| 1. |
- Solano, E. R., et al.
(författare)
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ELMS and strike point jumps
- 2005
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Ingår i: Journal of Nuclear Materials. - : Elsevier BV. - 0022-3115 .- 1873-4820. ; 337-39:03-jan, s. 747-750
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Tidskriftsartikel (refereegranskat)abstract
- If an ELM is a peeling of flux surfaces from the plasma, due to a broken separatrix, current density is lost as well as particles and energy. The fast loss of a current-carrying plasma layer modifies the plasma equilibrium, leading to sudden shifts in the strike points at each ELM, towards the plasma centre. An experimental study of this conjectured model of the ELM has been made at JET, showing that in all cases of Type I ELMs studied, strike point shifts were observed. In two cases studied in detail, the estimated equilibrium changes provoked by flux surface peeling agree qualitatively with the observed strike point shifts.
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| 2. |
- Solano, E. R., et al.
(författare)
-
ELMs and strike point movements
- 2008
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Ingår i: Nuclear Fusion. - : IOP Publishing. - 0029-5515 .- 1741-4326. ; 48:6
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Tidskriftsartikel (refereegranskat)abstract
- A detailed study of position changes of plasma strike points before and after edge localized modes (ELMs) in JET was carried out. A hypothesis being tested is that in an ELM previously closed edge field lines would open up, releasing plasma current and leading to the formation of a new, smaller separatrix. It was observed that after each ELM strike points have shifted a few centimetres towards the plasma centre ( up in JET). In some cases a transient (< 100 mu s), upwards large (> 10 cm) jump of strike positions was observed first. It was followed by an equally fast jump down to the shifted strike positions. Such behaviour has not been described in previous computational models of the ELM. Therefore two novel instability mechanisms are presented, which contribute to explain the changes in strike point position: an X-point instability, due to positive toroidal current density at the X-point, and a diamagnetic instability, due to negative inboard toroidal current density.
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| 3. |
- Vecchio, A., et al.
(författare)
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Synthesis of helicopters noise for sound quality analysis
- 2007
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Ingår i: 13th AIAA/CEAS Aeroacoustics Conference (28th AIAA Aeroacoustics Conference). - 9781624100031
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Konferensbidrag (refereegranskat)abstract
- This paper presents a model-based sound synthesis approach for flyover and interior noise of aircraft, with special focus on helicopters. The research is aimed at the development of technology and tools to support a more environmental friendly design of modern helicopters thus facilitate a better exploitation of helicopters in regional transportation. The synthesis of helicopter noise is based on a Sound Quality Equivalent model that is extracted from sound recordings. A thorough noise analysis allows identifying and extracting the most relevant noise components. The sound synthesis model is then implemented as compact and sound quality accurate model consisting of a superimposition of rpm dependant tonal components, one third octave noise bands to characterize the broadband noise and interference pattern. The noise feature extraction process from recorded data and the sound synthesis are illustrated. The resulting noise models are validated for a number of typical helicopter sounds. The potential for using this technology approach to target sound design is briefly discussed.
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