Tungsten radiation from tokamak-produced plasmas

Isler, R.C.; Neidigh, R.V.; Cowan, Robert D.

doi:10.1016/0375-9601(77)90908-2

Cited by 114 publications

(62 citation statements)

References 1 publication

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“…4. A smaller broad peak structure appearing around 6 nm region is quite noticeable, which are also observed in other experiments in fusion plasmas [5,31,32]. Furthermore, Berlin EBIT group also observed similar unknown broad structure around 6 nm at electron beam energies corresponding to ionization energy of open 4f tungsten ions [33].…”

Section: Analysessupporting

confidence: 79%

Measurement of EUV Spectra from High Z Elements in the Large Helical Device

Suzuki¹,

Katō²,

Sakaue³

et al. 2011

AIP Conference Proceedings

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Abstract. Extreme ultra-violet (EUV) emission spectra from highly charged tin, xenon and tungsten ions have been measured in optically thin high-temperature plasmas produced in the Large Helical Device (LHD) at the National Institute for Fusion Science by using a grazing incidence spectrometer and a tracer-encapsulated solid pellet (TESPEL) injector. Quasi-continuous spectral features arising from unresolved transition array (UTA) of open 4d subshell ions were commonly observed for tin, xenon and tungsten around 13.5, 11, and 5 nm, respectively, when edge plasma was cooled enough. The spectral appearance obviously depends on edge electron temperature and atomic number. In the case of intermediate edge temperature, sharp discrete lines from highly charged open 4s or 4p subshell ions are clearly observed for tin and xenon in longer wavelength side of the UTAs but not for tungsten. Assignments of the strong discrete lines have been performed with the help of comparisons with the other experimental data and the theoretical calculations by Cowan code. Contribution of open 4f subshell ions should also be considered to interpret the whole spectra from tungsten ions.

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Section: Analysessupporting

confidence: 79%

Measurement of EUV Spectra from High Z Elements in the Large Helical Device

Suzuki¹,

Katō²,

Sakaue³

et al. 2011

AIP Conference Proceedings

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“…However, when the W concentration exceeds a certian level in the central part of the plasma the radiative losses limit the plasma operation and performance such that for ITER the central concentration lower than several # $ " % ' & is obligatory [3]. This has been found earlier in the ORMAK [4] and PLT [5] tokamaks in which the central W radiation prevented fusion relevant plasma operation due to W concentrations in the range of # $ ( % 0 ) . Due to the use of a divertor and other operational precautions the W concentration can be controlled to low enough values [6] and fusion relevant operation is possible as demonstrated at ASDEX Upgrade [7,8].…”

Section: Introductionmentioning

confidence: 99%

Calculation and experimental test of the cooling factor of tungsten

Pütterich¹,

Neu²,

Dux³

et al. 2010

Nucl. Fusion

209

196

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Abstract. The cooling factor of W is evaluated using state of the art data for line radiation and an ionization balance which has been benchmarked with experiment. For the calculation of line radiation, level-resolved calculations were performed with the Cowan code to obtain the electronic structure and excitation cross sections (plane-wave Born approximation). The data were processed by a collisional radiative model to obtain electron density dependent emissions. These data were then combined with the radiative power derived from recombination rates and Bremsstrahlung to obtain the total cooling factor. The effect of uncertainties in the recombination rates on the cooling factor were studied and were identified to be of secondary importance. The new cooling factor is benchmarked, by comparisons of the line radiation to spectral measurements as well as to a direct measurement of the cooling factor. Additionally, a less detailed calculation using a configuration averaged model was performed. It was used to benchmark the level-resolved calculations and to improve the prediction on radiation power from line radiation for ionization stages which are computationally challenging. The obtained values for the cooling factor validate older predictions from literature. Its ingredients and the absolute value are consistent with the existing experimental results regarding the value itself, the spectral distibution of emissions and the ionization equilibrium. A table of the cooling factor versus electron temperature is provided. Finally, the cooling factor is used to investigate the operational window of a fusion reactor with W as intrinsic impurity. The minimum value of ¤ ¦ ¥ § © , for which a thermonuclear burn is possible, is increased by 20% for a W concentration of " !

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“…The emission of the W quasicontinuum from tokamak plasma was observed there for the first time [68]. Heating by NB counter injection always provoked major disruptions within 30-50 ms.…”

Section: Early Devices With High-z Pfcsmentioning

confidence: 81%

High-Z plasma facing components in fusion devices: boundary conditions and operational experiences

Neu

2006

Phys. Scr.

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In present day fusion devices optimization of the performance and experimental freedom motivates the use of low-Z plasma facing materials. However in a future fusion reactor, for economic reasons a sufficient lifetime of the first wall components is essential. Additionally, tritium retention has to be small to meet safety requirements. Tungsten appears to be the most realistic material choice for reactor plasma facing components (PFCs) because it exhibits the lowest erosion. But besides this there are a lot of criteria which has to be fulfilled simultaineously in a reactor. Results from present day devices and from laboratory experiments confirm the advantages of high-Z PFM but also point to operational restrictions, when using them as PFCs. They are associated with the central impurity concentration, which is determined by the sputtering yield, the penetration of the impurities and their transport within the confined plasma. The restrictions could exclude successful operation of a reactor, but concomitantly there exist remedies to ameliorate their impact. Obviously some price has to be paid in terms of reduced performance but lacking of materials or concepts which could substitute high-Z PFCs, emphasis has to be put on the development and optimization of reactor relevant scenarios which incorporate the experiences and measures.

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Tungsten radiation from tokamak-produced plasmas

Cited by 114 publications

References 1 publication

Measurement of EUV Spectra from High Z Elements in the Large Helical Device

Measurement of EUV Spectra from High Z Elements in the Large Helical Device

Calculation and experimental test of the cooling factor of tungsten

High-Z plasma facing components in fusion devices: boundary conditions and operational experiences

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