Plasma potential and turbulence dynamics in toroidal devices (survey of T-10 and TJ-II experiments)

Melnikov, A. V.; Hidalgo, C.; Eliseev, L.G.; Ascasíbar, E.; Chmyga, A. A.; Dyabilin, K. S.; Krasilnikov, I.A.; Krupin, V.A.; Krupnik, L. I.; Khrebtov, S. M.; Komarov, A. D.; Kozachek, A.S.; López‐Bruna, D.; Лысенко, С. Е.; Mavrin, V.A.; Pablos, J.L. de; Pastor, I.; Perfilov, S.V.; Pedrosa, M. A.; Shurygin, R. V.; Vershkov, V.A.; Team, Tj‐Ii

doi:10.1088/0029-5515/51/8/083043

Cited by 57 publications

(52 citation statements)

References 42 publications

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“…The main features of the potential profiles behavior show quite satisfactory agreement with experimental one [9][10][11].…”

Section: Neoclassical Modeling Of the Electric Potential Profilessupporting

confidence: 79%

“…The HIBP was used in the T-10 circular tokamak [4], in TJ-II, a four-period flexible heliac with helical plasma axis [5] and in the stellarators CHS [6] and LHD [7] to study the potential with high spatial (< 1 cm) and temporal (1 µs) resolution in plasmas with comparable parameters, but in different magnetic configurations. Comparison for Ohmic (OH) and Electron Cyclotron Resonance Heating (ECRH) plasmas in the two machines, T-10 and TJ-II reveals similar tendencies of the potential profiles [8,9]. The paper reports the results of the comparative studies of plasma potential in all four machines, including CHS and LHD with the same diagnostics.…”

Section: Introductionmentioning

confidence: 99%

“…The paper reports the results of the comparative studies of plasma potential in all four machines, including CHS and LHD with the same diagnostics. Although the HIBP was used during scans in the main plasma parameters on T-10, TJ-II, CHS and LHD [9][10][11][12], and all data obtained in this way were considered in this study. This paper shows only the results obtained on a limited number of interesting discharges in four machines, illustrating our main conclusions.…”

Section: Introductionmentioning

confidence: 99%

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Plasma Potential in Toroidal Devices: T-10, TJ-II, CHS and LHD

Melnikov

Hidalgo²,

Ido

et al. 2012

Plasma and Fusion Research

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Direct measurements of the electric potential ϕ, using the Heavy Ion Beam Probing, have been undertaken in the T-10 tokamak, and in the helical devices with various magnetic topology: TJ-II, CHS and LHD. L-mode plasmas were considered. Despite the large differences in machine sizes, heating methods and the topology of the magnetic field, the observed ϕ shows the striking similarities: (i) Similar magnitudes of E r ; (ii) For low densities, n e < 0.5 × 10 19 m −3 , ϕ is positive, and an increase in n e is associated with the decrease of positive ϕ and formation of a negative E r ; (iii) For higher densities, n e > (0.5-1) × 10 19 m −3 , both ϕ and E r tends to be negative despite the use of different heating methods: Ohmic and ECR heating in T-10, ECRH and/or NBI in TJ-II, CHS and LHD; (iv) Application of ECRH, causing a rise in T e , results in more positive values for ϕ and E r . The analysis show that the main features of the ϕ dependences on the n e and T e agree with neoclassical predictions on the four devices within experimental and simulation precisions.

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“…The main features of the potential profiles behavior show quite satisfactory agreement with experimental one [9][10][11].…”

Section: Neoclassical Modeling Of the Electric Potential Profilessupporting

confidence: 79%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Plasma Potential in Toroidal Devices: T-10, TJ-II, CHS and LHD

Melnikov

Hidalgo²,

Ido

et al. 2012

Plasma and Fusion Research

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“…Poloidal rotation, as deduced from the two-point correlation technique, is directed to ion diamagnetic drift with values in the order of 4 km/s. In the pure NBI stage (t = 1110-1160 ms) of discharge (P NBI = 0.58 MW) the plasma density increases, plasma potential and electric field become negative [8,9]. In these conditions poloidal velocity changes the direction from ion to electron diamagnetic drift with values up to 10 km/s, which is consistent with previous results using Doppler reflectometry [10].…”

