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| 2. |
- Sharapov, S.E., et al.
(författare)
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Energetic particle instabilities in fusion plasmas
- 2013
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Ingår i: Nuclear Fusion. - : IOP Publishing. - 1741-4326 .- 0029-5515. ; 53:10, s. 104022-
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Tidskriftsartikel (refereegranskat)abstract
- Remarkable progress has been made in diagnosing energetic particle instabilities on present-day machines and in establishing a theoretical framework for describing them. This overview describes the much improved diagnostics of Alfvén instabilities and modelling tools developed world-wide, and discusses progress in interpreting the observed phenomena. A multi-machine comparison is presented giving information on the performance of both diagnostics and modelling tools for different plasma conditions outlining expectations for ITER based on our present knowledge.
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| 4. |
- Gassner, T., et al.
(författare)
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Deuterium beam acceleration with 3rd harmonic ion cyclotron resonance heating in Joint European Torus : Sawtooth stabilization and Alfven eigenmodes
- 2012
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Ingår i: Physics of Plasmas. - : AIP Publishing. - 1070-664X .- 1089-7674. ; 19:3, s. 032115-
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Tidskriftsartikel (refereegranskat)abstract
- Experiments on accelerating NBI-produced deuterium (D) beam ions from their injection energy of similar to 110 keV up to the MeV energy range with 3rd harmonic ion cyclotron resonance heating were performed on the Joint European Torus [P. H. Rebut and B. E. Keen, Fusion Technol. 11, 13 (1987)]. A renewed set of nuclear diagnostics was used for analysing fast D ions during sawtooth stabilization, monster sawtooth crashes, and during excitation of Alfven eigenmodes (AEs) residing inside the q = 1 radius. The measurements and modeling of the fast ions with the nonlinear HAGIS code [S. D. Pinches et al., Comput. Phys. Commun. 111, 133 (1998)] show that monster sawtooth crashes are strongly facilitated by the AE-induced re-distribution of the fast D ions from inside the q = 1 radius to the plasma edge. [http://dx.doi.org/10.1063/1.3696858]
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| 5. |
- Kiptily, V. G., et al.
(författare)
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On a fusion born triton effect in JET deuterium discharges with H-minority ion cyclotron range of frequencies heating
- 2019
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Ingår i: Nuclear Fusion. - : IOP PUBLISHING LTD. - 0029-5515 .- 1741-4326. ; 59:6
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Tidskriftsartikel (refereegranskat)abstract
- An effect due to fusion born triton production has been observed in JET high-performance deuterium plasma discharges with neutral beam injection (NBI) and H-minority ion cyclotron range of frequencies (ICRF) heating, using DD and deuterium tritium (DT) neutron spectrometry as well as fusion product loss measurements. The observations show that a decrease of the second harmonic omega = 2 omega(cD) enhancement of the DD neutron rate correlates with an increase of the triton burnup rate. An acceleration of tritons due to absorbing ICRH power at the third harmonic omega = 3 omega(cT) has been observed. This effect could indicate a redistribution of ICRH power absorption at omega approximate to omega(cH) = 2 omega(cD) = 3 omega(cT) with increasing triton concentration at the ion cyclotron resonance layer. Also, the reduction of the second harmonic enhancement of the DD neutron rate can be caused by burning of the accelerated deuterium as the tritium concentration grows. This is an extremely non-linear process as both mechanisms intensify with triton concentration. It determines the necessity to consider the ICRH power absorption omega = 3 omega(cT) in modelling of high-performance deuterium discharges with simultaneous NBI and H-minority ICRF heating as well as the assessment of enhanced burnup of ICRF accelerated deuterium for the development of high-performance plasma scenarios and DT fusion rate predictions.
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| 8. |
- Yavorskij, V., et al.
(författare)
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Results of Predictive Fokker-Planck Modelling of NBI Deuterons in ITER
- 2011
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Ingår i: Journal of fusion energy. - : Springer Science and Business Media LLC. - 0164-0313 .- 1572-9591. ; 30:4, s. 307-322
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Tidskriftsartikel (refereegranskat)abstract
- First an analytical formalism is presented for calculating the source distribution of ions generated by neutral beam injection (NBI) in tokamak plasmas. A general NBI ion source term, applicable to studies in the phase space up to 6 dimensions, is provided for neutral beams with finite thickness and divergence. Further, using this source term for the envisaged NBI in ITER, we carry out 3D Fokker-Planck modelling of the steady-state deuteron distribution function of NBI produced fast deuterons relaxing on bulk plasma components. For two basic ITER scenarios we demonstrate the poloidal profiles of the beam deuteron density, of the NBI generated current as well as of the NBI power deposition to bulk electrons and ions. Further, we evaluate the capability of gamma and NPA diagnostics of NBI ions in ITER and demonstrate the sensitivity of the distributions of NBI generated ions to different ITER operation scenarios.
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| 9. |
- Yavorskij, V., et al.
(författare)
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TF ripple effects on the NBI deuteron confinement in JET
- 2007
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Ingår i: 34th EPS Conference on Plasma Physics 2007, EPS 2007 - Europhysics Conference Abstracts. - 9781622763344 ; , s. 876-879
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Konferensbidrag (refereegranskat)abstract
- Ripple induced reduction of the fluxes of deuterium neutrals in the 5-40 keV energy range from the plasma mid-plane was observed in recent JET experiments. The maximum observed reduction of D0 fluxes due to ripple is approximately 50 % and occurs at energies above 30 keV. In positive shear plasmas without ICRH ripple reduction of D0 fluxes vanishes at energies below 10 keV. However, in the case of plasmas with low or reversed shear core, increased D0 fluxes were observed for energies below 10-20 keV in the presence of additional ripple and ICRH heating. Interpretive modeling of the deuterium neutral emission that accounts for the superbanana ripple diffusion of NBI ions is in reasonable agreement with measurements at least for the scenarios without ICRH. Note that ripples may essentially effect the fast ion confinement in ITER where TF ripple magnitude at the outer separatrix is expected to be δ ∼ 0.5%.
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