Electromagnetic turbulent structures: A ubiquitous feature of the edge region of toroidal plasma configurations

Spolaore, M.; Vianello, N.; Furno, I.; Carralero, D.; Agostini, M.; Alonso, A.; Avino, Fabio; Cavazzana, R.; Masi, G.; Fasoli, A.; Hidalgo, C.; Martines, E.; Momo, B.; Scaggion, A.; Scarin, P.; Spagnolo, S.; Spizzo, G.; Theiler, C.; Zuin, M.

doi:10.1063/1.4906869

Cited by 20 publications

(31 citation statements)

References 56 publications

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“…These observations confirm also the electromagnetic (EM) features of the observed structures as expected for ELMs [23]. In particular they are current filaments as observed in the ELM structures in the COMPASS experiment [24], and for turbulence filaments as well [25,22]. Bursty behavior of ω t (t) and δJ t , correlated with D α peaks, are observed in the Fig.…”

Section: Transient Events During H-modesupporting

confidence: 84%

“…In the ω t (t) evident negative peaks are observed indicating that these structures are vortices, rotating in the cross-field plane. Similar feature was observed in the turbulent filaments in the edge region of all magnetic configuration fusion devices as well as in linear devices [21,22]. D α correlated bursty spreading is also observed in the δJ t spectrogram (fig 7), corresponding to the bipolar peaks observed in the δJ t (t) evolution, left panel.…”

Section: Transient Events During H-modesupporting

confidence: 77%

“…This difference can be due to the different local velocity shear that was found to be effective in the vorticity selection [22,26].…”

mentioning

confidence: 99%

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H-mode achievement and edge features in RFX-mod tokamak operation

Spolaore¹,

Cavazzana²,

Marrelli³

et al. 2017

Nucl. Fusion

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The RFX-Mod experiment is a fusion device designed to operate as a Reversed Field Pinch (RFP), with a major radius R " 2 m and a minor radius a " 0.459 m. Its high versatility recently allowed operating also as an ohmic tokamak allowing comparative studies between the two configurations in the same device. The device is equipped with a state of the art MHD mode feedback control system, providing a magnetic boundary effective control and modulation, by applying resonant or nonresonant magnetic perturbations (MP) both in RFP and in tokamak configurations. In the fusion community the application of MPs is widely studied as a promising tool in particular to limit the impact of plasma filaments and ELMs, in particular on plasma facing components. An important issue is envisaged in the exploitation of the RFX-Mod active control system for ELM mitigation studies.As a first step in this direction, this paper will focus on the most recent achievements in term of RFX-Mod tokamak explored scenarios, which allowed the first investigation of the ohmic and edge biasing induced H-mode. In particular the realization of D-shaped tokamak discharges and the design and deployment of an insertable polarized electrode were accomplished. Both operations took advantage of the implementation of a real-time feedback control system of the electron density and of a multivariable shape feedback control system designed on a full modelbased approach. Indications of Ohmic H-mode were transiently observed during Single Null shaped plasmas. Stationary H-mode phases were instead obtained with insertable electrode biasing stimulation. The edge biasing is applied in new operation scenarios relatively unexplored with this technique in particular in plasma shaped Single Null discharges and in the very low-q circular plasma discharges, qpaq ă 2, achievable in RFX-Mod. Important modification of the edge plasma density and flow properties are observed as well as, in some cases, a complex "dithering" phenomenology, characterized by very fast L-H and H-L transitions. These strong fluctuations appear associated to the onset of MHD activity, whose behaviour will be analyzed and discussed in the paper along with the filamentary structures observed in the fast turbulence electromagnetic fluctuations.Published as a journal article in Nuclear Fusion http://iopscience.iop.org/article/Abstract The RFX-mod experiment is a fusion device designed to operate as a Reversed Field Pinch (RFP), with a major radius R= 2 m and a minor radius a = 0.459 m. Its high versatility recently allowed operating also as an ohmic tokamak allowing comparative studies between the two configurations in the same device. The device is equipped with a state of the art MHD mode feedback control system, providing a magnetic boundary effective control, by applying resonant or non-resonant magnetic perturbations (MP) both in RFP and in tokamak configurations. In the fusion community the application of MPs is widely studied as a promising tool to limit the impact of plasma filaments and ELMs on p...

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Section: Transient Events During H-modesupporting

confidence: 84%

Section: Transient Events During H-modesupporting

confidence: 77%

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H-mode achievement and edge features in RFX-mod tokamak operation

Spolaore¹,

Cavazzana²,

Marrelli³

et al. 2017

Nucl. Fusion

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“…This method represents a simplified 2D version of the one adopted in the Cluster mission for the measurement of currents in the magnetosphere [13] and it was applied for the first time in a fusion experiment in RFX-mod, with a probe head combining magnetic and electrostatic pins [7]. By using the analogous diagnostic concept the estimate of the current density associated to turbulent filaments was estimated and compared in different experiments including RFX-mod in Reversed Field Pinch as well as in tokamak configuration, in Torpex device, in the stellarator TJ-II [14] and also in COMPASS tokamak [15], where a direct estimate of current density inside ELMs was provided [16].…”

Section: Conceptual Designmentioning

confidence: 99%

Design of a High Resolution Probe Head for Electromagnetic Turbulence Investigations in W7-X

Agostinetti¹,

Spolaore²,

Brombin³

et al. 2018

IEEE Trans. Plasma Sci.

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An insertable probe head called High Resolution Probe (HRP) has been developed at Consorzio RFX in the framework of the EUROfusion S1 work program and in collaboration with IPP Greifswald, to study the electrostatic and electromagnetic features of turbulence in the edge region of Wendelstein 7-X using the Multi-Purpose Manipulator (MPM). The paper reports the design development of the HRP diagnostic head, from the choice of the sensors to the engineering design. The assumptions and evaluations supporting the main design choices, together with the R&D tests carried out to check the most critical parts, are described in detail.Index Terms-insertable probe, electromagnetic fluctuations, stellarator, W7-X

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“…This kind of signal was also obtained in ref. [71], where measurements of the coherent structure temperature were presented using the triple probe technique and erroneously analyzed as a real temperature fall in the coherent structure.…”

Section: Coherent Structures Radial Propagationmentioning

confidence: 99%

Flutuações turbulentas de temperatura no Tokamak TCABR

Baquero¹

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Electromagnetic turbulent structures: A ubiquitous feature of the edge region of toroidal plasma configurations

Cited by 20 publications

References 56 publications

H-mode achievement and edge features in RFX-mod tokamak operation

H-mode achievement and edge features in RFX-mod tokamak operation

Design of a High Resolution Probe Head for Electromagnetic Turbulence Investigations in W7-X

Flutuações turbulentas de temperatura no Tokamak TCABR

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