IH structure

[jonathan dumas]

Hello,
is there a way to do IH structures in TraceWin (without fieldmaps) for first order calculations?
Thank you,
Jonathan

[Didier]

Hi,

The NCELLS element could probably cover the need

Didier

[Lee]

The only drawback with NCELLS and IH-DTLs would be, that - afaik - the ratio of drift tube length to gap length is fixed to be 1, see the manual:

If m=1 (=π-Mode):
For cell2 to N-1:
Le=Ls=1/4 βλ,
Lc = ½ βλ,
EoT(2..N-1)= EoT.(1+kEoTi).(Ti/Ts)

This thus leads to some deviations, since in reality the outer gaps often have a different length than those in the center of a cavity.
Nevertheless, this should probably be a more accurate approximation for IH-DTLs than simply using the thin gap approximation, right?
Regards
Lee

[Didier]

Dear Jonathan,

Using Bg as following, cell length can evolve according to velocity

Geometric β
> 0: all cell lengths are the same according to βg
= 0: cell lengths are set according to beam velocity
< 0: cell lengths are set according to an initial beam velocity –βg, which is increasing from cell to cell according to θs and EoT parameters.

And outer cell lengths can be adjusted according to dzi and dz0 parameters.

That should be good enougth to simulat IH-DTLs cavities ?

Regards,

Didier

[hendrik.haehnel]

Dear Didier,
I would like to ask a question about this:

Does the NCELLS Element do anything else than produce a DRIFT GAP DRIFT calculation in the code (using thin gap approximation)? From the documentation it is not clear to me whether there is some other field approximation used or anything. You would have to assume some gap geometry for this, right?

I am asking, because Lee stated:

Nevertheless, this should probably be a more accurate approximation for IH-DTLs than simply using the thin gap approximation, right?

I am not sure about that for the above stated reasons.

Best regards,
Hendrik

[Didier]

Dear Hendrik,

Yes NCELLS element is just a succession of DRIFT and GAP, as defined for individual elements. But, the management of the RF phase according to the different possible options would still be complicated to manage manually.

Regards,

Didier

[Vyacheslav]

Dear Didier, is it correct to use five CAVSIN elements to simulate 5-gap IH cavity?
Explain, please, what does absolute and relative theta_s mean? I do not understand that clearly.
One more, how is K parameter defined for CAVSIN element?

[Didier]

Dear Vyacheslav,

This element and the equations used are fully described in the manual.
In particular, I can read, K = 2ϖ/λ = ω/c

So,I don't know if this element initially defined for CCL type cavities can be used for IH structures. I think that probabbly the best for you is to use the 1D field map (FIELD_MAP) to define the field on the axis of your specific structures.

Relative phase means that the RF phase of each cavity is independent, absolute means that they all have the same reference defined at the beginning of the machine.

Regards,

Didier