Extreme ultraviolet spectroscopy and modeling of Cu on the SSPX Spheromak and laser plasma “Sparky”

Weller, M. E.; Safronova, A.S.; Clementson, J.; Kantsyrev, V.L.; Safronova, U. I.; Beiersdörfer, P.; Petkov, E.E.; Wilcox, P. G.; Osborne, G. C.

doi:10.1063/1.4727916

Cited by 2 publications

(1 citation statement)

References 15 publications

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“…It has been shown that oxygen is a very good indicator of temperature, and, in some cases, the impurities are desired. 21,22 From a non-LTE model in Ref. 22, it was shown that the relative intensity of the FIG.…”

Section: B Euv Emission and Plasma Formationmentioning

confidence: 98%

Study of instability formation and EUV emission in thin liners driven with a compact 250 kA, 150 ns linear transformer driver

et al. 2014

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A compact linear transformer driver, capable of producing 250 kA in 150 ns, was used to study instability formation on the surface of thin liners. In the experiments, two different materials, Cu and Ni, were used to study the effect of the liner's resistivity on formation and evolution of the instabilities. The dimensions of the liners used were 7 mm height, 1 mm radius, and 3 lm thickness. Laser probing and time resolved extreme ultraviolet (EUV) imaging were implemented to diagnose instability formation and growth. Time-integrated EUV spectroscopy was used to study plasma temperature and density. A constant expansion rate for the liners was observed, with similar values for both materials. Noticeable differences were found between the Cu and Ni instability growth rates. The most significant perturbation in Cu rapidly grows and saturates reaching a limiting wavelength of the order of the liner radius, while the most significant wavelength in Ni increases slowly before saturating, also at a wavelength close to the liner radius. Evidence suggests that the instability observed is the well-known m ¼ 0 MHD instability. However, upon comparing the instability evolution of Cu and Ni, the importance of the resistivity on the seeding mechanism becomes evident. A comparison of end-on and side-on EUV emission possible indicates the formation of precursor plasma, where it has been estimated using EUV spectroscopy that the precursor plasma temperature is approximately 40 eV with ion density of order 10 19 cm À3 , for both materials. V C 2014 AIP Publishing LLC. [http://dx.

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Section: B Euv Emission and Plasma Formationmentioning

confidence: 98%

Study of instability formation and EUV emission in thin liners driven with a compact 250 kA, 150 ns linear transformer driver

et al. 2014

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Three new extreme ultraviolet spectrometers on NSTX-U for impurity monitoring

Weller

Beiersdörfer

Soukhanovskii

et al. 2016

Review of Scientific Instruments

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Three extreme ultraviolet (EUV) spectrometers have been mounted on the National Spherical Torus Experiment-Upgrade (NSTX-U). All three are flat-field grazing-incidence spectrometers and are dubbed X-ray and Extreme Ultraviolet Spectrometer (XEUS, 8-70 Å), Long-Wavelength Extreme Ultraviolet Spectrometer (LoWEUS, 190-440 Å), and Metal Monitor and Lithium Spectrometer Assembly (MonaLisa, 50-220 Å). XEUS and LoWEUS were previously implemented on NSTX to monitor impurities from low- to high-Z sources and to study impurity transport while MonaLisa is new and provides the system increased spectral coverage. The spectrometers will also be a critical diagnostic on the planned laser blow-off system for NSTX-U, which will be used for impurity edge and core ion transport studies, edge-transport code development, and benchmarking atomic physics codes.

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Extreme ultraviolet spectroscopy and modeling of Cu on the SSPX Spheromak and laser plasma “Sparky”

Cited by 2 publications

References 15 publications

Study of instability formation and EUV emission in thin liners driven with a compact 250 kA, 150 ns linear transformer driver

Study of instability formation and EUV emission in thin liners driven with a compact 250 kA, 150 ns linear transformer driver

Three new extreme ultraviolet spectrometers on NSTX-U for impurity monitoring

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