Field-reversed configuration
A prolate compact toroid with no toroidal field: a ring of plasma current reverses the external axial field inside its separatrix, so the plasma sits at high beta in a field it largely generates itself. SCPN-FRC-CORE owns the device truth of the field_reversed_configuration configuration.
What the configuration is
The FRC is the simplest compact toroid in field topology and the hardest in stability theory: with no toroidal field it is formally unstable to the tilt mode in ideal MHD, and its observed robustness is a kinetic effect ordered by how many ion skin depths fit inside the separatrix. It is formed in a theta-pinch coil by field reversal, by merging, or by rotating magnetic fields, and it is the natural target of the merge-compression scheme owned by the magneto-inertial family.
What the core owns
- the device boundary: plant and experiment truth, shot lifecycle and configuration policy for field-reversed configurations;
- the declared configuration and its consistency estimates; diagnostic semantics, reference frames and clock identity declarations;
- actuator-response model boundaries and the declared safety envelope; the device-owned CONTROL adapter specification;
- the binding to the SCPN Phase Orchestrator reactor registry (version 1.0.0) and the machine-readable domain manifest.
What it explicitly excludes
- The pulsed FRC merge-compression workflow, trigger and RTL: SCPN-MIF-CORE (magneto-inertial family); spheromak: SCPN-SPHEROMAK-CORE; tokamaks: SCPN-TOKAMAK-CORE.
- Solver mathematics and validation evidence: SCPN-Fusion-Core, the canonical owner of shared solver surfaces, until an exact surface passes the reactor family migration gate; no solver code exists in, or was copied into, the device core.
- Typed signal semantics and comparability: SCPN-Phase-Orchestrator (review-only output, never actuation).
- Control admission and action formation: SCPN-Control is the sole software authority that forms an admitted control action.
- Machine protection: independent systems retain the final veto. Portfolio presentation, identity, entitlement and execution gating: SCPN-Studio.
Level-0 physics and its anchor
Radial pressure balance across the separatrix — the plasma pressure at the null carries the whole external magnetic pressure, \(p_{\max} = B_e^2/2\mu_0\); averaging over the separatrix cross-section gives \(\langle\beta\rangle = 1 - x_s^2/2\) and, with a declared density, the summed electron and ion temperature — and the empirical kinetic-scale bound \(S^*/E < 3.5\) with \(S^* = r_s/\delta_i\) and \(E = l_s/2r_s\); a test drives two configurations differing only in separatrix length across the bound and proves the verdict turns there. The Alfvén speed of the same operating point, with the proton–deuteron ordering tested rather than asserted.
Anchored on Zhu & Wu (arXiv:2607.11908v1), Table I, as-built Yingguang-1 hardware: coil inner diameter 12.4 cm, hence the coil radius 0.062 m; active coil length 36 cm; eight coils on a 4.5 cm pitch; fill density \(2\times10^{15}\,\mathrm{cm^{-3}}\); the working ion. Declared, and said to be declared: the separatrix radius, the separatrix length and the external field — that paper's separatrix radius is a simulation result printed as "approximately 1 cm", not a device dimension, and is therefore not used as an anchor; the paper prints coil currents, not a field. The bound 3.5 is equation 14 of Bala, Zhu, Li et al. (arXiv:2204.07978v1).
Load the Yingguang-1 coil in the explorer →
Non-claims
- No equilibrium, stability, compression or transport equation is solved; every number is a closed-form evaluation on a declared operating point.
- The kinetic-scale bound is empirical and orders operating points; a configuration inside the bound is not claimed stable, and the field is named
within_boundfor that reason. - The split of the total temperature between electrons and ions is not modelled and is not claimed.
- No yield, gain, reactivity, confinement or breakeven statement is made, and no value describes or validates a real machine.
Capabilities and evidence
Evidence maturity computational_prototype, five implemented capabilities, each with its evidence record in VALIDATION.md: the device configuration model (validated parameter objects with documented consistency estimates, canonical serialisation, a data-only SPO registry pin); the diagnostic and clock semantics model (synthetic channel and clock declarations aligned fail-closed with the pinned SPO observability catalogue, typed frames, clock topology, signal inventories); level-0 device physics (the closed forms on this page); the device 3D model and the device CAD model (tessellated on the shared kernel library and built again as exact solids). No parameter set or channel describes any real machine or diagnostic; the claim inventory is empty and verified by the domain validator.