Plasma interaction with tungsten samples in the COMPASS tokamak in ohmic ELMy H-modes

Dimitrova, M.; Weinzettl, V.; Matějíček, Jiří; Popov, Tsv.; Marinov, S; Costea, S.; Dejarnac, R.; Ştöckel, J.; Havlíček, Jan; Pánek, R.

doi:10.1088/1742-6596/700/1/012008

Cited by 5 publications

(3 citation statements)

References 8 publications

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“…In the experiments described here, the probes are swept by a triangular voltage at a frequency of 1 kHz, so that one IV is recorded for 0.5 ms. This time is shorter than the duration of the inter-ELMs period [33,34]. In addition, during the ELMs spikes, the plasma is not in a steady-state -even if the probes are swept quickly, one cannot estimate correctly the plasma potential and the electron temperature and density.…”

Section: Resultsmentioning

confidence: 99%

Advantages of the first-derivative probe technique over the three- and four-parameter probe techniques in fusion plasmas diagnostics

et al. 2018

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In this work, the advantages are presented and discussed of the first-derivative probe technique over the three- and the four-parameter conventional probe techniques for diagnostics of fusion plasmas. The conventional probe techniques for estimation of the plasma potential and the electron temperature and density can only be used when the electron energy distribution function (EEDF) is Maxwellian. The first-derivative probe technique can provide reliable results for the plasma potential and the real EEDF when the latter deviates from Maxwellian. To exemplify the application of the results obtained by different techniques, results on the parallel power-flux density distribution in the divertor region of the COMPASS tokamak, IPP.CR, are presented and discussed.

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Section: Resultsmentioning

confidence: 99%

Advantages of the first-derivative probe technique over the three- and four-parameter probe techniques in fusion plasmas diagnostics

et al. 2018

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“…The data illustrated in figure 8(b) show that in H-mode operation of COMPASS, using the FDPT yields a Maxwellian EEDF (black and red circles in figure 8(b)) [39]. During an L-mode, the EEDF can deviate from the Maxwellian and can be approximated by a bi-Maxwellian EEDF-additional groups of cold electrons appear denoted in figure 8(b) by triangles; the thermal electrons are indicated by squares.…”

Section: Measurements In the Compass Tokamak Divertor Plasmamentioning

confidence: 99%

Application of the triple-probe technique to magnetized plasmas

Dimitrova¹,

Popov²,

Dejarnac³

et al. 2022

Plasma Phys. Control. Fusion

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The triple-probe technique is a diagnostic widely used to determine the electron temperature in various devices and plasma conditions. It was developed for measurements in low-pressure gas-discharge plasmas in the absence of a magnetic field. This paper presents a comparison of the experimental results obtained by swept Langmuir probe measurements with those obtained by the triple-probe technique in magnetized plasmas in three experimental machines with different magnetic field magnitudes (0.01-1.15 T). The reliability of the triple-probe results for the electron temperature in tokamak plasmas at higher magnetic fields is discussed. It was found that the larger the magnetic field, the more the triple-probe technique overestimates the electron temperature compared with single swept Langmuir probes. The explanation proposed in this paper is based on a shift in the floating potential towards the plasma potential in the presence of a magnetic field, yielding a more positive voltage measured by the triple-probe technique and therefore higher electron temperatures. Using the extended formula for the electron probe current in the presence of a magnetic field a correction factor is derived such that the triple-probe technique yields a temperature similar to that of the swept Langmuir probe techniques.

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“…The scanning power supply will be applied to the electronic circuit of the EMPA electrostatic probe array to obtain its current-voltage characteristic, and more effort will be taken to study the EMPA electrostatic probe data and to derive the T e and n e information in the experiments. The ELM and disruption characteristics will be studied with EMPAmeasured ion saturation currents and floating potentials in the future experiments [58,59]. Deeper analysis of the EMPA data already measured in the EAST experiments will be conducted, e.g., deriving the fine structure of current filaments with the EMPA data, and studying the detailed characteristics of Alfvén eigenmodes and high frequency pedestal fluctuations in EAST plasmas.…”

Section: Discussionmentioning

confidence: 99%

A new electromagnetic probe array diagnostic for analyzing electrostatic and magnetic fluctuations in EAST plasmas

Lan

Shi

Yan

et al. 2023

Plasma Sci. Technol.

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A novel electro-magnetic probe array (EMPA) diagnostic which consists of a magnetic probe array and an electrostatic probe array has been developed on EAST recently. The EMPA is fixed near the first wall at horizontal port P. The magnetic probe array of the EMPA consists of 24 same magnetic probes, and each of them can measure toroidal, poloidal and radial magnetic fluctuations simultaneously which provides additional toroidal magnetic fluctuation measurements comparing with the regular magnetic probes on EAST. With higher sampling rate of 2 MHz, the EMPA magnetic probes can provide higher frequency magnetic fluctuation measurements. The magnetic probe array of the EMPA is arranged by 2 parallel layers of magnetic probes with radial distance of 63 mm. And each layer of the magnetic probes is arranged in 4 poloidal rows and 3 toroidal columns. The compact arrangement of the EMPA magnetic probe array largely improve the toroidal mode number measurement ability from -8≤n≤8 to -112≤n≤112, and also improve the high poloidal wave number measurement ability of magnetic fluctuations comparing with the regular high frequency magnetic probes on EAST. The electrostatic probe array of the EMPA consists of 2 sets of four-tip probes and a single-tip probe array with 3 poloidal rows and 4 toroidal columns. It complements the electrostatic parameter measurements behind the main limiter and near the first wall in EAST. The engineering details of the EMPA diagnostic including the mechanical system, electrical system, acquisition and control system, and effective area calibration are presented. The preliminary applications of the EMPA in L-mode and H-mode discharges on EAST have demonstrated that the EMPA works well for providing the information of the magnetic and electrostatic fluctuations and can contribute to deeper physical analysis in future EAST experiments.

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Plasma interaction with tungsten samples in the COMPASS tokamak in ohmic ELMy H-modes

Cited by 5 publications

References 8 publications

Advantages of the first-derivative probe technique over the three- and four-parameter probe techniques in fusion plasmas diagnostics

Advantages of the first-derivative probe technique over the three- and four-parameter probe techniques in fusion plasmas diagnostics

Application of the triple-probe technique to magnetized plasmas

A new electromagnetic probe array diagnostic for analyzing electrostatic and magnetic fluctuations in EAST plasmas

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