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The Joint European Torus: installation, first results and prospects
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1985
Year
EngineeringFusion PowerPlasma PhysicsLight-weight Linux DistributionPressure VesselMagnetic Confinement FusionJoint European TorusPlasma TheoryPlasma SimulationControlled Nuclear FusionDense PlasmaPlasma ConfinementFusion Reactor MaterialElectrical EngineeringPhysicsMagnetic ConfinementLarge Tokamak DeviceImpurity ControlMagnetic Confinement Fusion PhysicsPontoon BridgeFusion Reactor
The Joint European Torus (JET) is a large tokamak designed to produce and study plasmas with parameters approaching those of a fusion reactor, featuring a 2.96 m major radius, 1.25 m minor radius, and a 4.8 MA plasma current. The paper aims to present JET’s design, initial Ohmic operation results, and future plans for impurity control and advanced heating. The study reports initial Ohmic‑heated plasmas and ICRF heating of H and 3He minorities in deuterium at MW power levels. Initial Ohmic operation achieved electron densities of 1–4 × 10^19 m^−3, central temperatures up to 5 keV (electrons) and 3 keV (ions), confinement times up to 0.8 s, but also revealed high radiation from metallic and low‑Z impurities.
The paper provides a brief introduction to the main aims, overall design philosophy and the planned parameter range of the large tokamak device (major radius R = 2.96 m; horizontal and vertical minor radii, respectively: a= 1.25 m, b = 2.10 m; plasma current, Ip= 4.8 MA), the Joint European Torus (JET), situated on the Culham Laboratory site, UK, whose main objective is to obtain and study plasmas in conditions and with dimensions approaching those needed in a fusion reactor. The main emphasis is on initial operation in the Ohmic-heating phase, in which results are presented covering a wide range of parameters: plasma currents Ip < 3.7 MA; toroidal magnetic fields BT= 1.3–3.4 T; elongation ratios b/a= 1.2–1.7; and safety factor values, q = 2.3–10. Average electron densities ne = (1–4) X 1019m−3, with high central electron temperatures (Te up to 5 keV) and ion temperatures (Ti up to 3 keV) have been achieved, although Zeff was in the range of 2.4–10. Energy confinement times (τE) of up to 0.8 s have been obtained. Some problems with metallic and low-Z impurities are noted, causing high radiation levels. Initial experiments, with ion cyclotron resonance frequency (ICRF) heating of H and 3He minorities in deuterium plasmas at MW levels, are reported. The paper concludes with a description of planned future experiments on impurity control, additional heating (ICRF ≈ 15 MW, and neutral injection ≈ 10 MW), and preparations for tritium operation.