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  • 1. Askinazi, L. G.
    et al.
    Khrebtov, S.
    Komarov, A. D.
    Komev, V. A.
    Krikunov, S. V.
    Krupnik, L. I.
    Lebedev, S. V.
    Rozhdestvensky, V. V.
    Tendler, Michael B.
    KTH, School of Electrical Engineering (EES), Fusion Plasma Physics.
    Tukachinsky, A. S.
    Vildjunas, M. I.
    Zhubr, N. A.
    GAM evolution in the H-mode discharge in the TUMAN-3M tokamak2011In: 38th EPS Conference on Plasma Physics 2011, EPS 2011 - Europhysics Conference Abstracts, 2011, p. 529-532Conference paper (Refereed)
  • 2. Askinazi, L. G.
    et al.
    Kornev, V. A.
    Krikunov, S. V.
    Krupnik, L. I.
    Lebedev, S. V.
    Smirnov, A. I.
    Tendler, Michael
    KTH, School of Electrical Engineering (EES), Fusion Plasma Physics. KTH, School of Electrical Engineering (EES), Centres, Alfvén Laboratory Centre for Space and Fusion Plasma Physics.
    Tukachinsky, A. S.
    Vildjunas, M. I.
    Zhubr, N. A.
    Plasma potential evolution in various operational modes in the TUMAN-3M tokamak2007In: 34th EPS Conference on Plasma Physics 2007, EPS 2007 - Europhysics Conference Abstracts, 2007, no 3, p. 2010-2013Conference paper (Refereed)
    Abstract [en]

    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.

  • 3. Askinazi, L. G.
    et al.
    Kornev, V. A.
    Krikunov, S. V.
    Krupnik, L. I.
    Lebedev, S. V.
    Smirnov, A. I.
    Tendler, Michael
    KTH, School of Electrical Engineering (EES), Fusion Plasma Physics. KTH, School of Electrical Engineering (EES), Centres, Alfvén Laboratory Centre for Space and Fusion Plasma Physics.
    Tukachinsky, A. S.
    Vildjunas, M. I.
    Zhubr, N. A.
    Radial electric field evolution in various operational modes in the TUMAN-3M tokamak2008In: Journal of Physics, Conference Series, ISSN 1742-6588, E-ISSN 1742-6596, Vol. 123, p. 012010-Article in journal (Refereed)
    Abstract [en]

    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.

  • 4. Askinazi, L. G.
    et al.
    Vildjunas, M. I.
    Zhubr, N. A.
    Komarov, A. D.
    Kornev, V. A.
    Krikunov, S. V.
    Krupnik, L. I.
    Lebedev, S. V.
    Rozhdestvensky, V. V.
    Tendler, Michael
    KTH, School of Electrical Engineering (EES), Fusion Plasma Physics.
    Tukachinsky, A. S.
    Khrebtov, S. M.
    Evolution of geodesic acoustic mode in ohmic H-mode in TUMAN-3M tokamak2012In: Technical physics letters, ISSN 1063-7850, E-ISSN 1090-6533, Vol. 38, no 3, p. 268-271Article in journal (Refereed)
    Abstract [en]

    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.

  • 5. Kaveeva, E.
    et al.
    Rozhansky, V.
    Tendler, Michael
    KTH, School of Electrical Engineering (EES), Fusion Plasma Physics.
    Interpretation of the observed radial electric field inversion in the TUMAN-3M tokamak during MHD activity2008In: Nuclear Fusion, ISSN 0029-5515, E-ISSN 1741-4326, Vol. 48, no 7Article in journal (Refereed)
    Abstract [en]

    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.

  • 6. Kaveeva, E.
    et al.
    Rozhansky, V.
    Tendler, Michael
    KTH, School of Electrical Engineering (EES), Fusion Plasma Physics. KTH, School of Electrical Engineering (EES), Centres, Alfvén Laboratory Centre for Space and Fusion Plasma Physics.
    Mechanism of resonant magnetic perturbation screening2010In: 37th EPS Conference on Plasma Physics 2010, EPS 2010: Volume 2, 2010, p. 823-825Conference paper (Refereed)
  • 7. Krlin, L.
    et al.
    Panek, R.
    Pavlo, P.
    Petrzilka, V.
    Stockel, J.
    Svoboda, V.
    Kuhn, S.
    Tskhakaya, D.
    Tendler, Michael
    KTH, Superseded Departments, Alfvén Laboratory.
    Anomalous impurity diffusion in models of tokamak edge plasma turbulence2004In: Czechoslovak Journal of Physics, ISSN 0011-4626, E-ISSN 1572-9486, Vol. 54, no 1-3, p. 157-163Article in journal (Refereed)
    Abstract [en]

    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.

  • 8. Krlin, L.
    et al.
    Stockel, J.
    Svoboda, V.
    Tendler, Michael
    KTH, Superseded Departments, Alfvén Laboratory.
    Stochastic (E x B) diffusion of ions in a spatially periodical potential field2000In: Physica scripta. T, ISSN 0281-1847, Vol. T84, p. 221-224Article in journal (Refereed)
    Abstract [en]

    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.

  • 9. Kumkova, I
    et al.
    Rutberg, Ph
    Ringheim, Daniel
    KTH, School of Electrical Engineering (EES), Fusion Plasma Physics.
    Tendler, Michael
    KTH, School of Electrical Engineering (EES), Fusion Plasma Physics.
    Plasma Technology Promises Pollution-Free Performance2007In: Modern power systems, ISSN 0260-7840, Vol. 27, no 10, p. 51-53Article in journal (Refereed)
  • 10. Panek, R.
    et al.
    Krlin, L.
    Tendler, Michael
    KTH, School of Electrical Engineering (EES), Fusion Plasma Physics.
    Tskhakaya, D.
    Kuhn, S.
    Svoboda, V.
    Klima, R.
    Pavlo, P.
    Stockel, J.
    Petrzilka, V.
    Anomalous ion diffusion and radial-electric-field generation in a turbulent edge plasma potential weakly correlated in time and space2005In: Physica Scripta, ISSN 0031-8949, E-ISSN 1402-4896, Vol. 72, no 4, p. 327-332Article in journal (Refereed)
    Abstract [en]

    Using a simple model of tokamak-edge-plasma turbulence in the form of a spatially periodic and time-independent electrostatic potential, we have found recently a new type of anomalous impurity diffusion in this regime [1], [2]. In the present contribution, we estimate this diffusion in the test-particle approach for a real turbulent potential obtained in an experiment. A significant difference in the impurity dynannics between the Hamiltonian and drift approaches is observed. As an interesting consequence of these dynamics, the possibility of radial-electric-field generation in the turbulence regimes appears. This effect can be of importance in scenarios related to transport barriers.

