EUROFER-97 is the reduced-activation ferritic-martensitic steel that RadCluster uses as its reference host material. Its declaration is in two places:

radcluster_code/py_utils/materials/eurofer97/declaration.py declares the graph
radcluster_code/cpp_utils/materials/eurofer97/rate_kernels.cpp holds the kernel arithmetic of the production solver

The declaration

The function build_eurofer_rag() takes the loaded parameters (InputData) and the precomputed rate constants (ReactionRates), and returns the graph and the state layout:

rag, layout = build_eurofer_rag(input_data, reaction_rates,
                                equations="bin_moment", cascade="fusion")

equations is "discrete" or "bin_moment"
cascade is "fission" or "fusion". It selects the cascade production spectrum and the helium reduction (see State-space reductions)

Every simulation object carries the result as sim.material_rag and sim.state_layout, so that a run can be inspected for the reactions it admits.

Populations

Population	Polarity	Content
bulk-111	SIA	glissile 1/2<111> loops and small 3D-mobile clusters. It holds the SIA monomer pool and receives all cascade SIA production
bulk-100	SIA	sessile <100> loops. They do not glide and have no cascade source
bulk	vacancy	vacancy clusters and helium-vacancy cavities. It holds the vacancy monomer pool

Helium is the single resolved gas species.

Processes and edges

The kernel library covers the processes P1 to P8. Each one is declared as one or more Edge families.

Process	Physics	Edge classes
P1	vacancy-SIA recombination	RECOMBINATION
P2	point-defect absorption by cavities	GROWTH, SHRINKAGE
P3	point-defect absorption by dislocation loops, with bias factors	GROWTH, SHRINKAGE
P4	loss at fixed sinks: network dislocations, grain boundaries, precipitates	SINK
P5	thermal emission of monomers	DISSOCIATION
P6	interaction of SIA clusters with cavities, with mixed 1D/3D transport of glissile SIA clusters	ANNIHILATION
P7	helium trap mutation	GROWTH
P8	radiation re-solution of helium	SOLUTE_TRAPPING

Same-polarity cluster-cluster reactions are declared as COALESCENCE edges, and the cascade source is declared with two SOURCE edges, one per polarity.

Loop-character conversion

The two SIA populations are coupled by the conversion of 1/2<111> loops into <100> loops. Three edges carry it:

a unary INTER_POPULATION transformation, which is the thermodynamic channel
a binary junction COALESCENCE of two 1/2<111> loops, whose product is a <100> loop
a COALESCENCE in which a <100> loop absorbs a 1/2<111> loop

The collision kernel of two 1/2<111> loops is split between self-coalescence and junction formation, so that the total collision rate is conserved.

Transport and solute trapping

Point-defect diffusivities follow \(D_\alpha = a^2 \nu_\alpha \exp(-E_m^\alpha / k_B T)\). Dissolved solutes retard migration through an effective jump frequency

\[ \omega_\alpha^{eff} = \frac{\nu_\alpha \exp(-E_m^\alpha / k_B T)}{1 + \sum_s z_s c_s \exp(E_b^{\alpha s} / k_B T)} , \]

which is applied to SIAs, vacancies and helium. Glissile SIA clusters migrate in one dimension, with a mean-free-path correction for rotation and trapping. The mobility cut-offs i_mobile and v_mobile set which cluster sizes take part in coalescence and in one-dimensional reactions.

Python modules of the material

File	Content
input_data.py	reads the input workbook and computes derived quantities (see Input workbook)
defect_production.py	cascade production fractions for the fission and fusion spectra
binding_energies.py	void capillarity, helium equation of state, loop binding, trap mutation
loop_energetics.py	free energies of 1/2<111> and <100> loops
reaction_rates.py	precomputed rate-constant arrays for all processes

See also: Adding a host material, Reaction Admissibility Graph