Nuclear Fusion · 1974 · 87 citations · 6 references
Natural SciencesNuclear EngineeringPhysicsFusion EngineeringNuclear PhysicsPlasma PhysicsFusion PlasmasHigh-temperature PlasmasLow-temperature PlasmasPlasma ConfinementPlasma DiagnosticsPlasma InstabilitiesCurrent DensityElectrical Conductivity In PlasmasImpuritiesImpurity TransportThermal Insulation PerformanceTokamak PhysicsTokamak PlasmasTokamak Stability
Multiply charged impurities in tokamak plasmas can cool the periphery via line radiation, sharpening conductivity and current density profiles, while axial concentration may flatten them or cause a skin effect, and their influence grows with higher density, temperature, and discharge duration. The study uses soft X‑ray measurements to investigate impurity behavior at the plasma centre. They analyze soft X‑ray (3–10 keV) data to assess impurity dynamics at the plasma core. Impurity concentration at the core is disrupted by kink and disruptive instabilities, which can further degrade the plasma’s thermal insulation and stability.
The authors discuss the possible consequences of the presence of multiply charged impurities in a tokamak plasma. The first such consequence is cooling of the plasma column periphery due to line radiation, which may lead to a sharpening of the electrical conductivity profile σ(r) and hence of the current density profile j(r), as is observed at high values of ne. Concentration of highly ionized impurities towards the plasma column axis is a possible competing process, leading to flattening of σ(r) and j(r) or even to a skin effect. From the results of soft (3–10 keV) X-radiation measurements the authors derive conclusions about the behaviour of impurities at the centre of the plasma. They find that the concentration of impurities can be interrupted by the development of plasma instabilities – especially kink and "disruptive" instabilities. With increasing ne, Te and discharge duration, the role of impurities in the shaping of j(r) necessarily increases. At some level, this may cause an additional deterioration in the thermal insulation and stability of the plasma column.
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Drift Instability Due to Impurity Ions
B. Coppi, H. P. Furth, M. N. Rosenbluth et al. · Physical Review Letters · 1966 · 109 citations
Rotation and Structure of Low-Frequency Oscillations inside the ST-Tokamak Plasma
J. Hosea, F. C. Jobes, R. L. Hickok et al. · Physical Review Letters · 1973 · 92 citations
The runaway electron discharge regime in the Tokamak-6 device
V. S. Vlasenkov, V. M. Leonov, V. G. Merezhkin et al. · Nuclear Fusion · 1973 · 84 citations