  • 11. Panek, R.
    et al.
    Krlin, L.
    Tskhakaya, D.
    Kuhn, S.
    Stockel, J.
    Pavlo, P.
    Tendler, Michael
    KTH, Superseded Departments, Alfvén Laboratory.
    Svoboda, V.
    Petrzilka, V.
    Anomalous diffusion and radial electric field generation due to edge plasma turbulence2004In: Contributions to Plasma Physics, ISSN 0863-1042, E-ISSN 1521-3986, Vol. 44, no 03-jan, p. 203-204Article in journal (Refereed)
  • 12. Pánek, R.
    et al.
    Krlín, L.
    Stöckel, J.
    Tskhakaya Jr., D.
    Kuhn, S.
    Pavlo, P.
    Tendler, Michael
    KTH, School of Electrical Engineering (EES), Fusion Plasma Physics. KTH, School of Electrical Engineering (EES), Centres, Alfvén Laboratory Centre for Space and Fusion Plasma Physics.
    Anomalous impurity diffusion in an experimentally measured turbulent potential2005Conference paper (Refereed)
  • 13. Rozhansky, V.
    et al.
    Kaveeva, E.
    Tendler, Michael
    KTH, School of Electrical Engineering (EES), Fusion Plasma Physics. KTH, School of Electrical Engineering (EES), Centres, Alfvén Laboratory Centre for Space and Fusion Plasma Physics.
    Stochastization and pump-out in edge plasma caused by edge localized modes2015In: Plasma Physics and Controlled Fusion, ISSN 0741-3335, E-ISSN 1361-6587, Vol. 57, no 11, article id 115007Article in journal (Refereed)
    Abstract [en]

    Mechanisms of current generation in edge localized mode (ELM) filaments are discussed. It is shown that dipole type currents should flow in the filaments and that these currents are short-circuited through the ambient plasma of the scrape-off layer. The steady-state monopole currents in the filaments cannot be closed through the ambient plasma and oscillatory currents with Alfven frequency should emerge instead. The dipole type currents in the filaments are sufficient to produce magnetic field perturbations which create a stochastic layer inside the edge transport barrier (ETB) region. The dynamic of penetration of the magnetic field perturbations is analyzed and it is shown that the corresponding time is comparable with the life time of the filaments. At the stage when the ETB region is stochastized by the currents of the filaments the radial electric field becomes less negative or even positive inside the ETB and the onset of outward convective flux takes place. It is shown that this outward flux could lead to the significant pump-out effect - the density decrease in the pedestal region.

  • 14. Rozhansky, V.
    et al.
    Kaveeva, E.
    Tendler, Michael
    KTH, School of Electrical Engineering (EES), Centres, Alfvén Laboratory Centre for Space and Fusion Plasma Physics.
    Stochastization and pump-out in edge plasma caused by ELMs2015In: 42nd European Physical Society Conference on Plasma Physics, EPS 2015, European Physical Society (EPS) , 2015Conference paper (Refereed)
  • 15. Rozhansky, V.
    et al.
    Kaveeva, E.
    Tendler, Michael B.
    KTH, School of Electrical Engineering (EES), Fusion Plasma Physics. KTH, School of Electrical Engineering (EES), Centres, Alfvén Laboratory Centre for Space and Fusion Plasma Physics.
    Interpretation of the observed radial electric field inversion in tuman-3M tokamak during MHD-activity2008In: EPS Conf. Plasma Phys., EPS - Europhys. Conf. Abstr., 2008, no 3, p. 1867-1870Conference paper (Refereed)
  • 16. Rozhansky, V.
    et al.
    Kaveeva, E.
    Veselova, I.
    Voskoboynikov, S.
    Coster, D.
    Tendler, Michael
    KTH, School of Electrical Engineering (EES), Fusion Plasma Physics. KTH, School of Electrical Engineering (EES), Centres, Alfvén Laboratory Centre for Space and Fusion Plasma Physics.
    Impact of the parallel current in the scrape-off layer of a tokamak on the plasma parameters at the divertor plates2011In: 38th EPS Conference on Plasma Physics 2011, EPS 2011: Europhysics Conference Abstracts, 2011, p. 1212-1215Conference paper (Refereed)
  • 17. Rozhansky, V.
    et al.
    Molchanov, P.
    Kaveeva, E.
    Voskoboynikov, S.
    Kirk, A.
    Nardon, E.
    Coster, D.
    Tendler, Michael
    KTH, School of Electrical Engineering (EES), Centres, Alfvén Laboratory Centre for Space and Fusion Plasma Physics. KTH, School of Electrical Engineering (EES), Fusion Plasma Physics.
    Modelling of the edge plasma of MAST in the presence of resonant magnetic perturbations2011In: Nuclear Fusion, ISSN 0029-5515, E-ISSN 1741-4326, Vol. 51, no 8, p. 083009-Article in journal (Refereed)
    Abstract [en]

    The transport code B2SOLPS5.2 is used to simulate L- and H-mode discharges on MAST with and without resonant magnetic perturbations (RMP). The simulated variation of the radial electric field (less negative for RMP) and toroidal rotation (spin-up in the co-current direction for RMP) is in agreement with the experiment. The pump-out effect in the L-modes with high and medium plasma density and in the H-mode is caused by the additional neoclassical radial plasma flow in the electric field modified due to the electron loss along the stochastic field lines. The pump-out in the low-density L-mode can be reproduced only by a significant rise in the turbulent transport coefficients. The modelling suggests strong RMP screening. An analytical model for RMP screening is proposed.

