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The European power system faces two main challenges: first, the increasing share of fluctuating energy sources in the power generation sector challenges the balance of generation and demand. Second, the expected shift towards using more electricity in the heating and transportation sectors leads to rising demand. To ensure both sufficient energy supply and long-term power system stability of the power system, fusion power is expected to play an important role in the future. This paper provides a sensitivity analysis of fusion power plant parameters in a power system with a large fraction of renewable energies. The results depend strongly on the underlying scenario assumptions, especially on future technical and economic improvements. Finally, the amount of fusion power investments depends on both demand level and relative costs of competing technologies.

We present discretisation schemes for the heat diffusion equation in strongly magnetised plasmas in 2-d Cartesian and 3-d cylindrical geometry. The algorithms described do not use field-aligned coordinates, but show, nevertheless, a strong reduction of the pollution of perpendicular heat flux caused by parallel heat conduction, compared to standard finite element or other finite difference formulations. Results for test examples show independence of the numerical error from @g"@? for values of @g"@?/@g"@? up to 10^9 in plane and 10^1^2 in periodic cylinder geometry (simulating toroidal connection). The algorithms appear particularly well suited for dynamic MHD calculations, where the effort of using exactly aligned coordinates becomes prohibitive.

In addition to the Greenwald density limit and the threshold conditions for H-mode access, neoclassical tearing modes (NTMs) pose the most severe constraint to tokamak operation in discharges with conventional (monotonic) current density profiles. We show, at hand of the example of ASDEX Upgrade the resulting constraints on density and useful heating power. At high densities, collisionality effects can lead to the appearance of a second stable regime for NTMs. A further limitation can arise from the appearance of fishbone instabilities which, depending on the orientation of the injected beams, can also lead to a clamping of the total plasma energy content. The resulting diagram is also useful as a guide for a strategy to expand the operating range by feedback stabilisation of the neoclassical tearing modes and for the orientation of the beamlines.

Modulated Electron Cyclotron Resonance Heating was applied in ASDEX Upgrade to study the electron heat diffusivity χ e . Its dependence on the isotope mass was found to be opposite to that one known from the power balance analysis. Off-axis ECRH deposition leads to a reduced electron heat transport in the centre which cannot be explained by an inward heat pinch. Electron Cyclotron Current Drive was applied to completely stabilise a (3/2)-neoclassical tearing mode with a consequent recovery of the plasma energy. High electron and ion temperatures have been simultaneously achieved by application of central counter ECCD in a discharge with an internal ion transport barrier.

A many particle approach to spectral line shapes has been generalized including the influence of a uniform magnetic field. Within this approach the electrons are treated fully quantum mechanically. Ion dynamics have been included via the well-known model microfield method. The developed theory has been applied to calculate the first Balmer lines of hydrogen for plasma parameters as can be found in dense divertor plasmas. It has been shown that the half-width, e.g., of the Hβ line is a useful tool for the determination of the electron densities in such plasmas.