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184 results on '"Escande, D. F."'

1. Modelling of impurity heating during reconnections in a Reverse Field Pinch device as due to parallel electric field acceleration and chaos-induced thermalization

Author

Sattin, F., Escande, D. F., Gobbin, M., and Predebon, I.

Subjects
Physics - Plasma Physics
Abstract

The ion temperature during magnetic reconnections measured along the direction of the magnetic field at the MST Reverse Field Pinch has not yet received a satisfactory theoretical explanation. In this work we argue that it is consistent with a picture of ion energization by the parallel electric fields generated by the plasma during reconnection, and thermalization due to the chaotic ion dynamics. Three possible sources of randomness are pointed out: particle motion along static stochastic magnetic field lines, breakup of the adiabatic ion dynamics caused by the strong gradient nonlinearity of the magnetic field, parallel acceleration along stochastic time-dependent electric fields. The three mechanisms are likely operative simultaneously; regardless the specific mechanism active, the correct scaling laws with ion parameters are recovered. Furthermore, we argue that quantitative agreement can be obtained by feeding the model with realistic values for the plasma conditions.

Published
2023

2. Thresholdless stochastic particle heating by a single wave

Author

Sattin, F. and Escande, D. F.

Subjects
Physics - Plasma Physics
Abstract

Stochastic heating is a well-known mechanism through which magnetized particles may be energized by low-frequency electromagnetic waves. In its simplest version, under spatially homogeneous conditions, it is known to be operative only above a threshold in the normalized wave amplitude, which may be a demanding requisite in actual scenarios, severely restricting its range of applicability. In this work we show, by numerical simulations supported by inspection of the particle Hamiltonian, that allowing for even a very weak spatial inhomogeneity completely removes the threshold, trading the requirement upon the wave amplitude with a requisite upon the duration of the interaction between wave and particle. The thresholdless chaotic mechanism considered here is likely to be applicable to other inhomogeneous systems., Comment: V2. Some minor mistakes corrected

Published
2022
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3. A unified model of density limit in fusion plasmas

Author

Zanca, P., Sattin, F., Escande, D. F., Pucella, G., and Tudisco, O.

Subjects
Physics - Plasma Physics
Abstract

A limit for the edge density, ruled by radiation losses from light impurities, is established by a minimal cylindrical magneto-thermal equilibrium model. For ohmic tokamak and reversed field pinch the limit scales linearly with the plasma current, as the empirical Greenwald limit. The auxiliary heating adds a further dependence, scaling with the 0.4 power, in agreement with L-mode tokamak experiments. For a purely externally heated configuration the limit takes on a Sudo-like form, depending mainly on the input power, and is compatible with recent Stellarator scalings.

Published
2016
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4. Effect of magnetic perturbations on the 3D MHD self-organization of shaped tokamak plasmas

Author

Bonfiglio, D., Cappello, S., Veranda, M., Chacón, L., and Escande, D. F.

Subjects
Physics - Plasma Physics
Abstract

The effect of magnetic perturbations (MPs) on the helical self-organization of shaped tokamak plasmas is discussed in the framework of the nonlinear 3D MHD model. Numerical simulations performed in toroidal geometry with the \textsc{pixie3d} code [L. Chac\'on, Phys. Plasmas {\bf 15}, 056103 (2008)] show that $n=1$ MPs significantly affect the spontaneous quasi-periodic sawtoothing activity of such plasmas. In particular, the mitigation of sawtooth oscillations is induced by $m/n=1/1$ and $2/1$ MPs. These numerical findings provide a confirmation of previous circular tokamak simulations, and are in agreement with tokamak experiments in the RFX-mod and DIII-D devices. Sawtooth mitigation via MPs has also been observed in reversed-field pinch simulations and experiments. The effect of MPs on the stochastization of the edge magnetic field is also discussed., Comment: Proceeding paper of the 7th IAEA Technical Meeting on 'Theory of Plasmas Instabilities', Frascati (Italy), March 4-6, 2015. This manuscript will be published on the conference website http://www.iaeatm-inst2015.enea.it/

Published
2016

5. Impact Of A Uniform Plasma Resistivity In MHD Modelling Of Helical Solutions For The Reversed Field Pinch Dynamo

Author

Bonfiglio, D., Cappello, S., and Escande, D. F.

