Using laser induced fluorescence and passive spectroscopy on a magnetically confined low-temperature plasma, anomalous ion heating is observed which exceeds collisional heating from the electrons by a factor of up to five. Direct wave heating due to the 2.45 GHz microwave as well as stochastic heating by large-amplitude fluctuations could be ruled out as explanations. Good quantitative agreement is found when comparing the missing power in the ion species with heating power due to the dissipation of drift-wave turbulence. This turbulent energy transfer into the ion channel could have important consequences for the interpretation of transport in fusion plasmas.

Analyses of non-linear interactions in drift-wave turbulence were carried out in wavenumber space on experimental data obtained from multi-probe measurements in the toroidally confined plasma of the stellarator TJ-K. Recent results are reported. The inverse cascade of energy from small to large scales as typical for two-dimensional turbulence is verified. The transfer in k space is found to be governed by non-local processes. The same way, large-scale zonal flows (ZFs) are found to tap energy from small-scale turbulence, as consistent with the vortex-thinning mechanism. An enhancement of the correlation between ZF shear and Reynolds stress as a source of ZF energy is observed, when strong background shear flows are imposed, which comes along with increased long-range correlations.

Soliton generation mechanism in a double-plasma device is explored by carrying out diagnostics measurements using a Langmuir probe and laser induced fluorescence. Soliton profiles are investigated for different amplitudes, durations and frequencies of the applied grid signal. Particle-in-cell simulations are also carried out in order to study in detail the evolution and propagation mechanism of solitons. For low temperature ions, the simulation results show similar features as observed in the experiment. However, the simulations with fast ions having larger velocities than the soliton show strong interaction of the fast ions with the soliton and ion burst, producing another soliton through the energy exchange mechanism.

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