| 1. |
- Askinazi, L. G., et al.
(författare)
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Evolution of geodesic acoustic mode in ohmic H-mode in TUMAN-3M tokamak
- 2012
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Ingår i: Technical physics letters. - 1063-7850 .- 1090-6533. ; 38:3, s. 268-271
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Tidskriftsartikel (refereegranskat)abstract
- The behavior of a geodesic acoustic mode (GAM) in the TUMAN-3M tokamak has been experimentally studied using the heavy-ion beam probing technique. Oscillations of the electric potential under the action of a GAM localized at the plasma periphery have been detected. The GAM was observed in the regime of low confinement (L-mode) with low plasma density (similar to 0.8 x 10(19) m(-3)) and disappeared upon the transition to a high confinement regime (H-mode). The possible role of GAM as a precursor of the improved confinement (LH-transition) is discussed.
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| 2. |
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| 3. |
- Askinazi, L. G., et al.
(författare)
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Plasma potential evolution in various operational modes in the TUMAN-3M tokamak
- 2007
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Ingår i: 34th EPS Conference on Plasma Physics 2007, EPS 2007 - Europhysics Conference Abstracts. - 9781622763344 ; , s. 2010-2013
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Konferensbidrag (refereegranskat)abstract
- In a scenario with Counter-NBI it was found using HIBP that, due to the NBI effect (most probably, orbit loss with some heating and momentum impact), core plasma potential plasma gradually became more negative (for ∼200V). Strong positive perturbation of the core plasma potential was registered by the HIBP during the burst of peripheral MHDs with low m, n. If such a burst takes place in the H-mode (both ohmic and counter-NBI heated), the positive potential perturbation leads to H-mode termination. The most probable mechanism of the positive field build-up during MHD burst is though to be a loss of fast electrons along partly disturbed magnetic field lines near the island's separatrix [3,4]. This mechanism is similar to the ergodic divertor's action on the TEXTOR [6], where radial electric field modification by the electron loses was also discussed. A quantitative analysis of the subject may be found in [7]. Similar mechanism may be responsible for a positive perturbation of central plasma potential registered in the sawtooth crashes. The GAM with δφ/φ∼0.3 and δφ/φ≫δn/n∼0.05 where observed with HIBP in a core region of the TUMAN-3M r/a∼0.33 in the current ramp phase. Further studies are needed to reveal a possible connection between the GAM evolution and plasma confinement in the TUMAN-3M.
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| 4. |
- Askinazi, L. G., et al.
(författare)
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Radial electric field evolution in various operational modes in the TUMAN-3M tokamak
- 2008
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Ingår i: Journal of Physics, Conference Series. - : IOP Publishing. - 1742-6588 .- 1742-6596. ; 123, s. 012010-
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Tidskriftsartikel (refereegranskat)abstract
- Radial electric field evolution has been studied on the TUAMN-3M tokamak in different modes of operation: ohmic and NBI heating, L- and H-modes, with and without strong MHD activity. Peripheral radial electric field was measured using Langmuire probes, which were inserted up to 2cm inside LCFS, while core plasma potential evolution was measured using HIBP diagnostic. It was found, that in presence of strong MHD activity radial electric field in a vicinity of the island changed sign from negative to positive and could reach up to 4kV/m. Central plasma potential exhibited a positive perturbation of ∼700V during the MHD burst. This positive radial electric field might lead to H-mode termination, both in ohmic and NBI heating cases. Possible mechanism of the positive Er generation, namely the electron losses along ergodized magnetic field lines in the presence of MHD-island, is discussed. The same mechanism might be responsible for the positive potential spikes during a saw-tooth crash, also observed using HIBP. Another phenomenon observed using HIBP was quasi-coherent potential oscillations with the frequency close to one of the GAM. Possible location of these oscillations in the core region r/a ∼ 0.33 is discussed.
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| 5. |
- Iiyoshi, A., et al.
