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Plasma turbulence and MHD instabilities in the ohmic L-mode and bias h -mode regimes of the Tcabr Tokamak

Grant number: 13/20652-2
Support type:Research Grants - Visiting Researcher Grant - International
Duration: December 01, 2013 - November 30, 2014
Field of knowledge:Physical Sciences and Mathematics - Physics
Principal Investigator:Ivan Cunha Nascimento
Grantee:Ivan Cunha Nascimento
Visiting researcher: Yurii Kuznetsov
Visiting researcher institution: Kharkov Institute of Physics and Technology (KIPT), Ukraine
Home Institution: Instituto de Física (IF). Universidade de São Paulo (USP). São Paulo , SP, Brazil
Associated research grant:11/50773-0 - Center of excellence in physics and applications of plasmas, AP.TEM

Abstract

Plasma turbulence and MHD instabilities in the Ohmic L-mode and Bias H -mode regimes of the TCABR tokamakRESUMEPlasma Turbulence and H-mode are main lines of research in the TCABR tokamak and many new results were already obtained and published. The first objective of this project is to install a system of feedback control of the plasma current to improve the reproducibility of the discharges. Using discharges with reproducible plasma current and also diagnostics recently installed, among others, arrays of bolometer (24 channels) and soft X-rays (20 channels) detectors, microwave reflectometer and Thomson scattering systems, allied to a powerful system of multi-Langmuir-probes and fast signal digitalizers, the investigations will be continued with reproducible biasing L-H transitions with and without strong MHD activity and control of discharge parameters avoiding disruptions. The synchronization of frequencies of MHD oscillations with those of sawtooth oscillations, radiation detected by the bolometer and Halpha line emission arrays will be investigated to determine the underlying conditions responsible for this phenomenon. Geodesic Acoustic Modes will continue to be investigated to understand the TCABR results which compared to theoretical results appear at higher frequencies. Destruction of the ETB (Edge Transport Barrier) in the presence of MHD activity, detected in the previous works, will be also investigated taking into account the possible effects of impurities. Gundestrup and/or Mach probes will be constructed and used to measure edge plasma rotation to complement spectrometer measurements presently under execution on the TCABR tokamak. (AU)