  • 18. Sergeev, V. Y.
    et al.
    Bakhareva, O. A.
    Kuteev, B. V.
    Tendler, Michael
    KTH, School of Electrical Engineering (EES), Fusion Plasma Physics.
    Studies of the impurity pellet ablation in the high-temperature plasma of magnetic confinement devices2006In: Plasma physics reports (Print), ISSN 1063-780X, E-ISSN 1562-6938, Vol. 32, no 5, p. 363-377Article in journal (Refereed)
    Abstract [en]

    The ablation of impurity pellets in tokamak and stellarator plasmas is investigated. Different mechanisms for shielding the heat fluxes from the surrounding plasma to the pellet surface are discussed. A model for impurity pellet ablation is developed that can account for both neutral and electrostatic shielding. It is shown that the experimental values of the impurity pellet ablation rate are well described by the neutral gas shielding model over a wide range of plasma temperatures and densities. Taking into account the electrostatic shielding leads to worse agreement between the predictions of the model and the experimental data; this result still remains unclear. Scaling laws are obtained that allow one to estimate the local ablation rate of impurity pellets made of various materials over a wide range of plasma parameters in the neutral gas shielding model.

  • 19. Severo, J. H. F.
    et al.
    Borges, F. O.
    Alonso, M. P.
    Galvão, R. M. O.
    Theodoro, V. C.
    Berni, L. A.
    Jeronimo, L. C.
    Elizondo, J. I.
    Figueiredo, A. C. A.
    Machida, M.
    Nascimento, I. C.
    Kuznetsov, Yu.K.
    Sanada, E. K.
    Usuriaga, O. C.
    Tendler, Michael
    KTH, School of Electrical Engineering (EES), Fusion Plasma Physics.
    Error analysis in the electron temperature measurements in TCABR2012In: Journal of Physics, Conference Series, ISSN 1742-6588, E-ISSN 1742-6596, Vol. 370, no 1, p. 012045-Article in journal (Refereed)
    Abstract [en]

    An analytical method is proposed to evaluate the experimental uncertainty in the electron temperature measurements in the TCABR tokamak. Solving the integral equation resulting from the convolution of two functions, one representing, the scattered light and the other the spectral apparatus function, i.e., the polychromator, an analytical expression for the electron temperature is obtained, from which the uncertainty in the measured value is readily evaluated. The results show that the major contribution to the error comes from the noise in the signal; the uncertainties in the filters parameters do not contribute significantly to the total error.

  • 20. Severo, J. H. F.
    et al.
    Nascimento, I. C.
    Kuznetov, Yu K.
    Tsypin, V. S.
    Galvao, R. M. O.
    Tendler, Michael
    KTH, School of Electrical Engineering (EES), Fusion Plasma Physics.
    Plasma rotation measurement in small tokamaks using an optical spectrometer and a single photomultiplier as detector2007In: Review of Scientific Instruments, ISSN 0034-6748, E-ISSN 1089-7623, Vol. 78, no 4Article in journal (Refereed)
    Abstract [en]

    The method for plasma rotation measurement in the tokamak TCABR is reported in this article. During a discharge, an optical spectrometer is used to scan sequentially spectral lines of plasma impurities and spectral lines of a calibration lamp. Knowing the scanning velocity of the diffraction grating of the spectrometer with adequate precision, the Doppler shifts of impurity lines are determined. The photomultiplier output voltage signals are recorded with adequate sampling rate. With this method the residual poloidal and toroidal plasma rotation velocities were determined, assuming that they are the same as those of the impurity ions. The results show reasonable agreement with the neoclassical theory and with results from similar tokamaks.

  • 21. Severo, J. H. F.
    et al.
    Nascimento, I. C.
    Kuznetsov, Y. K.
    Galvao, R. M. O.
    Guimaraes, Z. O.
    Borges, F. O.
    Usuriaga, O. C.
    Elizondo, J. I.
    de Sa, W. P.
    Sanada, E. K.
    Tendler, Michael
    KTH, School of Electrical Engineering (EES), Centres, Alfvén Laboratory Centre for Space and Fusion Plasma Physics.
    Kuznetsov, Yu K.
    Guimaraes-Filho, Z. O.
    Temporal behaviour of toroidal rotation velocity in the TCABR tokamak2009In: Nuclear Fusion, ISSN 0029-5515, E-ISSN 1741-4326, Vol. 49, no 11Article in journal (Refereed)
    Abstract [en]

    A new method for determining the temporal evolution of plasma rotation is reported in this work. The method is based upon the detection of two different portions of the spectral profile of a plasma impurity line, using a monochromator with two photomultipliers installed at the exit slits. The plasma rotation velocity is determined by the ratio of the two detected signals. The measured toroidal rotation velocities of C III (4647.4 angstrom) and C VI (5290.6 angstrom), at different radial positions in TCABR discharges, show good agreement, within experimental uncertainty, with previous results (Severo et al 2003 Nucl. Fusion 43 1047). In particular, they confirm that the plasma core rotates in the direction opposite to the plasma current, while near the plasma edge (r/a > 0.9) the rotation is in the same direction. This technique was also used to investigate the dependence of toroidal rotation on the poloidal position of gas puffing. The results show that there is no dependence for the plasma core, while for plasma edge (r/a > 0.9) some dependence is observed.

