Magnetic cusp — opposed currents, central null
Devices confining plasma with opposed magnetic fields whose point and line cusps form a magnetohydrodynamically stable, everywhere-convex boundary. SCPN-MAGNETIC-CUSP-CORE owns the device truth of the cusp configuration.
What the configuration is
Reverse the current in every other coil of a solenoid and the field no longer has closed surfaces: it vanishes at a central null and leaks out through point cusps on the axis and line cusps between the coils. The boundary is convex toward the plasma everywhere, which is why the cusp is the textbook example of a magnetohydrodynamically stable open configuration; the price is that the loss apertures at the cusps are of sheath scale, and confinement is the balance between a high-beta interior and the transport out through them. Spindle cusps and picket fences are the two classical geometries.
What the core owns
- the device boundary: plant and experiment truth, lifecycle and configuration policy for opposed-field cusp devices;
- cusp-geometry semantics (spindle and picket-fence classes, point-cusp and line-cusp loss-aperture declarations) as configuration facets;
- the declared configuration: geometry kind, coil count, coil radius and separation; coil current and whether neighbouring currents are opposed;
- diagnostic semantics, reference frames and clock identity declarations; the CONTROL adapter specification; the registry binding (version 1.0.0) and the domain manifest.
What it explicitly excludes
- Polywell-style electrostatic confinement: SCPN-IEC-CORE — the SCPN registry classifies
polywellunder the magnetic-open family for its cusp topology, but the portfolio standard assigns the device to the electrostatic owner because its energy and reaction workflow is an electrostatic potential well; this core owns purely magnetic cusp confinement only. - Magnetic mirrors (axial mirror-force confinement): SCPN-MIRROR-CORE; levitated dipole: SCPN-LEVITATED-DIPOLE-CORE.
- Solver mathematics and validation evidence: SCPN-Fusion-Core, 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. Machine protection: independent systems retain the final veto. Portfolio presentation and gating: SCPN-Studio.
Level-0 physics and its anchor
No level-0 physics is implemented in this core yet. The cusp core has two implemented capabilities, the device configuration model and the diagnostic and clock semantics model; it evaluates no closed form, and the explorer of this family has no cusp tab for that reason. What it carries is the declared parameter set above, validated with documented consistency estimates and serialised canonically with a SHA-256 digest, and synthetic diagnostic declarations aligned with the pinned observability catalogue.
Non-claims
- No equilibrium, stability, cusp-loss or transport calculation exists in the repository.
- No parameter set describes or validates any real machine; no channel describes a real diagnostic.
- The repository is not machine-ready, not safety-certified and not reactor-ready; cusp-geometry and fuel-cycle choices are configuration facets, not separate claims.
Capabilities and evidence
Evidence maturity computational_prototype, two implemented capabilities, each with its evidence record in VALIDATION.md: the device configuration model and the diagnostic and clock semantics model. No parameter set or channel describes any real machine or diagnostic.