Date: 2026-09-05 Purpose: 2D HTS undulator with a user-defined current source.

What it shows

A two-dimensional undulator with six thin-shell tape groups, an iron yoke, and the sp-ap.hdf5 REBCO table at 15 K. src/current.cpp defines a trapezoidal current waveform and builds it into usersource.so. Two current entries load the same library for opposite winding directions. undulator2d.pdf shows the geometry; ParamsGeo.dat holds the parameters undulator.geo reads.

data/ is on the plugin's include path as BELFEM_USER_DATA_DIR. It ships no tables; its README explains how to read a measured waveform from there instead.

Files

file	role
undulator.geo, ParamsGeo.dat	geometry (m); mesh it with gmsh
src/current.cpp, src/CMakeLists.txt	user source plugin
data/	tables for the plugin (empty)
undulator2d.pdf	sketch
input.conf	deck

Run

Build the plugin first; the deck loads src/build/usersource.so:

cd src && mkdir -p build && cd build
cmake -DBELFEM_DIR=/path/to/belfem .. && make
cd ../..

gmsh -2 undulator.geo -o undulator.msh

../../build/bin/belfem # or mpirun -np 4 ../../build/bin/belfem

Shared launcher

../scripts/Allrun generates the mesh, chooses ranks and threads, and can submit to Slurm; ../scripts/Allclean removes run output. To use them from this directory, copy the two wrapper scripts Allrun and Allclean from examples/helix/ here and run ./Allrun (./Allrun --dry-run prints the plan first). If you copy this deck out of the tree, copy examples/scripts/ along with it and point the wrappers at its new location. The launcher does not build plugins; do that step by hand as described above. Per-deck settings go in a run.conf next to input.conf; see ../scripts/README.md.