Reproduction: FRC merge / no-merge against Belova et al. (arXiv:2501.03425)¶
What this reproduces, and what it does not¶
This page reports MIF's kinematic reproduction of the merge / no-merge
outcomes in Belova et al., Hybrid simulations of FRC merging and compression
(arXiv:2501.03425; HYM hybrid code, Helion-affiliated). It drives the real
MIF-003 MergeWindowMonitor with each paper case's initial conditions in the
paper's normalised units and classifies whether the two plasmoids reach the merge
window.
It is deliberately bounded by the repository ownership rule (ADR 0001): MIF owns the kinematics, not the plasma physics. So this reproduction makes no tA-exact merge-time claim and no compression-coupled claim — the reconnection acceleration and the mirror-field compression are FUSION-owned (FUS-C.6) and are reported as a delegated gap, not modelled here.
All source constants are text-stated in the paper's §3.1–3.2 (not digitised
from figures), and are recorded with section cites in the verification register
.coordination/research/SCPN-MIF-CORE/belova_2501.03425_verified_constants_2026-06-20.md.
Method¶
Each case is a symmetric two-plasmoid constant-velocity approach in Belova units (length in ion skin depths dᵢ, velocity in v_A, time in t_A = R_c/v_A; the velocity unit in dᵢ/t_A is v_A = (S*/x_s) dᵢ/t_A). The monitor is classified as "merge" when it achieves a merge-window lock within a single calibrated availability window τ_window; the no-compression cases bound τ_window to the open interval (33.1, 49.0) t_A from the data, and 40 t_A is used.
Regenerate: python -m tools.belova_merge_parity; artifact:
bench/results/belova_merge_parity.json; drift gate:
tests/physics_parity/test_belova_merge_parity.py.
Result — merge / no-merge classification (no-compression cases): 5 / 5¶
| Case (cite) | ΔZ (dᵢ) · Vz (v_A) | Ballistic closure (t_A) | Belova outcome | MIF prediction |
|---|---|---|---|---|
| Fig 1, §3.1 | 180 · 0.20 | 12.13 | merge | merge ✓ |
| Figs 3–4, §3.1 | 75 · 0.10 | 9.94 | merge | merge ✓ |
| Fig 5, §3.1 | 110 · 0.05 | 29.15 | merge | merge ✓ |
| Fig 5, §3.1 | 125 · 0.05 | 33.13 | merge | merge ✓ |
| Fig 5, §3.1 | 185 · 0.05 | 49.03 | no-merge | no-merge ✓ |
The compression case (§3.2) is excluded from the kinematic classification: the increasing mirror field that drives it is FUSION-owned physics.
The honest gap: ballistic closure is an upper bound, not the merge time¶
Constant-velocity closure over-predicts the measured merge time, because the FRCs accelerate toward each other through reconnection — physics MIF does not model. For Fig 1 the ballistic closure is 12.13 t_A against a measured merge at ~5 t_A, a factor of ~2.4×. MIF reports this factor and delegates the acceleration to FUSION (FUS-C.6); it is not absorbed into a fitted MIF number.
Honest scope summary¶
- MIF reproduces: the merge/no-merge ordering of the no-compression cases (5/5), using its real merge-window monitor.
- MIF does not claim: exact merge times (needs the HYM physics), or any compression-coupled result.
- Constants: verified at source, text-stated §3.1–3.2, cited.