Date: 2026-09-05 Purpose: Quench of a single tape: coupled magneto-thermal run with user-defined materials, defect and current.

What it shows

One 12.5 mm REBCO tape carries a transport current just above its critical current. A local defect drives part of the width normal. The coupled h-phi/T run starts at 77 K and follows the hot spot for 0.3 s. Everything a quench study needs from outside BELFEM comes through plugins:

src/matlib.cpp defines five tape materials from the measured cp, k, and rho tables in data/;
src/defect.cpp defines the defect, sized in its comments to give an effective critical current of 80 A against 137 A transport;
src/current.cpp reads the waveform from data/I_vs_t_regular_smooth.txt.

The material plugin is usermat.so; the defect and current source are compiled into userdefect.so. plot_iv.py plots the current and voltage traces the run writes to iv_results.csv. The annotated templates in src/physics/materials/example_user_*.cpp and src/numerics/sources/example_user_source.cpp point to this deck as their worked example.

Files

file	role
tape.geo	geometry; mesh it with gmsh
src/matlib.cpp	user material plugin (usermat.so)
src/defect.cpp, src/current.cpp	user defect and current source (userdefect.so)
src/user_table.hpp	two-column table reader shared by the plugins
data/*.txt	measured properties and the current waveform
plot_iv.py	post-processing
input.conf	deck

Run

Build the plugin first; the deck loads src/build/usermat.so and src/build/userdefect.so:

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

gmsh -3 tape.geo -o tape.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.