The OPAL Discussion Forum

[masao nakao <nakaom AT rcnp.osaka-u.ac.jp>]

Dear Daniel,

Thank you for kindly reply.
Simulating beam is 50keV proton of about 0.1~1mA. So space charge is 
important.
I will try to use 3D fieldmaps as you write.

Yours, sincerely,
Masao


On 2020/03/20 21:41, Daniel Winklehner wrote:
> Dear Masao,
>
> Yes, you can do it, but it requires some fiddling around at the moment.
>
> The most important question is: what beam current are you simulating? Is 
> space charge an important factor or not so much?
>
> If space charge is very important for your application, you will have to 
> compile OPAL with the SAAMG option ON. To my knowledge, there is no binary 
> package that supports usage of the SAAMG solver that you can just download, 
> but Achim can correct me on that.
>
> If space-charge is unimportant, you can use the OPAL 2.2 binary.
>
> In both cases, you will need to prepare the electric AND magnetic fields as 
> 3D fieldmaps in the center of the cyclotron as *.h5part format files. 
> OPAL-cycl, by default, uses the midplane field only and gets the z =/= 0 
> components from a series expansion. For the electrostatic inflector, you will 
> need a more accurate field description along the spiral trajectory. There 
> have been some email list discussions recently on how to transform 3D field 
> data from ANSYS/TOSCA/COMSOL to h5part using a C script called 
> ascii2h5part.cpp. I am using python with h5py, which works too. See attached 
> for electrostatic case. Resulting fields can be checked with VisIt 3.1.1.
>
> The fields can be loaded into OPAL-cycl by using the BANDRF type cyclotron 
> and loading the fields as RF cavity fields with frequency = 1e-36 (i.e. 
> static fields) and RFPHI = 0.0 and PI/2 for electric and magnetic fields, 
> respectively. The units for these fields should be kV/mm (MV/m) and mm.
>
> Finally, the geometry can be loaded as well. Firstly, as the boundary for particle termination, 
> if you are interested in the losses. Secondly, as the boundary conditions for the SAAMG field 
> solver (if you are using it). For geometry preparation, you will need the "negative" or 
> "vacuum" space rather than the individual electrodes. This is described in the paper 
> you mentioned. Just create a cylinder that encloses all your electrodes (maybe start with just 
> the spirals) and subtract the electrodes from the cylinder as a Boolean operation in the program 
> of your choice. Inventor works, so does FreeCAD (which is open source). Save as iges, stp, etc. 
> and open in GMSH. In gmsh, you can mesh your geometry and save the mesh as vtk. Achim write a C++ 
> program that translates vtk to h5block, which is the format OPAL needs for geometry.
>
> If you do use SAAMG, you have to use the "SPIRAL" cyclotron type instead of 
> BANDRF.
>
> I will write up better instructions for the whole process over the weekend 
> and provide a simple example input deck to help along with getting started on 
> this non-trivial process.
>
> Best,
>     Daniel
>
>
>
> -----Original Message-----
> From: opal-request AT lists.psi.ch <opal-request AT lists.psi.ch> On Behalf Of 
> masao nakao
> Sent: Friday, March 20, 2020 07:44
> To: opal AT lists.psi.ch
> Cc: nakaom AT rcnp.osaka-u.ac.jp
> Subject: [Opal] Fwd: 3DElectroStatic
>
> Dear OPAL developers,
>
> I would like to simulate injection system of AVF cycltoron with electrostatic 
> inflector.
> Though OPAL manual shows 3DElectroStatic is "Not implemented yet."(p.173), a 
> paper [1] shows results by OPAL. How can I calcurate like that? I have 3D electric 
> field data culculated by TOSCA.
> Thank you.
>
> [1] "Realistic simulations of a cyclotron spiral inflector within a 
> particle-in-cell framework"
> Daniel Winklehner et al.
> PHYSICAL REVIEW ACCELERATORS AND BEAMS 20, 124201 (2017)
>
> Yours, sincerely,
> Masao
>
>
> --
> Masao Nakao
> Osaka University
> Research Center for Nuclear Physics
> Mail : nakaom AT rcnp.osaka-u.ac.jp
> Phone: 06-6879-8914
> FAX  : 06-6879-8899


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Mail : nakaom AT rcnp.osaka-u.ac.jp
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