The OPAL Discussion Forum

[Dirk Vandeplassche <dirkvdpla AT skynet.be>]

Many thanks, Daniel, for the hint. The phases are indeed clue to solving the issue.

I have another question. Would it be possible to obtain a detailed description of the text file containing the electric field map, which is then transformed by ‘ascii2h5block’ into a binary file as an input to OPAL (cyclotron type BANDRF) ?

For now, in my case, ‘ascii2h5block’ does not give any error message, but OPAL gives the error message Couldn't determine type of fieldmap in file “efield.h5part”.

Many thanks in advance,

Dirk

On 26 May 2025, at 14:39, Daniel Winklehner <winklehn AT mit.edu> wrote:

Hi All,

 

Could it be the phases? I think the phase of the second gap of a double-gap cavity would have to be gap1_phase + 180? Since two SINGLEGAP cavities are used to mimic one double-gap cavity.

 

Best,

   Daniel

 

 

From: opal-developers-request AT lists.psi.ch <opal-developers-request AT lists.psi.ch> On Behalf Of Adelmann Andreas
Sent: Monday, May 26, 2025 13:32
To: opal AT lists.psi.ch
Cc: opal-developers AT lists.psi.ch
Subject: [opal-developers] Fwd: Energy gain in compact cyclotron

 

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