice. Of course, this is now much easier thanks to the introduction of the APCONTOUR element. However, it would be very helpful if Elegant was able to do the aperture checking inside a quadrupole without the need for slicing.

Do you see any chance of such a feature being realizable?

Best regards,
David

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

Re: APCONTOUR element

Post by michael_borland » 05 Aug 2020, 01:34

David,

This is a very good suggestion. I'll try to get it into the next release.

--Michael

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