Edge plasma conditions and plasma-surface interactions in Extrap T1

Bergsåker, H.; Møller, Anders Hauer; Li, G.X.; Hellblom, G.; Brzozowski, J.; Emmoth, B.; Gudowska, Irena

doi:10.1016/0022-3115(94)00571-0

Cited by 6 publications

(7 citation statements)

References 8 publications

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“…The hot electron flow is highly directional, in the electron drift direction (which is opposite to the magnetic field). The asymmetry in the hot electron flux is larger than the asymmetry in the total time-integrated heat flux reported in [1], which is also shown for comparison.…”

Section: Asymmetry Of the Hot Electron Fluxsupporting

confidence: 49%

“…The magnetic fluctuation level was about 1%. Non-time-resolved edge heat flux measurements have previously been made with a thermocouple-based calorimeter [1]. These measurements gave the radial and The measurements with the target probe and analysis of the data can be divided into four areas.…”

Section: Measurements On the T1 Rfpmentioning

confidence: 99%

“…The presence of an energetic component in the electron velocity distribution is generally observed in the edge of reversed-field pinch (RFP) experiments. Such observations are based on heat flux measurements [1][2][3][4][5][6][7][8][9], measurements using an electron energy analyser (EEA) [10][11][12][13] or by viewing the x-rays from a target which is inserted into the plasma [14][15][16]. The source of the energetic electrons in the edge region is believed to be associated with stochastic radial transport from the hot central region caused by fluctuations (b r ) of the radial component of the field relative to the equilibrium field [17].…”

Section: Introductionmentioning

confidence: 99%

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Measurements of hot electrons in the Extrap T1 reversed-field pinch

Welander

Bergsåker

1998

Plasma Phys. Control. Fusion

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The presence of an anisotropic energetic electron population in the edge region is a characteristic feature of reversed-field pinch (RFP) plasmas. In the Extrap T1 RFP, the anisotropic, parallel heat flux in the edge region measured by calorimetry was typically several hundred MW m −2 . To gain more insight into the origin of the hot electron component and to achieve time resolution of the hot electron flow during the discharge, a target probe with a soft x-ray monitor was designed, calibrated and implemented. The x-ray emission from the target was measured with a surface barrier detector covered with a set of different x-ray filters to achieve energy resolution. A calibration in the range 0.5-2 keV electron energy was performed on the same target and detector assembly using a LaB 6 cathode electron gun. The calibration data are interpolated and extrapolated numerically. A directional asymmetry of more than a factor of 100 for the higher energy electrons is observed. The hot electrons are estimated to constitute 10% of the total electron density at the edge and their energy distribution is approximated by a half-Maxwellian with a temperature slightly higher than the central electron temperature. Scalings with plasma current, as well as correlations with local Hα measurements and radial dependences, are presented.

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Section: Asymmetry Of the Hot Electron Fluxsupporting

confidence: 49%

Section: Measurements On the T1 Rfpmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Measurements of hot electrons in the Extrap T1 reversed-field pinch

Welander

Bergsåker

1998

Plasma Phys. Control. Fusion

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“…It has to be mentioned that in RFPs the footprint of PWI also shows a poloidal asymmetry between ion and electron drifts, with electron and ion flows separately intercepted by the wall, due to the surface distortion [366,367,577,578]. An example is shown in figure 68.…”

Section: Effect Of Magnetic Topology On Plasma-wall Interactionmentioning

confidence: 99%

“…In devices with carbon wall as RFX or RFX-mod, the value of plasma density is determined by wall desorption rather than by the fuelling rate. In fact graphite is shot by shot saturated with trapped hydrogen/deuterium, so that the plasma density after the breakdown is completely sustained by atoms released by the wall, with a recycling coefficient R which can be greater than 1 [211,578]. The number of released particles depends both on the number of atoms stored in the graphite and on the power load on the wall, which makes density control very difficult, especially at high current.…”

Section: Recycling Controlmentioning

confidence: 99%

The reversed field pinch

et al. 2021

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This paper reviews the research on the reversed field pinch (RFP) in the last three decades. Substantial experimental and theoretical progress and transformational changes have been achieved since the last review (Bodin 1990 Nucl. Fusion 30 1717–37). The experiments have been performed in devices with different sizes and capabilities. The largest are RFX-mod in Padova (Italy) and MST in Madison (USA). The experimental community includes also EXTRAP-T2R in Sweden, RELAX in Japan and KTX in China. Impressive improvements in the performance are the result of exploration of two lines: the high current operation (up to 2 MA) with the spontaneous occurrence of helical equilibria with good magnetic flux surfaces and the active control of the current profile. A crucial ingredient for the advancements obtained in the experiments has been the development of state-of-art active feedback control systems allowing the control of MHD instabilities in presence of a thin shell. The balance between achievements and still open issues leads us to the conclusion that the RFP can be a valuable and diverse contributor in the quest for fusion electricity.

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Magnetic Confinement Fusion—Experimental Physics: Reversed Field Pinches

Zuin¹

2021

Encyclopedia of Nuclear Energy

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Edge plasma conditions and plasma-surface interactions in Extrap T1

Cited by 6 publications

References 8 publications

Measurements of hot electrons in the Extrap T1 reversed-field pinch

Measurements of hot electrons in the Extrap T1 reversed-field pinch

The reversed field pinch

Magnetic Confinement Fusion—Experimental Physics: Reversed Field Pinches

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