Section: Radial Scan Measurementssupporting

confidence: 90%

Two Point Correlation Technique for the Measurements of Poloidal Plasma Rotation by Heavy Ion Beam Probe

Eliseev

Melnikov

Perfilov

et al. 2012

Plasma and Fusion Research

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The paper proposes a method to measure poloidal rotation velocity of toroidal plasma v pol using Heavy Ion Beam Probe (HIBP) with a multi-slit energy analyzer. The method is based on calculation of phase shift between broadband density turbulence measured simultaneously in two sample volumes, located at the same magnetic surface but separated poloidally. Oscillatory component of HIBP beam current is used as a density turbulence characteristic. HIBP is capable to provide the temporal evolution of the v pol in a fixed radial position and also the v pol profile by periodic radial scan. Method was verified in real plasma experiment in ECRH and NBI discharges on the TJ-II stellarator. Result shows that in low density discharges (n e ≈ 0.3-0.5 × 10 19 m −3 ) absolute values of local v pol is about 4-6 km/s, oriented in the ion diamagnetic drift direction. When HIBP operates for radial scans, it is conventionally measuring the plasma potential profile, and so provides the radial electric field E r and velocity of E × B drift (v E×B ) at the same time as plasma rotation. Experimental data shows that in low density ECRH plasma the rotation velocity coincides with E × B velocity within achieved experimental accuracy. When the density is increasing, both v E×B and v pol tends to decrease and then change the sign at threshold plasma densities in the range of n e ≈ 0.7-1 × 10 19 m −3 . With this new proposed technique HIBP becomes the new effective tool to study plasma rotation and turbulence characteristics in toroidal plasmas.

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“…In this regard the Heavy Ion Beam Diagnostic (HIBD) is a powerful tool that can in principle provide the local measurement of the quantities of interest being these the electron density and temperature, the internal poloidal field and the plasma potential with spatial resolution of several mm and down to the micro second range temporal resolution. For instance, experiments in ISTTOK [2][3][4] [5], TJ-II [6], T-10 [6] and in the LHD device [7] have all together demonstrated the capabilities of the HIBD in plasma density, potential fluctuations and mean potential measurements, supporting MHD and turbulence analysis including Alfvèn Eigenmodes (TJ-II) [8] and Geodesic Acoustic modes (T-10) [9] studies.…”

Section: Introductionmentioning

confidence: 91%

Retrieving Models For Localised Measurements By Heavy Ion Beam Diagnostic

Malaquias¹,

Henriques²,

Nedzeskiy³

2016

Proceedings of 1st EPS Conference on Plasma Diagnostics — PoS(ECPD2015)

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We report here on the recent developments in the deconvolution of the path integral effects for the study of MHD pressure-like fluctuations measured by Heavy Ion Beam Diagnostic. In particular, we develop improved methods to account for and remove the path integral effect on the determination of the ionization generation factors, including the double ionization of the primary beam. We test the method using the HIBD simulation code which computes the real beam trajectories and attenuations due to electron impact ionization for any selected synthetic profiles of plasma current, plasma potencial, electron temperature and density. Simulations have shown the numerical method to be highly effective in ISTTOK within an overall accuracy of a few percent (< 3%). The method here presented can effectively reduce the path integral effects and may serve as the basis to develop improved retrieving techniques for plasma devices working even in higher density ranges. As a test example an m=1 (100 kHz) MHD mode spatial profile evolution is retrieved with excellent accuracy after the reduction of path integral effects. The 2D MHD mode-like structure is reconstructed by means of a spatial projection of all 1D measurements obtained during one full rotation of the mode.

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Plasma potential and turbulence dynamics in toroidal devices (survey of T-10 and TJ-II experiments)

Cited by 57 publications

References 42 publications

Plasma Potential in Toroidal Devices: T-10, TJ-II, CHS and LHD

Plasma Potential in Toroidal Devices: T-10, TJ-II, CHS and LHD

Two Point Correlation Technique for the Measurements of Poloidal Plasma Rotation by Heavy Ion Beam Probe

Retrieving Models For Localised Measurements By Heavy Ion Beam Diagnostic

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