Subjects
Physics - Plasma Physics
Abstract

Till now the magnetohydrodynamic (MHD) simulation of the reversed field pinch (RFP) has been performed by assuming axis-symmetric radial time independent dissipation profiles. In helical states this assumption is not correct since these dissipations should be flux functions, and should exhibit a helical symmetry as well. Therefore more correct simulations should incorporate self-consistent dissipation profiles. As a first step in this direction, the case of uniform dissipation profiles was considered by using the 3D nonlinear visco-resistive MHD code SpeCyl. It is found that a flattening of the resistivity profile results in the reduction of the dynamo action, which brings to marginally-reversed or even non-reversed equilibrium solutions. The physical origin of this result is discussed in relation to the electrostatic drift explanation of the RFP dynamo. This sets constraints on the functional choice of dissipations in future self-consistent simulations., Comment: Proceeding paper of the 13th International Congress on Plasma Physics, Kiev, May 22-26, 2006. This manuscript has been submitted to arXiv because it is no longer present in the conference website http://www.icpp2006.kiev.ua/

Published
2016

6. N-body description of Debye shielding and Landau damping

Author

Escande, D. F., Doveil, F., and Elskens, Yves

Subjects
Physics - Plasma Physics, Physics - Classical Physics
Abstract

This paper brings further insight into the recently published N-body description of Debye shielding and Landau damping [Escande D F, Elskens Y and Doveil F 2014 Plasma Phys. Control. Fusion 57 025017]. Its fundamental equation for the electrostatic potential is derived in a simpler and more rigorous way. Various physical consequences of the new approach are discussed, and this approach is compared with the seminal one by Pines and Bohm [Pines D and Bohm D 1952 Phys. Rev. 85 338--353]., Comment: invited talk to 42nd EPS conference on plasma physics (Lisbon, 2015), submitted to Plasma Physics and Controlled Fusion

Published
2015
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7. Vlasov equation and $N$-body dynamics - How central is particle dynamics to our understanding of plasmas?

Author

Elskens, Yves, Escande, D. F., and Doveil, Fabrice

Subjects
Physics - Plasma Physics, Mathematical Physics
Abstract

Difficulties in founding microscopically the Vlasov equation for Coulomb-interacting particles are recalled for both the statistical approach (BBGKY hierarchy and Liouville equation on phase space) and the dynamical approach (single empirical measure on one-particle $(\mathbf{r},\mathbf{v})$-space). The role of particle trajectories (characteristics) in the analysis of the partial differential Vlasov--Poisson system is stressed. Starting from many-body dynamics, a direct derivation of both Debye shielding and collective behaviour is sketched., Comment: revTeX, 15 pp

Published
2014
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8. Perturbative transport experiments: to what extent do they really probe microscopic transport?

Author

Sattin, F., Escande, D. F., Auriemma, F., Urso, G., and Terranova, D.

Subjects
Physics - Plasma Physics
Abstract

Experiments featuring fast heat propagation, or so called "non-local" transport, were a puzzle for almost two decades. However recently it was shown, and it is recalled here, that a collective ideal MHD response of the plasma provides a quantitative agreement with these experiments, whereas transport plays just a secondary role. Then this work reviews the algebraic approach to transport data inversion that provides a formally exact solution, as well as a quantitative assessment of error bars, limited to periodic signals. Conversely, standard transport reconstructions are shown to sometimes fail to match the exact solution. The adoption of automated global search algorithms based upon Genetic Algorithms is bound to greatly increase the probability of finding optimal solutions. Finally, the standard methods of reconstruction infer the diffusivity D and pinch V by matching experimental data against those simulated by transport codes. These methods do not warrant the validity neither of the underlying models of transport, nor of the reconstructed D(r) and V(r), even when the results look reasonable., Comment: To be submitted to Plasma Physics and Controlled Fusion, cluster issue on "Physics-based Optimization of Plasma Diagnostic Information"

Published
2014

9. Alfvenic propagation: a key to nonlocal effects in magnetized plasmas

Author

Sattin, F. and Escande, D. F.