  • 22. Severo, J. H. F.
    et al.
    Nascimento, I. C.
    Tsypin, V. S.
    Kuznetsov, Y. K.
    Saettone, E. A.
    Vannucci, A.
    Galvao, R. M. O.
    Tendler, Michael
    KTH, Superseded Departments, Alfvén Laboratory.
    Mikhailovskii, A. B.
    Magnetic islands and plasma rotation in the Tokamak Chauffage Alfven Bresilien tokamak2004In: Physics of Plasmas, ISSN 1070-664X, E-ISSN 1089-7674, Vol. 11, no 2, p. 846-848Article in journal (Refereed)
    Abstract [en]

    Collisional plasma rotation in the Tokamak Chauffage Alfven Bresilien (TCABR) tokamak [J. H. F. Severo, I. C. Nascimento, V. S. Tsypin, and R. M. O. Galvao, Nucl. Fusion 43, 1047 (2003)] has been experimentally studied. It was found that the measured plasma poloidal rotation velocity agrees within error limits with neoclassical theoretical predictions, and toroidal velocity with experimental results obtained in analogous tokamaks, almost everywhere along the minor radius r, except for measurements at r/asimilar or equal to0.56 and r/asimilar or equal to0.89 (the minor radius of TCABR tokamak a=18 cm). For the first point, the measured plasma rotation velocities are higher than the velocity of the background plasma, respectively similar to30% and similar to10% for the poloidal and toroidal rotation velocities. Using a set of 22 Mirnov coils displaced poloidally, magnetic field perturbations were measured in shots adjusted to reproduce the ones of the previous plasma rotation measurements, and the results confirm that in the region r/asimilar or equal to0.89 the plasma rotates together with the magnetic island (3,1).

  • 23. Severo, J. H. F.
    et al.
    Ronchi, G.
    Galvao, R. M. O.
    Nascimento, I. C.
    Guimaraes-Filho, Z. O.
    Kuznetsov, Yu. K.
    Nave, M. F. F.
    Oliveira, A. M.
    do Nascimento, F.
    Tendler, Mikael
    KTH, School of Electrical Engineering (EES), Fusion Plasma Physics.
    Investigation of rotation at the plasma edge in TCABR2015In: Nuclear Fusion, ISSN 0029-5515, E-ISSN 1741-4326, Vol. 55, no 9, article id 093001Article in journal (Refereed)
    Abstract [en]

    This paper summarizes experimental results from recent studies on intrinsic rotation at the plasma edge of the TCABR tokamak. These results were obtained after upgrading the number of channels of the rotation diagnostic to three. The measurements were carried out in the collisional (Pfirsch-Schluter) regime and the rotation profiles of the ions were obtained from the Doppler shifts of the impurity carbon lines, CIII (464.74 nm), and CVI (529.06 nm). Results on the correlation between toroidal rotation at the plasma edge and direction of gas injection are also presented. They indicate that the direction of gas injection has a small effect on rotation; the velocity of the background neutral hydrogen is affected by direct momentum transfer from the injected gas (also hydrogen), while the carbon ions' velocity is affected by inward radial friction force between the injected gas atoms and ions, increasing their velocity in the opposite sense of the plasma current.

  • 24. Severo, J. H. F.
    et al.
    Tsypin, V. S.
    Nascimento, I. C.
    Galvao, R. M. O.
    Tendler, Michael
    KTH, Superseded Departments, Alfvén Laboratory.
    Fagundes, A. N.
    Neoclassical ion transport in the edge of axially-symmetric arbitrary cross-section tokamak with plasma subsonic toroidal flows2002In: Brazilian journal of physics, ISSN 0103-9733, E-ISSN 1678-4448, Vol. 32, no 1, p. 13-19Article in journal (Refereed)
    Abstract [en]

    General metrics of large aspect ratio tokamaks is used in the paper. General expressions for the neoclassical poloidal plasma rotation V-2(theta) and radial ion heat flux Gamma(Ti) are obtained. Their dependence 2 on the squared Mach number alpha = U-zetai(2)/c(5)(2) is analyzed (here U-zetai is the ion toroidal velocity and c(s) is the sound velocity, respectively). Some interesting peculiarities of this dependence are emphasized.

  • 25. Severo, J.H.F.
    et al.
    Borges, F.O.
    Alonso, M.P.
    Galvao, R.M.P.
    Theodoro, V.C.
    Berni, A.L.
    Joronimo, L.C.
    Elizondo, J.I.
    Figuerdo, A.C.A.
    Machida, M.
    Nascimento, A.C.
    Kuznetsov, Y.K.
    Sanada, E.K.
    Usuriaga, O.C.
    Tendler, Michael
    KTH, School of Electrical Engineering (EES), Fusion Plasma Physics.
    Error analysis in the electron temperature measurement in TCA BR tokamak2011In: Journal of Physics, Conference Series, ISSN 1742-6588, E-ISSN 1742-6596Article in journal (Refereed)
  • 26.
    Tendler, Michael
    KTH, School of Electrical Engineering (EES), Fusion Plasma Physics. KTH, School of Electrical Engineering (EES), Centres, Alfvén Laboratory Centre for Space and Fusion Plasma Physics.
    Issues of Electric Fields in Fusion Devices2010In: Plasma and Fusion Research, ISSN 1880-6821, E-ISSN 1880-6821, Vol. 5, no S21004Article in journal (Refereed)
    Abstract [en]

    At present it is well understood that the key element in the transition physics is the origin of the strong radialelectric field and suppression of the turbulence fluctuation level by a strong poloidal rotation in the E × B fields.As a result, the transport coefficients are strongly reduced at fixed places and transport barriers with steep densityand temperature gradients are formed near the separatrix or the last closed flux surface (ETB) or in the core region(ITB). The key element in the transition physics is the origin of the strong radial electric field. The impact of themomentum transport is brought to light.

  • 27.
    Tendler, Michael
    KTH, School of Electrical Engineering (EES), Fusion Plasma Physics.
    Major achievements and challenges of fusion research2015In: Physica Scripta, ISSN 0031-8949, E-ISSN 1402-4896, Vol. 90, no 9, article id 098002Article in journal (Other academic)
    Abstract [en]

    The ITER project is truly at the frontier of knowledge, a collective effort to explore the tantalizing future of free, clean and inexhaustible energy offered by nuclear fusion. Where the Large Hadron Collider at CERN pushes the boundaries of physics to find the origins of matter, the ITER Project seeks to give humans an endless stream of power which could have potentially game-changing consequences for the entire planet. Seminal contributions to the general physics knowledge accomplished by the plasma physics research for the benefit of the ITER project will be brought to light. The legacy of Professor H Alfven within the framework of the ITER project will be described.

