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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 (

This work estimates the degree of turbulent intermittence of the plasma potential measured by a Heavy Ion Beam Probe in the core plasma region of the TJ-II stellarator. It is shown that the intermittence varies in a significant way with the plasma state (ion or electron root). In addition, radial minima of the intermittence are found to be associated with the location of topological structures of the flow associated with some important low-order rational surfaces. The local pressure gradient was also estimated, and a clear correlation was found between the steepening of the pressure gradient and the deepening of the minima of the intermittence, suggesting that the minima are associated with pressure gradient driven modes. By estimating the rotation velocity of the plasma from the measured plasma potential, it was possible to make a rough reconstruction of the twodimensional radial-poloidal map of intermittence, thus clarifying the topological structure of the intermittence. The experimental results were put into context by comparing with simulations performed using a resistive Magneto-Hydrodynamic turbulence model.

2D poloidal contour plots of plasma potential, plasma density, and their fluctuations have been measured in low density plasmas sustained by Electron Cyclotron Resonance Heating using a heavy ion beam probe (HIBP) system in the TJ-II stellarator. A HIBP has been used in the new energy scanning mode to obtain the measurements for a 2D poloidal cross section of the stellarator. The 2D map for the absolute plasma potential shows a local maximum in the plasma core as expected in low density plasma scenarios. Fluctuations in the HIBP secondary ion current, as a proxy of plasma density fluctuations, appear both in positive and negative density gradient regions, with a normalized level of density fluctuations higher in the negative density gradient region. The TJ-II innovative experimental setup developed using a dual HIBP diagnostic paves the way for model validation on core plasma potential asymmetries and particle transport and fluctuations under positive and negative density gradient scenarios.

The conceptual design of the heavy ion beam probe (HIBP) for T-15MD tokamak (R = 1.5 m, a = 0.67 m, Bt = 2 T, Ipl = 2 MA) is presented. The location of the HIBP injection and detection points is chosen based on the probing beam trajectory calculations. Observation area covers the whole radial interval 0 < r < a for Bt = 1 T, Ipl = 1 MA with the beam energy Eb

The upgraded Heavy Ion Beam Probe (HIBP) diagnostics on the T-10 tokamak (National Research Center 'Kurchatov Institute') is presented. HIBP is a powerful tool to study electric potential in the core and edge plasmas along with broadband turbulence and quasicoherent modes such as Geodesic Acoustic Mode (GAM) and Alfven Eigenmode (AE). To study broadband turbulence and AEs, which can be driven by fast electrons in regimes with auxiliary Electron Cyclotron Resonance Heating the frequency range of about several hundred kHz is needed. The upgrade is focused on the extension of the frequency range of HIBP signals up to 500 kHz, and on increasing of density operating limit up to 5-1019 m-3. It becomes possible due to a newly designed emitter-extractor unit of HIBP accelerator aiming to provide the primary beam with the current of 300 pA at the energy of 300 keV and diameter of 7-10 mm. The new in-vessel elements of a primary beamline - wire sensor and Faraday cup - were upgraded accordingly to be able to deliver the probing beam with advanced parameters to the plasma.

Alfvén eigenmodes (AEs) were studied in low magnetic shear flexible heliac TJ-II (B 0 = 0.95 T, R 0 = 1.5 m, 〈 a 〉 = 0.22 m) neutral beam injection (NBI) heated plasmas (P NBI ⩽ 1.1 MW, E NBI = 32 keV) using the heavy ion beam probe (HIBP). L-mode hydrogen plasmas heated with co-, counter- and balanced-NBI and electron cyclotron resonance heating (ECRH) were investigated in various magnetic configurations with rotational transform ι(a)/2π = 1/q ~ 1.5–1.6. The HIBP diagnostic is capable of simultaneously measuring the oscillations of the plasma electric potential, density and poloidal magnetic field. In earlier studies chirping modes have been observed with 250 kHz f AE n ¯ e = (0.3–1.5) × 1019 m−3. In this paper we report the observation of chirping modes obtained with NBI only in plasmas with densities similar to those of earlier studies and obtained after lithium evaporation in the vacuum vessel. The absence of ECRH in the discharges studied here shows that ECRH is not a necessary ingredient to obtain chirping modes in TJ-II but rather a tool for obtaining low-density discharges. Using the HIBP we deduce that the location of the AE chirping mode is −0.8 ρ B pol perturbations are nearly symmetric for both ECRH + NBI and NBI-only plasmas. On TJ-II, the dominant effect on the nonlinear evolution of the AE from the chirping state to the steady-frequency state is the magnetic configuration, determined by the vacuum ι and plasma current I pl.