Subjects
Physics - Plasma Physics
Abstract

A long standing puzzle in fusion research comes from experiments where a sudden peripheral electron temperature perturbation is accompanied by an almost simultaneous opposite change in central temperature, in a way incompatible with local transport models. This paper shows these experiments and similar ones are fairly well quantitatively reproduced, when induction effects are incorporated in the total plasma response, alongside standard local diffusive transport, as suggested in earlier work [V.D. Pustovitov, Plasma Phys. Control. Fusion {\bf 54}, 124036 (2012)]., Comment: After the publication of the paper we became aware of a fundamental error in the normalization of our equations. While at some places, plasma pressure was normalized to the magnetic energy density, at other places, plasma pressure and the plasma pressure source were normalized to the {\it equilibrium} plasma pressure. This involves that a $\beta$ factor was missing in some of the equations. By an unfortunate coincidence the different sources of error largely masked each other in the final results, thereby allowing the model to provide seemingly accurate conclusions. The correction of this error implies that the alleged MHD effects are smaller by a factor $\beta$, and cannot account for the phenomenology observed. This invalidates our conclusions

Published
2013
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10. Estimate of convection-diffusion coefficients from modulated perturbative experiments as an inverse problem

Author

Sattin, F., Escande, D. F., Camenen, Y., Salmi, A. T., and Tala, T.

Subjects
Physics - Plasma Physics
Abstract

The estimate of coefficients of the Convection-Diffusion Equation (CDE) from experimental measurements belongs in the category of inverse problems, which are known to come with issues of ill-conditioning or singularity. Here we concentrate on a particular class that can be reduced to a linear algebraic problem, with explicit solution. Ill-conditioning of the problem corresponds to the vanishing of one eigenvalue of the matrix to be inverted. The comparison with algorithms based upon matching experimental data against numerical integration of the CDE sheds light on the accuracy of the parameter estimation procedures, and suggests a path for a more precise assessment of the profiles and of the related uncertainty. Several instances of the implementation of the algorithm to real data are presented., Comment: Extended version of an invited talk presented at the 2012 EPS Conference. To appear in Plasma Physics and Controlled Fusion

Published
2012
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11. Calculation of transport coefficient profiles in modulation experiments as an inverse problem

Author

Escande, D. F. and Sattin, F.

Subjects
Physics - Plasma Physics
Abstract

The calculation of transport profiles from experimental measurements belongs in the category of inverse problems which are known to come with issues of ill-conditioning or singularity. A reformulation of the calculation, the matricial approach, is proposed for periodically modulated experiments, within the context of the standard advection-diffusion model where these issues are related to the vanishing of the determinant of a 2x2 matrix. This sheds light on the accuracy of calculations with transport codes, and provides a path for a more precise assessment of the profiles and of the related uncertainty., Comment: V2: two typos corrected

Published
2011
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13. When can Fokker-Planck Equation describe anomalous or chaotic transport?

Author

Escande, D. F. and Sattin, F.

Subjects
Physics - Plasma Physics
Abstract

The Fokker-Planck Equation, applied to transport processes in fusion plasmas, can model several anomalous features, including uphill transport, scaling of confinement time with system size, and convective propagation of externally induced perturbations. It can be justified for generic particle transport provided that there is enough randomness in the Hamiltonian describing the dynamics. Then, except for 1 degree-of-freedom, the two transport coefficients are largely independent. Depending on the statistics of interest, the same dynamical system may be found diffusive or dominated by its L\'{e}vy flights., Comment: 4 pages. Accepted in Physical Review Letters. V2: only some minor changes

Published
2007
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14. Rigorous approach to the nonlinear saturation of the tearing mode in cylindrical and slab geometry

Author

Arcis, N., Escande, D. F., and Ottaviani, M.

Subjects
Physics - Plasma Physics
Abstract

The saturation of the tearing mode instability is described within the standard framework of reduced magnetohydrodynamics (RMHD) in the case of an $r$-dependent or of a uniform resistivity profile. Using the technique of matched asymptotic expansions, where the perturbation parameter is the island width $w$, the problem can be solved in two ways: with the so-called flux coordinate method, which is based on the fact that the current profile is a flux function, and with a new perturbative method that does not use this property. The latter is applicable to more general situations where an external forcing or a sheared velocity profile are involved. The calculation provides a new relationship between the saturated island width and the $\Delta '$ stability parameter that involves a $\ln{w/w_{0}}$ term, where $w_{0}$ is a nonlinear scaling length that was missing in previous work. It also yields the modification of the equilibrium magnetic flux function.

Published
2006
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15. Perturbative approach to the nonlinear saturation of the tearing mode for any current gradient

Author

Arcis, N., Escande, D. F., and Ottaviani, M.

