| 1. |
- Hellesen, Carl, 1980-, et al.
(författare)
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Neutron emission generated by fast deuterons accelerated with ion cyclotron heating at JET
- 2010
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Ingår i: Nuclear Fusion. - : IOP Publishing. - 0029-5515 .- 1741-4326. ; 50:2
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Tidskriftsartikel (refereegranskat)abstract
- For the first time, the neutron emission from JET plasmas heated with combined deuterium neutral beam injection and third harmonic ion cyclotron radio frequency heating have been studied with neutron emission spectroscopy (NES). Very high DD neutron rates were observed with only modest external heating powers, which was attributed to acceleration of deuterium beam ions to energies of about 2-3 MeV, where the DD reactivity is on a par of that of the DT reaction. Fast deuterium energy distributions were derived from analysis of NES data and confirm acceleration of deuterium beam ions up to energies around 3 MeV, in agreement with theoretical predictions. The high neutron rates allowed for observations of changes in the fast deuterium populations on a time scale of 50 ms. Correlations were seen between fast deuterium ions at different energies and magnetohydrodynamic activities, such as monster sawtooth crashes and toroidal Alfven eigenmodes.
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| 2. |
- Hellesen, Carl, 1980-, et al.
(författare)
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Measurements of fast ions and their interactions with MHD activity using neutron emission spectroscopy
- 2010
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Ingår i: Nuclear Fusion. - : IOP Publishing. - 0029-5515 .- 1741-4326. ; 50:8, s. 084006-
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Tidskriftsartikel (refereegranskat)abstract
- Ion cyclotron radio frequency (ICRF) heating can produce fast ion populations with energies reaching up to several megaelectronvolts. Here, we present unique measurements of fast ion distributions from an experiment with 3rd harmonic ICRF heating on deuterium beams using neutron emission spectroscopy (NES). From the experiment, very high DD neutron rates were observed, using only modest external heating powers. This was attributed to acceleration of deuterium beam ions to energies up to about 2-3 MeV, where the DD reactivity is on a par with that of the DT reaction. The high neutron rates allowed for observations of changes in the fast deuterium energy distribution on a time scale of 50 ms. Clear correlations were seen between fast deuterium ions in different energy ranges and magnetohydrodynamic activities, such as monster sawteeth and toroidal Alfven eigen modes (TAE). Specifically, NES data showed that the number of deuterons in the region between 1 and 1.5 MeV were decaying significantly during strong TAE activity, while ions with lower energies around 500 keV were not affected. This was attributed to resonances with the TAE modes.
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| 3. |
- Kiptily, V., et al.
(författare)
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Doppler broadening of gamma ray lines and fast ion distribution in JET plasmas
- 2010
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Ingår i: Nuclear Fusion. - : IOP Publishing. - 0029-5515 .- 1741-4326. ; 50:8, s. 084001-
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Tidskriftsartikel (refereegranskat)abstract
- The Doppler broadening of individual γ-ray lines was measured with a high purity germanium detector in JET plasma experiments. High-resolution γ-ray spectrometry of nuclear reactions between energetic D, 3 He and 4 He ions accelerated by ion cyclotron resonance heating and main plasma impurities such as carbon and beryllium has been used. The nuclear reactions giving rise to γ-rays have been identified and an effective temperature of the heated ions has been obtained in JET discharges. This technique could be used for fast ion and fusion alpha-particle studies in ITER.
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| 4. |
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| 5. |
- Nocente, M., et al.
(författare)
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High-resolution gamma ray spectroscopy measurements of the fast ion energy distribution in JET He-4 plasmas
- 2012
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Ingår i: Nuclear Fusion. - : IOP Publishing. - 0029-5515 .- 1741-4326. ; 52:6, s. 063009-
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Tidskriftsartikel (refereegranskat)abstract
- High-resolution gamma-ray measurements were carried out on the Joint European Torus (JET) in an experiment aimed at accelerating He-4 ions in the MeV range by coupling third harmonic radio frequency heating to an injected He-4 beam. For the first time, Doppler broadening of gamma-ray peaks from the C-12(d, p gamma)C-13 and Be-9(alpha, n gamma)C-12 reactions was observed and interpreted with dedicated Monte Carlo codes based on the detailed nuclear physics of the processes. Information on the confined He-4 and deuteron energy distribution was inferred, and confined He-4 ions with energies as high as 6 MeV were assessed. A signature of MHD activity in gamma-ray traces was also detected. The reported results have a bearing on diagnostics for fast ions in the MeV range in next step fusion devices.
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