Multi frequency excitation

[wtam]

Hello,

I believe a gap, and other RF components, is excited by a sinusoidal source by default.
Can a RF component be excited by a multi-frequency source or non-sinusoidal source? Please show it in the example below.

; Structure file
freq 300
DRIFT 0 100
drift 100 10
gap 100e3 30 10 0
drift 100 10;
DRIFT 0 100
END

Thanks and best regards,
Wai-Ming

[jonathan dumas]

Hello Wai-Ming,

GAP is not the best way to go.
You can create a multi-frequency source by using back to back thin FIELD_MAPS with different frequencies:
FREQ 300
FIELD_MAP 100 0.1 -90.0 10 0 3.2 0 0 FieldMapOnes
FREQ 150
FIELD_MAP 100 0.1 -90.0 10 0 -8 0 0 FieldMapOnes
Freq 75
FIELD_MAP 100 0.1 -90.0 10 0 20 0 0 FieldMapOnes

where FieldMapOnes is just a field map with a constant field over a very small length,
for example, FieldMapOnes.edz:
10 0.0001
1
1
1
1
1
1
1
1
1
1
1
1

Best,
Jonathan

[Didier]

Hi,

Yes, Jonnathan is right, this could work using the GAP element, only if the transverse divergences of the beam are not too big. This problem is caused by the thin gap RF model used in TraceWin.

Regards,

Didier

[wtam]

Jonathan, Didier,

Thanks a lot.
In case of the FIELD_MAP does not reach zero within the its length, how does TraceWin handle it?

Best regards,
Wai-Ming

[Didier]

Dear Wai-Ming,

I'm not sure to undestand your question. Anyway, in all case field_map Tools from "Charts" tab-sheet allows to visualize the field shape used for computation.
For example the Janathan's map:
FIELD_MAP 100 .1 -90 30 1 1 0 0 test

field.png (7.76 KiB) Viewed 3789 times

Regards,

Didier

[wtam]

Dear Didier,

Following your example, in the case that:

DRIFT 10 30
FIELD_MAP 100 .1 -90 30 1 1 0 0 test
DRIFT 10 30

There is a discontinuity in the field at z = 10 mm and 10.1 mm. Would that be fine?
In practice, should the data in FIELD_MAP smoothly goes to zero at the beginning and the end?

Best regards,
Wai-Ming

[wtam]

Dear Didier,

In addition to my question about discontinuity in fields in my previous message, I have two more questions about the structure of the 1D FIELD_MAP file.
(1) What does the number in the 2nd row represent (in Jonathan's example it is "1")?
(2) Can the field data be unevenly spaced?

I tried to find the answers from the user manual but I failed.

Best regards,
Wai-Ming

[Didier]

Dear Wai-Ming,

First of all, the best way is obviously to use a real rebuncher field map. The field map example given by Jonathan is just a simple way to replace the use of the usual GAP element which could have problems due to too large transverse beam divergences.
So seeing a discontinuity, which I personally don't see, is not a problem , especially when compared to a thin gap.

(1) The second parameter is noted 'Norm' in the manual and is just a coefficient applied to all field values on the map. Fz(z)=Fz(z)/norm. In reality it is useless, so keep it at 1.
(2) The step of the field maps in TraceWin format requires a constant step.

Regards,

Didier

[wtam]

Dear Didier,

Happy New Year!
While trying the superpose command I received a warning (please see attached screenshot). What am I supposed to do with it?
Thanks.

Best regards,
Wai-Ming

[Didier]

Dear Wai-Ming,

I also wish you a Happy New Year.
Don't worry about this message. If you save your project, it should not reappear.

Regards,

Didier