  • 28.
    Tendler, Michael
    KTH, Superseded Departments, Alfvén Laboratory.
    Plasma flows within the context of biasing experiments2004In: Plasma Science & Technology, ISSN 1009-0630, Vol. 6, no 1, p. 2123-2129Article in journal (Refereed)
    Abstract [en]

    The understanding and reduction of turbulent transport in magnetic confinement devices is not only an academic task, but also the matter of practical interest, since high confinement is chosen as the regime for ITER and possible future reactors it reduces both the size and the cost. Since the pioneering work on CCT a lot of work has been devoted to the effect of electric field biasing carried out on many tokamaks, which in general leads to a strongly varying radial electric fields as a function of radius and a resulting sheared E--> x B--> flow, giving rise to improved confinement properties. The issue of plasma flows is utterly fundamental for understanding of tokamaks aimed at the achievement of fusion energy. This appears in the well known neoclassical theory as the most accomplished and self-consistent basis for understanding of fusion plasmas. It pertains to the novel concept of zonal flows emerging from the recent development of gyro-kinetic transport codes. The poloidal and toroidal flows are also crucial for the concept of the electric field shear suppression of plasma turbulence in tokamaks. Yet, this timely and topical issue has remained largely unaddressed experimentally because of great difficulties of measuring flows in plasmas. Recently, the team of scientists from all over the world developed innovative configuration of probes yielding the flow velocity locally. This timely and topical diagnostics has been successfully applied on many tokamaks ranging from the huge JET through medium TEXTOR to a small CASTOR due to the excellent collaboration and coordination between research teams. Results caused large interest of fusion community born out by numerous invited talks delivered at the major international meetings.

  • 29.
    Tendler, Michael
    KTH, Superseded Departments, Alfvén Laboratory.
    Selforganisation in plasma physics: Special Issue Dedicated to Professor Lennart Stenflo on the Occasion of His 65th Birthday2004In: Physica Scripta, ISSN 0031-8949, E-ISSN 1402-4896, ISSN 0281-1847, Vol. T113, p. 51-55Article in journal (Refereed)
    Abstract [en]

    The bottom line of modern plasma physics addressing a many body problem is the lack of thermodynamic potentials for the system in which fluxes are no longer linear functions of forces or gradients. Indeed far from the classical equilibrium, a system can still converge to a stationary state, yet not defined by the proper thermodynamic potential in contrast to the entropy production principle valid only for a linear or weakly nonlinear system. In this case, we confront an important issue of stability of a strongly nonequilibrium system occurring and lacking the thermodynamic potential. In a linear system the equilibrium is defined by the minimum of the potential and therefore the stability of the resulting steady - state is easily found. Of course, any fluctuation causes a deviation from the equilibrium. Yet, linear or weakly nonlinear system will return to this steady state due to the second law of thermodynamics. Hence, the existence of the thermodynamic potential makes the equilibrium very robust. Given the potential, any evolution of a weakly nonlinear system will result in a static stationary state. In contrast, a strongly nonlinear system may loose a steady state very easily due to instability perturbed by fluctuations. If this is the case the fluctuation will be amplified until a very different steady state not described by a minimum of the thermodynamic potential emerges. In more detail, instability in a strongly nonlinear situation has always to exceed a given threshold in order to yield a different equilibrium far from an original static steady state. In fluids and plasmas it is well-known that any laminar motion can transform into a turbulent motion once a given fluid velocity is exceeded. It may appear that this transition yields a chaotic strongly fluctuating equilibrium. Indeed although at the macroscopic level this novel equilibrium may appear to be a complete disorder and chaos, it is found experimentally that at the microscopic level the new equilibrium is characterised by a highly ordered vortices [1] resulting due to the inherent selforganization of this system. Here, it is important to keep in mind that fluid equations describing this phenomenon are highly nonlinear. Multiple scales emerge both in space and in time, thereby pointing to the scale free nature of the fractal geometry. The convection emerging due to multiscale vortices is organised to enhance the thermal conductivity in contrast to the second law of thermodynamics. The reason for this is that a fluctuation bound to dissipate within the framework of the weakly nonlinear approach is significantly amplified and ultimately governs the system. The entropy is of course provided by an external source in the environment and there is no contradiction to the second law. Hence, a novel highly organised equilibrium emerges which may also be time dependent. To this end, turbulent vortices differ very much from equilibrium structures like crystals because here thermal fluxes provide the order in contrast to the dissipation only in linear systems. Novel dissipative structures arise from a chaotic particle motion on all possible time and space scales.

  • 30.
    Tendler, Michael
    et al.
    KTH, School of Electrical Engineering (EES), Fusion Plasma Physics.
    Rutberg, P.
    van Oost, G.
    Plasma based waste treatment and energy production2005In: Plasma Physics and Controlled Fusion, ISSN 0741-3335, E-ISSN 1361-6587, Vol. 47, no 5 A, p. A219-A230Article in journal (Refereed)
    Abstract [en]

    During the past centuries, industrial processes and energy conversion plants have shown no or little care for environmental quality. The result is a huge accumulation of pollution and hazardous by-products, left as a heritage for the present and future generations. Recuperation of by-products or thermal energy is not only motivated by cost saving, but also by resource saving considerations. Environmental awareness is more than staying within the lines of the existing regulations. By the application of a plasma based system to a wide range of possible feedstocks which are CO2 neutral, a clean syngas of high caloric value is produced from the organic substances simultaneously with a non-leachable vitrified lava from the inorganic substances. The results will provide the advanced technology for the environmentally friendly treatment of hazardous wastes, biomass and low grade fuel. The driving force behind the task is to give priority to environmental quality at affordable costs. Thus, the investigation of ways to increase the efficiency of the process is very important. A plasma based remediation system is the only technology that prevents undesired pollution in the by-products and end product (such as syngas or other gases). The problem to be solved is twofold: recuperate clean energy from waste and renewables without pollution at affordable costs. Such a technique fulfils the objectives of sustainable development. Today, one of the main reasons that restricts the use of plasma based methods is the cost of electrical energy. The crucial element is the plasma torch performance. Hence, the physics of modem plasma torches is addressed in detail. The optimistic scenario holds the promise to provide 10-15% of the energy needs for the European Union (EU). Thus, the investigation of ways to increase the efficiency of the process is very important.

