Levitated dipole — a ring afloat in its own field
A plasma confined in the closed-field dipole of a magnetically levitated superconducting internal coil, where compressibility-driven turbulence can pinch particles inward and sustain centrally peaked profiles without driven current. SCPN-LEVITATED-DIPOLE-CORE owns the device truth of the levitated_dipole configuration.
What the configuration is
The magnetosphere of a planet confines plasma on the closed field lines of a dipole; the levitated dipole experiment brings that geometry into a vacuum vessel by floating a superconducting ring in the field of a coil above it, so no support crosses the plasma. The field falls steeply with distance from the ring, flux tubes expand outward enormously, and a pressure profile that is marginally stable to interchange can be very peaked in the centre — the compressibility that limits other devices here drives an inward pinch. The LDX device of Garnier et al. is the filed source: a 560 kg coil of 716 turns, charged inductively to 1.3 MA-turns, levitated in a 5 m vessel.
What the core owns
- the device boundary: plant and experiment truth, lifecycle and configuration policy for levitated-dipole devices;
- levitation-system semantics as device truth: coil cooldown, charging, levitation control envelope and catcher/failure boundary declarations;
- the declared configuration: floating-coil radius, current and mass, whether superconducting; the levitation environment's field gradient;
- diagnostic semantics, reference frames (dipole flux coordinates) and clock identity declarations; the CONTROL adapter specification; the registry binding (version 1.0.0) and the domain manifest.
What it explicitly excludes
- Magnetic mirrors: SCPN-MIRROR-CORE; magnetic cusp: SCPN-MAGNETIC-CUSP-CORE; toroidal external-coil systems: SCPN-TOKAMAK-CORE and its neighbours.
- 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
The ring as a magnet (ampere-turns, current-centroid diameter, dipole moment \(\pi R^2 NI\)); charging by flux conservation, \(I_F = (M_{CF}/L_F)I_C\); the levitation force balance in both readings of the printed relation and the required field gradient \(Mg/m\); the electron-cyclotron resonant field, the anisotropic beta and the flux-tube pressure ratio. Source: Garnier et al., Fusion Eng. Des. 81 (2006) 2371, SHA-256 verified against the papers ledger, every value read off pages rendered at 180 dpi and never off the PDF text layer.
Two printed numbers come back out of relations they were not fitted to: the resonant field at 6.4 GHz, 0.228633 T against the printed 0.23; and the floating-coil charge at a 300 A charging current, 933.19 kA-turns against the printed 930 — two inductances and a charging current printed on two different pages go through flux conservation and the printed turn count, and a fourth printed number comes out. Ampere-turns at the operational current, 1.303 MA-turns, are consistent with the printed floor "> 1.2 MA". Not reproduced: "over 1.5 MA turns" (1.303 at the operational current, 1.322 at maximum charge), checked where the numbers are largest; it anchors nothing and no input was adjusted until it appeared. Reported rather than resolved: the printed levitation relation reads literally as half the loop force balance (0.986 vs 1.973 mT; the source prints no value); two printed statements about one current differ by 1.4 % (1846.4 A induced at maximum charge vs 1820 A operational), gated nowhere. Declared, and said to be declared: the axial field gradient at the floating coil, derived so the configuration sits at a levitation margin of one; the field at the pressure peak, from the source's own beta definition; the flux-tube expansion as a consistency instrument.
Load the LDX coil in the explorer →
Non-claims
- Nothing is integrated in time; no equilibrium is solved, no transport equation evaluated, no stability spectrum computed.
- The cyclotron resonance is non-relativistic, while the source's own hot electrons reach tens of kiloelectronvolts, where the relativistic mass shift moves the resonance.
- The plasma quantities describe one published discharge of one experiment and are not a design point, an average or a projection; the source's two displaced-peak betas, 23 % and 18 %, bracket the quoted 21 % and are carried so the quoted value is visibly one of three.
- A beta above one is admitted rather than refused: the source defines its regime as \(\beta > 1\).
- No value describes or validates any real machine or shot; an anchor reproduces a number a filed source prints and nothing further.
Capabilities and evidence
Evidence maturity computational_prototype, five implemented capabilities, each with its evidence record in VALIDATION.md: the device configuration model, the diagnostic and clock semantics model, level-0 device physics (the closed forms on this page), the device 3D model and the device CAD model. No parameter set or channel describes any real machine or diagnostic.