Turbulence and transport in the scrape-off layer TCABR tokamak

Abstract

We study the scrape-off layer turbulence and transport in Tokamak Chauffage Alfvén Brésilien (TCABR) before and during the launching of radio frequency excited waves that interact with the boundary plasma. We present the main characteristics of the background electrostatic fluctuations and the intermittent bursts. During the perturbation, the plasma turbulence intensity increases and the average phase velocity reverses its direction. The total turbulence driven transport and the transport radially convected by the intermittent fluctuation bursts also increase with the perturbation. The probability distributions of the bursts have long tails, resembling those typical of flight distributions with a decay parameter increasing with the wave excitation.

Multifractality in plasma edge electrostatic turbulence

“…The measurements were performed at a sampling frequency of 1 MHz, and the measuring circuit has a 300 kHz bandwidth to avoid aliasing, such that in every discharge up to 10 5 points can be recorded. 12,21 Figure 1 shows the typical time evolution of a plasma discharge in TCABR. The plasma current Fig.…”

Recurrence quantification analysis of turbulent fluctuations in the plasma edge of Tokamak Chauffage Alfvén Brésilien tokamak

“…Two of these probes measure the floating potential fluctuations and the third probe measures the ion saturation current fluctuations. 21 The whole set was mounted at the outer equatorial region of the tokamak ͓Fig. 1͑a͔͒.…”

“…Probes have been built in TCABR to measure the electrostatic potential and ion saturation current fluctuations in the edge region, giving information on plasma potential and particle density. 21 Electrostatic fluctuations in the plasma edge have been assigned to physical processes governed by nonlinear mechanisms, such as the interaction between drift waves, which appear due to the steep density gradients in the tokamak edge region. 1,22,23 These interactions exhibit a strong dependence on the radial variable, which is reflected in the turbulent fluctuation levels measured in the experiments.…”

Kinetic Particle Simulation Study of Parallel Heat Transport in Scrape-off Layer Plasmas over a Wide Range of Collisionalities

“…Using an Eulerian code with Fokker-Planck collision operator, the bulk population was shown to have a double-lobed shape [20], which has not been reproduced with either PARASOL-1D [18] or BIT1 [19]. However, experimental results cannot resolve this conflict because they are not sensitive enough to differentiate the tail [21].…”