  • 31.
    Tendler, Michael
    et al.
    KTH, Superseded Departments, Alfvén Laboratory.
    Van Oost, G.
    Stockel, J.
    Models for transitions into regimes with enhanced confinement2002In: Comments on modern physics, ISSN 1560-5892, Vol. 2, no 6, p. C203-C214Article in journal (Refereed)
    Abstract [en]

    The model based upon the concept of E x B flow velocity shear suppression is explained. It is asserted that there are models enabling to understand the physics involved in L-H transitions. The issue is more whether one wishes to employ the theoretical results available in order to interpret the reality.

  • 32.
    Tendler, Michael
    et al.
    KTH, Superseded Departments, Alfvén Laboratory.
    VanOost, G.
    Krlin, L.
    Panek, R.
    Stockel, J.
    Physics of transport barriers2004In: Brazilian journal of physics, ISSN 0103-9733, E-ISSN 1678-4448, Vol. 34, no 4B, p. 1822-1827Article in journal (Refereed)
    Abstract [en]

    The concept of ExB flow velocity shear suppression is utterly fundamental in modem fusion research. It is asserted that there are models enabling to understand the physics involved in LH transitions. To improve the understanding of the mechanisms leading to the formation of Transport Barriers, especially the relation between Internal and Edge barriers it is necessary to invoke the issue of electric fields. Edge transport barriers are the feature of the H-mode, the baseline regime of ITER, whereas Internal Transport Barriers are used to develop regimes that might be employed for steady state operation of ITER, definitely beneficial for design and operation of fusion power plants in the future. Their synergy will be addressed. Plasma flows are closely connected to electric fields. Therefore, their role is crucial for understanding of tokamaks aimed at the achievement of fusion energy. This appears in the well known neoclassical theory as the most accomplished and selfconsistent basis for understanding of fusion plasmas. It pertains to the novel concept of zonal flows emerging from the recent development of gyro-kinetic transport codes. The equilibrium poloidal and toroidal flows are also crucial for the concept of the electric field shear suppression of plasma turbulence in tokamaks. Yet, this timely and topical issue has remained largely unaddressed experimentally because of great difficulties in measuring flows in plasmas.

  • 33. Tsypin, V. S.
    et al.
    Galvao, R. M. O.
    Nascimento, I. C.
    Tendler, Michael
    KTH, Superseded Departments, Alfvén Laboratory.
    Severo, J. H. F.
    Ruchko, L. F.
    Role of trapped and circulating particles in inducing current drive and radial electric field by Alfven waves in tokamaks2002In: Journal of Plasma Physics, ISSN 0022-3778, E-ISSN 1469-7807, Vol. 67, p. 301-308Article in journal (Refereed)
    Abstract [en]

    Absorption by trapped particles is supposed to seriously hinder current drive by Alfven waves. However, it is shown in this paper that the same effect is rather beneficial for the emergence of the radial electric field induced by these waves, which is important for creating and maintaining transport barriers in tokamaks.

  • 34. Tsypin, V. S.
    et al.
    Vladimirov, S. V.
    Galvao, R. M. O.
    Nascimento, I. C.
    Tendler, Michael
    KTH, Superseded Departments, Alfvén Laboratory.
    Kuznetsov, Y. K.
    Particle flows in dusty plasmas of the tokamak edge2004In: Physics of Plasmas, ISSN 1070-664X, E-ISSN 1089-7674, Vol. 11, no 8, p. 4138-4141Article in journal (Refereed)
    Abstract [en]

    In this Brief Communication the plasma flows and ambipolar electric field induced due to the temperature stresses on ions are estimated. These flows are similar to the plasma residual rotations in tokamaks, but are related to dust contamination of tokamak plasmas. The induced electric field might be very important for creating transport barriers in tokamaks.

  • 35. Van Oost, G.
    et al.
    Adamek, J.
    Antoni, V.
    Balan, P.
    Boedo, J. A.
    Devynck, P.
    Duran, I.
    Eliseev, L.
    Gunn, J. P.
    Hron, M.
    Ionita, C.
    Jachmich, S.
    Kirnev, G. S.
    Martines, E.
    Melnikov, A.
    Schrittwieser, R.
    Silva, C.
    Stockel, J.
    Tendler, Michael
    KTH, Superseded Departments, Alfvén Laboratory.
    Varandas, C.
    Van Schoor, M.
    Vershkov, V.
    Weynants, R. R.
    Turbulent transport reduction by E x B velocity shear during edge plasma biasing: recent experimental results2003In: Plasma Physics and Controlled Fusion, ISSN 0741-3335, E-ISSN 1361-6587, Vol. 45, no 5, p. 621-643Article in journal (Refereed)
    Abstract [en]

