The OPAL Discussion Forum

[Christof Metzger-Kraus <christof.j.kraus AT gmail.com>]

Hi Simon,

now I remember the problem with 270 degree magnets: SBend and RBend can't be used to deflect the beam more than 90 degrees but the algorithm in Opal-T that maps positions in ELEMEDGE to 3D only expects deflection from these two elements. Hence you have to place the alpha magnet and the beamline that contains all downstream elements manually (the latter with ORIGIN and ORIENTATION). Maybe I still find some input files for alpha magnets but they would be on my linux partition that I can't access at the moment.

Best regards,

Christof

On Mon, Feb 1, 2021 at 9:35 AM Christof Metzger-Kraus <christof.j.kraus AT gmail.com> wrote:

Hi Simon,

if the trajectory of the reference particle isn't influenced by the magnetic field then auto-phasing should work. But why do you need auto-phasing if your fields are static, i.e. are independent of the phase?

With

wienfilter_E: FMAPBLOCK, Z=1, FMAP="wienfilter_E-staticfield.t7", VOLT=0.15, APVETO = TRUE;

the auto-phasing algorithm wouldn't be applied on the element wienfilter_E but all other RF cavities.

Concerning 270 degree deflection: we had this question some time ago on this mailing list and I know that it initially didn't work correctly. I'll let you know about what solution I've found then, I think I got it working.

Best regards,

Christof

Christof

On Mon, Feb 1, 2021 at 10:17 AM Dr. Simon Friederich <s.friederich AT uni-mainz.de> wrote:

Hello Christof,

Thanks for your quick answer.
So you don't see a possibility with the auto-phasing algorithm being turned on? (Unfortunately I need it to be on; see my other mail).

APVETO = True would not do the trick?

Best regards
Simon

Am 01.02.2021 um 09:14 schrieb Christof Metzger-Kraus:

Hi Simon,

I'm not sure about 3DMagneticStatic field maps together with RF cavities. But the alternative should work just fine if you switch off the auto-phasing algorithm. And yes, you can overlap E-/B-field elements, even at the same position. Possibly you have to switch off the auto-phasing algorithm.

Best regards,

Christof

On Mon, Feb 1, 2021 at 10:06 AM Dr. Simon Friederich <s.friederich AT uni-mainz.de> wrote:

Good Morning Andreas,

I should have checked this:
Is it possible to use any fieldmap file (especially 3DMagnetoStatic fieldmaps) with an RFCAVITY element?
(There is no problem with the missing FREQ? And does VOLT apply then to the corresponding B-field?)

Alternatively: If I chose 3DDynamic with only zero E-field columns but non-vanishing B-field, does this work as expected?

And on top of that I can have E-/B-field elements in OPAL overlap (even at the same position) without problems?

Best regards
Simon

Am 30.01.2021 um 16:06 schrieb Adelmann Andreas (PSI):

Hi Simon 

Maybe there is already a way of accomplishing the following within OPAL-t, that I am not aware of, but:

The RFCAVITY element allows to implement 3DDynamic fieldmaps. Choosing FREQ=1 lets it operate like it had a static field, right?

Yes this is correct, I usually specify FREQ=1e-10

Would it be possible to extend this functionality for other static fieldmaps?
For example one could add a neutral element -- let's call it FMAPBLOCK -- that allows to import a(n arbitrary) 3D fieldmap (static E- or static B-field).
The FMAPBLOCK would be positioned as usually in the beam line with X, Y, Z and it's size is determined by the fieldmap.
If it was then possible to have multiple FMAPBLOCK elements overlap at the same position one could for example create a Wien filter (field amplitudes are regulated by the VOLT attribute like for RFCAVITY elements):

wienfilter_B: FMAPBLOCK, Z=1, FMAP="wienfilter_B-staticfield.t7", VOLT=1.2;
wienfilter_E: FMAPBLOCK, Z=1, FMAP="wienfilter_E-staticfield.t7", VOLT=0.15;

With the FMAPBLOCK, it would also be possible to simulate magnets, that can bend more than 270°, wouldn't it?
In this particular case, one could simulate e.g. an alpha magnet.

One could also simulate custom QUADRUPOLE fieldmaps as this is not yet supported by the default QUADRUPOLE elements.

I'm looking forward for your comments.

In case you again change the frequency to something like 1e-10, I think you should be able to achieve all of the above, because you have 

3D E/B fields. 

Do I miss something?

Cheers A 

Best regards
Simon

-- 
Dr. Simon Friederich
Helmholtz-Institut Mainz | Insitut für Kernphysik
Kollaboration ACID       | B
Johannes Gutenberg-Universität Mainz
Staudingerweg 18         | Johann-Joachim-Becherweg 45
55128 Mainz, Deutschland

Tel.: +49 (0)6131 39-23160
E-Mail: s.friederich AT uni-mainz.de

-- 
Dr. Simon Friederich
Helmholtz-Institut Mainz | Insitut für Kernphysik
Kollaboration ACID       | B
Johannes Gutenberg-Universität Mainz
Staudingerweg 18         | Johann-Joachim-Becherweg 45
55128 Mainz, Deutschland

Tel.: +49 (0)6131 39-23160
E-Mail: s.friederich AT uni-mainz.de

-- 
Dr. Simon Friederich
Helmholtz-Institut Mainz | Insitut für Kernphysik
Kollaboration ACID       | B
Johannes Gutenberg-Universität Mainz
Staudingerweg 18         | Johann-Joachim-Becherweg 45
55128 Mainz, Deutschland

Tel.: +49 (0)6131 39-23160
E-Mail: s.friederich AT uni-mainz.de