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

Somehow this email was going to "opal-request” which I did not know that this existed.

A 

Begin forwarded message:

From: Dirk Vandeplassche <dirkvdpla AT skynet.be>

Subject: Energy gain in compact cyclotron

Date: 21 May 2025 at 14:20:56 CEST

To: opal-request AT lists.psi.ch

Dear support,

I am trying to set up OPAL for the development of a small compact proton cyclotron, which is up to now studied with my own tools for closed orbit and for median plane tracking.

In order to compare the 2 approaches, I set up a test run: a single particle tracking starting on the closed orbit at 1 MeV, mid-dee at phase 0°, and running for 50 turns. In this machine we use harmonic 4, 4 dees so 8 gaps, a dee angle of (only!) 18° and a peak dee voltage of 8.8 kV.
With these data I would very roughly expect 40 keV of optimal energy gain per turn, so 2 MeV for 50 turns. With my own tracking tool I obtain a final energy after 50 turns of 2.995 MeV. With the OPAL-run, however, the final energy is 3.875 MeV. It roughly corresponds to a gap voltage of 7.1875 kV, which seems impossible to obtain in the given geometry and dee voltage. I note that the value is remarkably close to one would have in harmonic 6.

I attach the OPAL input file I used, called ‘NY23400.in’, as well as the ‘afterEachTurn’ file and the resulting graph. Many thanks for looking Into this issue.

Best regards,
Dirk Vandeplassche

Attachment: NY23400.in
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Attachment: NY23400-afterEachTurn.dat
Description: Binary data

Attachment: NY23400.pdf
Description: Adobe PDF document

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Description: S/MIME cryptographic signature