    Experiments in the tokamaks TEXTOR, CASTOR, T-10 and ISTTOK, as well as in the reversed field pinch RFX have provided new and complementary evidence on the physics of the universal mechanism of E x B velocity shear stabilization of turbulence, concomitant transport barrier formation and radial conductivity by using various edge biasing techniques. In TEXTOR the causality between transport reduction and induced electric fields in the edge has been for the first time clearly demonstrated. The high electric field gradients have been identified as the cause for the quenching of turbulent cells. A quantitative analysis of the measured transport reduction is in good agreement with theoretical predictions. The scaling of plasma turbulence suppression with velocity shear has been established, revealing the density-potential cross-phase as a key element. Reduction in poloidal electric field, temperature, and density fluctuations across the shear layer lead to a reduction of the anomalous conducted and convected heat fluxes resulting in an energy transport barrier that is measured directly. In CASTOR the biasing electrode is placed at the separatrix in a non-intrusive configuration which has demonstrated strongly sheared electric fields and consequent improvement of the global particle confinement, as predicted by theory. The impact of sheared E x B flow on edge turbulent structures has been measured directly using a comprehensive set of electrostatic probe arrays as well as emissive probes. Measurements with a full poloidal Langmuir probe array have revealed quasi-coherent electrostatic waves in the SOL with a dominant mode number equal to the edge safety factor. In T-10 edge biasing is clearly improving the global performance of ECR heated discharges. Reflectometry and heavy ion beam probe measurements show the existence of a narrow plasma layer with strong suppression of turbulence. On ISTTOK, the influence of alternating positive and negative electrode and (non-intrusive) limiter biasing has been compared. Electrode biasing is found to be more efficient in modifying the radial electric field E, and confinement, limiter biasing acting mainly on the SOL. In the RFX reversed field pinch it has been demonstrated that also in RFPs biasing can increase the local E x B velocity shear in the edge region, and hence substantially reduce the local turbulence driven particle flux mainly due to a change in the relative phase between potential and density fluctuations.

  • 36. Van Oost, G.
    et al.
    Bulanin, V.
    Donne, A. J. H.
    Gusakov, E.
    Kramer-Flecken, A.
    Krupnik, L.
    Heikkinen, J.
    Melnikov, A.
    Razumova, K.
    Rozhansky, V.
    Stockel, J.
    Tendler, Michael
    KTH, School of Electrical Engineering (EES), Fusion Plasma Physics.
    Van Schoor, M.
    Vershkov, V.
    Zajac, J.
    Altukov, A.
    Andreev, V.
    Askinazi, L.
    Bondarenko, I.
    Dnestrovskij, A.
    Eliseev, L.
    Esipov, L.
    Grashin, S.
    Gurchenko, A.
    Hogeweij, G. M. D.
    Kantor, M.
    Kaveeva, E.
    Kiviniemi, T.
    Khrebtov, S.
    Kouprienko, D.
    Kurki-Suonio, T.
    Lashkul, S.
    Lebedev, S.
    Leerink, S.
    Lysenko, S.
    Ogando, F.
    Perfilov, S.
    Petrov, A.
    Popov, A.
    Shelukhin, D.
    Shurygin, F.
    Soldatov, S.
    Stepanov, A.
    Xu, Y.
    Kraemer-Flecken, A.
    Stoeckel, J.
    ROLE OF TURBULENCE AND ELECTRIC FIELDS IN THE FORMATION OF TRANSPORT BARRIERS AND THE ESTABLISHMENT OF IMPROVED CONFINEMENT IN TOKAMAK PLASMAS THROUGH INTER-MACHINE COMPARISON2009Article in journal (Refereed)
    Abstract [en]

    Over the past decade new regimes of tokamak operation have been identified, whereby electrostatic and magnetic turbulence responsible for anomalous transport, can be externally suppressed, leading to improved confinement. Although turbulence measurements have been performed on many confinement devices, the insight gained from these experiments is relatively limited. To make further progress in the understanding of plasma turbulence in relation to improved confinement and transport barriers, an extensive experimental and theoretical research programme should be undertaken. The present INTAS project investigates the correlations between on the one hand the occurrence of transport barriers and improved confinement in the tokamaks TEXTOR & T-10 and Tore Supra as well as on the smaller-scale tokamaks FT-2, TUMAN-3M and CASTOR, and on the other hand electric fields, modified magnetic shear and electrostatic and magnetic turbulence using advanced diagnostics with high spatial and temporal resolution. This is done in a strongly coordinated way and exploiting the complementarity of TEXTOR and T-10 and the backup potential of the other tokamaks, which together have all the relevant experimental tools and theoretical expertise. Advanced theoretical models and numerical simulations are used to check the experimental results.

  • 37. Van Oost, G.
    et al.
    Gunn, J. P.
    Melnikov, A.
    Stockel, J.
    Tendler, Michael
    KTH, Superseded Departments, Alfvén Laboratory.
    The role of radial electric fields in the tokamaks TEXTOR-94, CASTOR, and T-102001In: Czechoslovak Journal of Physics, ISSN 0011-4626, E-ISSN 1572-9486, Vol. 51, no 10, p. 957-975Article in journal (Refereed)
    Abstract [en]

    Radial electric fields (E-r) and their role in the establishment of edge transport barriers and improved confinement have been studied in the tokamaks TEXTOR-94 and CASTOR, where E-r is externally applied to the plasma in a controlled way using a biased electrode, as well as in the tokamak T-10 where an edge transport barrier (H-mode) is obtained during electron-cyclotron resonance heating (ECRH) of the plasma. The physics of radial currents was studied and the radial conductivity in the edge of TEXTOR-94 (R = 1.75 m, a = 0.46 m) was found to be dominated by recycling (ion-neutral collisions) at the last closed flux surface (LCFS) and by parallel viscosity inside the LCFS. From a performance point of view (edge engineering), such electrode biasing was shown to induce a particle transport barrier, a reduction of particle transport, and a concomitant increase in energy confinement. An H-mode-like behaviour can be induced both with positive and negative electric fields. Positive as well as negative electric fields were shown to strongly affect the exhaust of hydrogen, helium, and impurities, not only in the H-mode-like regime. The impact of sheared radial electric fields on turbulent structures and flows at the plasma edge is investigated on the CASTOR tokamak (R = 0.4 m, a = 0.085 m). A non-intrusive biasing scheme that we call separatrix biasing is applied whereby the electrode is located in the scrape-off layer (SOL) with its tip just touching the LCFS. There is evidence of strongly sheared radial electric field and E x B flow, resulting in the formation of a transport barrier at the separatrix. Advanced probe diagnosis of the edge region has shown that the E x B shear rate that arises during separatrix biasing is larger than for standard edge plasma biasing. The plasma flows, especially the poloidal E x B drift velocity, are strongly modified in the sheared region, reaching Mach numbers as high as half the sound speed. The corresponding shear rates (approximate to5 x 10(6) s(-1)) derived from both the flow and electric field profiles are in excellent agreement and are at least an order of magnitude higher than the growth rate of unstable turbulent modes as estimated from fluctuation measurements. During ECRH in the tokamak T-10 (R = 1.5 m, a = 0.3 m), a regime of improved confinement is obtained with features resembling those in the H-mode in other tokamaks. Using a heavy ion beam probe, a narrow potential well is observed near the limiter together with the typical features of the L-H transition. The time evolution of the plasma profiles during L-H and H-L transitions is clearly correlated with that of the density profile and the formation of a transport barrier near the limiter, The edge electric field is initially positive after the onset of ECRH. It changes its sign during the L-H transition and grows till a steady condition is reached. Similar to the biasing experiments in TEXTOR-94 and CASTOR, the experimentally observed transport barrier is a barrier for particles.

