Density profile reconstruction using HIBP in ECRH plasmas in the TJ-II stellarator

Abstract

A: Heavy Ion Beam Probing (HIBP) is a unique tool for plasma potential measurements. In the TJ-II stellarator (CIEMAT, Madrid, Spain) HIBP is capable to move the sample volume (SV) from Low Field Side (LFS) of a plasma column through the plasma center to High Field Side (HFS), so the time evolution of plasma potential ϕ and secondary beam total current I tot radial profiles can be obtained during one shot. I tot is proportional to the plasma density n e at the SV, it is affected by attenuation factors along the beam trajectory. The work shows the method for the n e radial profile reconstruction from HIBP I tot signal. Using the method, for the first time n e radial profiles are reconstructed from HIBP I tot signal in TJ-II regimes with electron cyclotron resonance heating (ECRH) and the line-averaged electron density ne up to 0.8 • 10 19 m −3 . Reconstructed n e (ρ) profiles are consistent with Thomson scattering data.

Topology of 2D turbulent structures based on intermittence in the TJ-II stellarator

“…The energy of the secondary ions provides information about the plasma potential Φ in the sample volume of the ion beam, the beam current I tot provides information about the local electron density n e , and the toroidal displacement of the beam Z c provides information about the poloidal current density in the plasma. Traveling through the plasma, the beam experiences attenuation, affecting I tot [20].…”

Heavy Ion Beam Probing Conceptual Design for The Globus-M2 Tokamak

“…HIBP has been successfully implemented on many fusion devices, both stellarators (LHD, TJ-II, CHS, Uragan-2M) and tokamaks (TEXT, T-10, JIPPTII-U, ISTOK). On TJ-II stellarator HIBP was successfully used for Alfven eigen modes studies [6,7], on T-10 tokamak it was used for studies of Geodesic Acoustic Modes (GAM) [8], on stellarators CHS and TJ-II it was also used for the electron density profile measurements [9,10].…”