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Focuses on the conceptual design of a heavy ion beam probe (HIBP) diagnostics for the International Thermonuclear Experimental Reactor, which is intended for measurements of plasma potential profile in a gradient area. Principles of HIBP measurements; Optimization of the probing scheme; Comparison of the energy range; Bending electric field estimations.

Advanced heavy ion beam probe (HIBP) operates on the T-10 tokamak with 20–130 μ A T l + beam accelerated up to 330 keV. The HIBP has a unique capability to measure the mean value of the core plasma potential, and the oscillations in potential φ , density n e and poloidal magnetic field simultaneously in 5 spatially separated sample volumes for OH and ECRH plasmas with n ¯ e = (0.3 − 5) × 1 0 19 m − 3 , 100 < I p l < 330 kA. Time evolution of local plasma parameters and/or radial profiles can be measured in a single shot. The profile in the range 0.25 < ρ < 1 is available shot by shot for B 0 < 2.2 T. The paper describes main elements of hardware: injector, beamlines, control systems, analyzer, power supplies, and software for HIBP. Physical examples show that HIBP can measure the cross-phase of density oscillations, the poloidal phase velocity of turbulence rotation, the poloidal electric field and the radial turbulent particle flux. Spectral analysis allows us to distinguish various types of turbulence, such as broadband (<500 kHz), quasicoherent, tearing and geodesic acoustic modes. [ABSTRACT FROM AUTHOR]

In this paper, we analyze the impact of electron cyclotron resonance heating and electron cyclotron current drive on the Alfvénic instabilities driven by neutral beam injection observed in the TJ-II stellarator. An MHD stability analysis of driven Alfvén eigenmodes compatible with the experimental plasma parameters is carried out in order to compare with the data provided by magnetic coils, radiation monitors, and heavy ion beam probes. To this end, the vacuum magnetic configuration modified by the different levels of plasma current, the thermal plasma parameters and the fast ion pressure profiles generated by the co-injected neutral beam, are entered in the FAR3d gyro-fluid code in order to follow the linear evolution of the destabilized plasma equilibrium. Linear growth rates and radial location of the dominant predicted modes coincident in frequency with the observed fluctuations are presented. Despite the uncertainties related to the estimation of the rotational transform profile, the code predictions agree within reasonable accuracy with the experimental results. [ABSTRACT FROM AUTHOR]

Kurchatov Institute is upgrading now the T-15 tokamak to the machine with D-shaped plasma and copper magnetic system, capable for realizing lower and upper single-null and double-null magnetic configurations. The heating and current drive (CD) system consisting of the neutral beam injection (NBI), electron cyclotron resonance heating (ECRH/CD), electron Bernstein waves (EBW) heating and CD, ion cyclotron resonance heating (ICRH/CD), helicon and Lower Hybrid (LH) waves heating and CD is aiming to provide an effective heating of both electrons and ions, and on- and off-axis CD. The main research topics foreseen are the features of the confinement at high magnetic field and low aspect ratio, Advanced Tokamak regimes, steady-state operation, effects of turbulence with an emphasis on the role of the radial electric field E r , Geodesic Acoustic Modes (GAM) and Zonal Flows (ZF) in transport and confinement (including plasma self-organization, profile resiliency, influence of the q -profile), investigations of MHD effects and disruptions, Alfvén Eigenmodes (AE) and fast particles. Extended set of advanced diagnostics with identical equipment located at two toroidal positions will contribute to the 3D reconstruction of various types of the plasma structures like quasicoherent modes and long-range correlations. [ABSTRACT FROM AUTHOR]

A new set of Heavy Ion Beam Probe diagnostic (HIBP-2) was recently installed in the TJ-II stellarator. HIBP-2 is being operated simultaneously with the previously existing HIBP-1 to provide the coherence data analysis aiming for the 3D studies of the Long-Range Correlations and Alfvenic Eigenmodes. A new Control and Data Acquisition System (CDAS) of high performance and high reliability has been made to operate HIBP-2. The CDAS of HIBP-1 is being upgraded to a similar configuration. The distributed architecture implementing a client–server model provides flexibility and system scalability. The developed CDAS has shown reliable operation of dual HIBP. This paper describes the CDAS of this dual diagnostics. [ABSTRACT FROM AUTHOR]