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Radiation transport simulations of the deuterium Lyman line series using EIRENE predict a factor of 2 increase of Balmer-α emission in the JET-ILW low confinement divertor plasmas in high-recycling and detached conditions caused by the re-absorption of Lyman-β emission. The photon tracing model in the EIRENE code is applied to SOLPS-ITER pure deuterium plasma solutions of JET-ILW to evaluate the contribution of Lyman-β capture towards the population density of D(p=3) and, consequently, the Balmer-α emission. The local population escape factors of Lyman-α and Lyman-β lines in the JET-ILW divertor show steep spatial gradients and indicate local regions with high opacity in high-recycling and detached conditions. The relative contribution of Lyman-β capture towards the population density of D(p=3) is significant in high-recycling and detached conditions. This observation is further corroborated by line-integrated calculations using Balmer-α diagnostic line-of-sights.

Electromagnetic wave data measured by the low-altitude Detection of Electro-Magnetic Emissions Transmitted from Earthquake Regions (DEMETER) spacecraft sometimes exhibit intense emissions at discrete, harmonically spaced frequencies. We present a comprehensive analysis of this type of phenomenon, and we demonstrate that it is caused by very low frequency (VLF) transmitters in Europe. All available data were investigated for a possible presence of the events. Altogether, 87 events were identified, occurring exclusively during the nighttime. The occurrence of the events does not show any clear relation to the A E and D s t geomagnetic activity indices. The events are clearly localized, occurring either close to Great Britain or in the vicinity of its geomagnetically conjugated region. The frequency spectra of the events typically consist of up to four spectral peaks at multiples of about 1.3 kHz. Additional weaker spectral peaks at frequencies of about 1.9 kHz and 3.2 kHz are occasionally present. The events observed in the Northern Hemisphere tend to have larger-frequency bandwidths than the events observed in the Southern Hemisphere. The occurrence of these events is correlated with the simultaneous detection of signals from VLF transmitters. A bicoherence analysis is employed to demonstrate that wave-wave coupling takes place. Finally, it is shown that the occurrence of the events is associated with a significantly increased precipitation of energetic electrons in a wide range of energies. [ABSTRACT FROM AUTHOR]

In this paper we present some investigations of the broadening mechanisms affecting the emission line profiles of impurities present in the divertor regions of tokamaks. For that purpose, we have considered two visible lines (C IV n = 5-6 and n = 6-7) emitted by lithium-like carbon ions for which the contributions of the Zeeman, Stark and Doppler effects are examined. The paper is focused on the impact of differing electron and ion temperatures on the broadening and shapes of the C IV n = 6-7 line for conditions relevant to a detached tokamak divertor plasma. It is shown, that the C IV n = 6-7 line profile calculated with differing electron and ion temperatures may be significantly different from the one calculated with equal temperatures but the same density. This suggests that the electron density determination from the fit of the measured spectra of such a line may be inaccurate when using equal ion and electron temperatures instead of differing ones. (© 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [ABSTRACT FROM AUTHOR]

Abstract: A soft X-ray pulse height analyzer has been designed and installed on the J-TEXT tokamak for measuring the electron temperature and possibly for monitoring the impurity content and concentration. A multi-channel analyzer, a set of amplifiers, and three silicon drift detectors constitute the detection system. An off-line analysis code was developed to analyze the raw data recorded by the system. The system can measure a minimum electron temperature of 400eV, and its routine operation provides electron temperature measurements at three different positions with a temporal resolution of 60ms and channel separation of 18cm. Line radiation from some moderate and high Z impurities are observable by the system. The results show that the intensity of line radiation from heavy impurity ions is inversely proportional to the plasma density under similar discharge conditions. [Copyright &y& Elsevier]

The International Electrotechnical Commission Standard 61482-1 describes procedures for measuring the thermal performance of fabrics and garments intended for use in clothing for workers exposed to electric arcs. This paper demonstrates that the tests in this Standard fail to produce controlled laboratory conditions. The dominant magnetic and thermal buoyancy forces have been minimized leaving two undefined and uncontrolled forces to randomly dominate arc motion, plasma flow, and thermal stress. The tests also produce hazards significantly different from those faced by victims in real situations. The velocity of the plasma impinging on a victim is incorrect. The color of the radiation is incorrect. The molten metal droplets impinging on the victim are incorrect. The tests only consider clothing stretched over a surface, whereas loose and unbacked cloth suffers considerably more stress. In order to emulate real arcing faults, it will be necessary to use parallel copper and aluminum electrodes. In addition, for personnel working on high-voltage, a “pop-out” test needs to be developed because a fault current that starts by entering and exiting the body becomes an arc inside the clothing. [ABSTRACT FROM PUBLISHER]