Microscopic structure of plasma turbulence in the torsatron TJ-K
Plasma turbulence is characterised by the fluctuation of density, potential and temperature on all temporal and spatial scales. In magnetically confined plasmas, turbulence causes an increased particle and heat transport across the magnetic field lines. The focus of this work is the experimental investigation of density and potential fluctuations and the resulting turbulent transport. A poloidal Langmuir probe array with 64 tips is employed to investigate turbulence in the confinement region at all spatial scales. A dependence on the drift scale rho_s is found. The cross phase between density and potential fluctuations is near zero, indicating drift wave turbulence. This result is also found in simulations. Finally, the conditional averaging method was used to detect the spatio-temporal structure of turbulent events with simple two probe measurements. The results are in agreement with the results from the probe array.