  • 38. Van Oost, G.
    et al.
    Tendler, Michael
    KTH, Superseded Departments, Alfvén Laboratory.
    Stockel, J.
    Role of electric field in plasma confinement and exhaust2000In: Czechoslovak Journal of Physics, ISSN 0011-4626, E-ISSN 1572-9486, Vol. 50, p. 11-24Article in journal (Refereed)
    Abstract [en]

    Experimental and theoretical aspects of the role of electric fields in plasma confinement and exhaust are overviewed. The history of the discovery of the importance of electric fields in plasmas is depicted. The correlation between radial electric fields and plasma rotation is outlined. The concept of E x B flow velocity shear suppression is explained and modelled. Edge polarization results on the CASTOR tokamak are presented. Recent results in the formation of internal transport barriers are summarized.

  • 39. Verdoolaege, G.
    et al.
    Karagounis, G.
    Tendler, Michael
    KTH, School of Electrical Engineering (EES), Fusion Plasma Physics. KTH, School of Electrical Engineering (EES), Centres, Alfvén Laboratory Centre for Space and Fusion Plasma Physics.
    Oost, G. V.
    Pattern recognition in probability spaces for visualization and identification of plasma confinement regimes and confinement time scaling2012In: Plasma Physics and Controlled Fusion, ISSN 0741-3335, E-ISSN 1361-6587, Vol. 54, no 12, p. 124006-Article in journal (Refereed)
    Abstract [en]

    Pattern recognition is becoming an increasingly important tool for making inferences from the massive amounts of data produced in fusion experiments. The purpose is to contribute to physics studies and plasma control. In this work, we address the visualization of plasma confinement data, the (real-time) identification of confinement regimes and the establishment of a scaling law for the energy confinement time. We take an intrinsically probabilistic approach, modeling data from the International Global H-mode Confinement Database with Gaussian distributions. We show that pattern recognition operations working in the associated probability space are considerably more powerful than their counterparts in a Euclidean data space. This opens up new possibilities for analyzing confinement data and for fusion data processing in general. We hence advocate the essential role played by measurement uncertainty for data interpretation in fusion experiments.

  • 40. Vicente, Jose
    et al.
    LASHKUL, Serguei I.
    Tendler, Michael
    KTH, School of Electrical Engineering (EES), Fusion Plasma Physics. KTH, School of Electrical Engineering (EES), Centres, Alfvén Laboratory Centre for Space and Fusion Plasma Physics.
    SHATALIN, Serguei V.
    VEKSHINA, Elena
    SIDOROV, Anton V.
    ESIPOV, Lev A.
    Blobs on the High Field Side of Tokamaks2010In: Plasma and Fusion Research, ISSN 1880-6821, E-ISSN 1880-6821, Vol. 5, no S2013Article in journal (Refereed)
    Abstract [en]

    Turbulence-induced high density filaments, blobs, might represent the new paradigm for radial convectivetransport in the Scrape-Off-Layer of magnetic fusion devices. Models for individual blob dynamics, consideringtheir generation on the Low Field Side (LFS) of the torus have been put forward. We investigate the existence ofblobs in the peripheral region of the High Field Side (HFS) of the FT-2 tokamak. Langmuir probe measurementsare used to detect and characterize blobs. The results were obtained in plasmas with enhanced Lower HybridHeating and data was acquired with a new fast data acquisition system with 50MHz sampling rate. While themajority of the blobs are observed to move towards the wall as expected, some are observed to move inwardstowards the core. This effect is not understood in the light of existing models for the LFS where only the outwarddirection is expected. Further characterization of plasma blobs should therefore involve both HFS and LFS. Thiscould be done at ASDEX Upgrade where reflectometry systems are capable of measuring simultaneously thedensity turbulence on both HFS and LFS. The dependence between radial velocity, size and density of the blobsis also investigated.

  • 41. Zhao, M. L.
    et al.
    Chen, Y. P.
    Guo, H. Y.
    Ye, M. Y.
    Tendler, Michael
    KTH, School of Electrical Engineering (EES), Fusion Plasma Physics.
    Li, G. Q.
    Luo, Z. P.
    Modeling of divertor geometry effects in China fusion engineering testing reactor by SOLPS/B2-Eirene2014In: Physics of Plasmas, ISSN 1070-664X, E-ISSN 1089-7674, Vol. 21, no 5, p. 052503-Article in journal (Refereed)
    Abstract [en]

    The China Fusion Engineering Testing Reactor (CFETR) is currently under design. The SOLPS/B2-Eirene code package is utilized for the design and optimization of the divertor geometry for CFETR. Detailed modeling is carried out for an ITER-like divertor configuration and one with relatively open inner divertor structure, to assess, in particular, peak power loading on the divertor target, which is a key issue for the operation of a next-step fusion machine, such as ITER and CFETR. As expected, the divertor peak heat flux greatly exceeds the maximum steady-state heat load of 10MW/m(2), which is a limit dictated by engineering, for both divertor configurations with a wide range of edge plasma conditions. Ar puffing is effective at reducing divertor peak heat fluxes below 10MW/m(2) even at relatively low densities for both cases, favoring the divertor configuration with more open inner divertor structure.

1 - 41 of 41
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