(författare)
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Muon catalyzed fusion, present and future
- 2019
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Ingår i: Proceedings of the international conference on advances and applications in plasma physics (aapp 2019). - : American Institute of Physics (AIP). - 9780735419261
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Konferensbidrag (refereegranskat)abstract
- The novel proposal of the Muon Catalyzed Fusion (MCF) concept is brought to light employing recent results on its relevant cross sections. In 1993, Kino et al. proposed an innovative scheme of MCF, employing non-adiabatic calculations of muonic atom-nucleus collision in the energy range from 10-3 eV to 100 eV, whereby the fusion in flight along with the formation of muonic molecular resonances was revisited [1]. In 1994, Froelich independently calculated the cross section up to 2 keV, and found the behavior of like resonance [2]. In 1996, Kino et al. examined these resonances, and concluded that the resonances were not suitable for MCF [3]. As a result, the research has been continued to examine the possibility of non-resonant In-flight Muon Catalyzed Fusion (IFMCF) calculating the muonic atom-nucleus collision cross-section with an improved precision within the optical model for nuclear reactions. The resultant fusion cross section was 2000 barns at 1.4 keV [4] which should be good enough to be used as a fast neutron source [5]. A research program has been initiated to confirm these results theoretically as well as experimentally. For the sake of the theoretical analysis, a few-body computer code has been put forward to handle the nuclear reactions for nucleon transfer. In this paper, an innovative compact reactor concept is proposed, based on IFMCF. In this concept, muons are injected to a gas target of D2 and T2, which is pressurized aerodynamically by the Mach shock wave using a supersonic stream generated in a Laval nozzle [6], [7]. It generates the output power of 28 MW with 1019 cm-3s-1 of fusions by supplying fresh muons of 1016 cm-3s-1 providing 1000 times of catalyzed cycle of reactions. To maintain Q values > 1, assuming 30% efficiency for thermal to electric conversion, the energy supply for muon production can be as low as 8 GeV/muons. One of the possible applications of muon catalyzed fusion is transmutation of long-lived fission products (LLFPs).
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| 6. |
- Kaveeva, E., et al.
(författare)
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Interpretation of the observed radial electric field inversion in the TUMAN-3M tokamak during MHD activity
- 2008
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Ingår i: Nuclear Fusion. - : IOP Publishing. - 0029-5515 .- 1741-4326. ; 48:7
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Tidskriftsartikel (refereegranskat)abstract
- A theoretical model for the toroidal rotation spin-up and generation of a positive radial electric field during the stochastization of plasma edge is put forward. Equations for the toroidal velocity and for modification of the core radial electric field have been derived. A detailed comparison of the model results with the radial electric field and plasma potential measurements during MHD activity in the TUMAN-3M tokamak is presented.
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| 7. |
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| 8. |
- Krlin, L., et al.
(författare)
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Anomalous impurity diffusion in models of tokamak edge plasma turbulence
- 2004
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Ingår i: Czechoslovak Journal of Physics. - 0011-4626 .- 1572-9486. ; 54:1-3, s. 157-163
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Tidskriftsartikel (refereegranskat)abstract
- Using a simple spatially periodical and stationary potential as a model of electrostatic tokamak edge plasma turbulence, we have found recently [1, 2] an anomalous impurity diffusion in this regime. In this contribution, we estimate this diffusion for a more general and realistic form of the potential, which is close to the Hasegawa-Wakatani (HW) potential. As an interesting consequence of the discussed dynamics, we present, possibility of radial electric field generation in the edge turbulence regime. This effect. might play a role in tokamak scenarios with transport barriers.
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| 9. |
- Krlin, L., et al.
(författare)
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Stochastic (E x B) diffusion of ions in a spatially periodical potential field
- 2000
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Ingår i: Physica scripta. T. - 0281-1847. ; T84, s. 221-224
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Tidskriftsartikel (refereegranskat)abstract
- In this contribution, the stochastic (E x B) motion of ions in a homogeneous magnetic field and in a spatially periodical electrostatic potential is discussed. This approach is used for the simulation of ion diffusion in potential structures formed at the boundary plasma in tokamaks. Nonintegrability of the system causes the spatial diffusion of ions. Depending on the choice of parameters, this diffusion has either the usual random-walk character, or appears, for sufficiently strong nonlinearity, in the form of Levy walks. The diffusion coefficient is sufficiently high for heavy impurities. Possible further applications are mentioned.
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| 10. |
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