Subjects
Physics - Plasma Physics
Abstract

Within the traditional frame of reduced MHD, a new rigorous perturbation expansion provides the equation ruling the nonlinear growth and saturation of the tearing mode for any current gradient. The small parameter is the magnetic island width w. For the first time, the final equation displays at once terms of order w ln(1/w) and w which have the same magnitude for practical purposes; two new O(w) terms involve the current gradient. The technique is applicable to the case of an external forcing. The solution for a static forcing is computed explicitly and it exhibits three physical regimes., Comment: 4 pages, submitted to Physical Review Letters

Published
2005

17. Quasilinear diffusion for the chaotic motion of a particle in a set of longitudinal waves

Author

Escande, D. F. and Elskens, Y.

Subjects
Physics - Plasma Physics, Condensed Matter - Statistical Mechanics, Nonlinear Sciences - Chaotic Dynamics
Abstract

The rigorous analytical calculation of the diffusion coefficient is performed for the chaotic motion of a particle in a set of longitudinal waves with random phases and large amplitudes (~ A). A first step proves the existence of a quasilinear diffusion on a time scale ~ A^{-2/3} \ln A. A second step uses this property to extend the result to asymptotic times by introducing the conditional probability distribution of position and velocity of an orbit at a given time when they are known at a previous time., Comment: 5 pages LaTeX - 14th Marian Smoluchowski Symposium on Statistical Physics: Fundamentals and Applications, Zakopane, Poland, September 9-14, 2001 ; typos removed

Published
2001

22. Large scale structures in kinetic plasma turbulence

Author

Escande, D. F., Araki, H., editor, Ehlers, J., editor, Hepp, K., editor, Jaffe, R. L., editor, Kippenhahn, R., editor, Ruelle, D., editor, Weidenmüller, H. A., editor, Wess, J., editor, Zittartz, J., editor, Beiglböck, W., editor, Fournier, Jean-Daniel, editor, and Sulem, Pierre-Louis, editor

Published
1991
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24. Self-organized helical equilibria as a new paradigm for ohmically heated fusion plasmas

Author

Lorenzini, R., Martines, E., Piovesan, P., Terranova, D., Zanca, P., Zuin, M., Alfier, A., Bonfiglio, D., Bonomo, F., Canton, A., Cappello, S., Carraro, L., Cavazzana, R., Escande, D. F., Fassina, A., Franz, P., Gobbin, M., Innocente, P., Marrelli, L., Pasqualotto, R., Puiatti, M. E., Spolaore, M., Valisa, M., Vianello, N., Martin, P., Apolloni, L., Adamek, J., Agostini, M., Annibaldi, S. V., Antoni, V., Auriemma, F., Barana, O., Baruzzo, M., Bettini, P., Bolzonella, T., Brombin, M., Brotankova, J., Buffa, A., Buratti, P., Cavinato, M., Chapman, B. E., Chitarin, G., Bello, S. D., Lorenzi, A. D., Masi, G. D., Ferro, A., Gaio, E., Gazza, E., Giudicotti, L., Gnesotto, F., Grando, L., Guazzotto, L., Guo, S. C., Igochine, V., Liu, Y. Q., Luchetta, A., Manduchi, G., Marchiori, G., Marcuzzi, D., Martini, S., McCollam, K., Milani, F., Moresco, M., Novello, L., Ortolani, S., Paccagnella, R., Peruzzo, S., Piovan, R., Piron, L., Pizzimenti, A., Pomaro, N., Predebon, I., Reusch, J. A., Rostagni, G., Rubinacci, G., Sarff, J. S., Sattin, F., Scarin, P., Serianni, G., Sonato, P., Spada, E., Soppelsa, A., Spagnolo, S., Spizzo, G., Taliercio, C., Toigo, V., Villone, F., White, R. B., Yadikin, D., Zaccaria, P., Zamengo, A., Zaniol, B., Zanotto, L., Zilli, E., Zohm, H., Zuin, M. Z., Lorenzini, R., Martines, E., Piovesan, P., Terranova, D., Zanca, P., Zuin, M., Alfier, A., Bonfiglio, D., Bonomo, F., Canton, A., Cappello, S., Carraro, L., Cavazzana, R., Escande, D. F., Fassina, A., Franz, P., Gobbin, M., Innocente, P., Marrelli, L., Pasqualotto, R., Puiatti, M. E., Spolaore, M., Valisa, M., Vianello, N., Martin, P., Apolloni, L., Adamek, J., Agostini, M., Annibaldi, S. V., Antoni, V., Auriemma, F., Barana, O., Baruzzo, M., Bettini, P., Bolzonella, T., Brombin, M., Brotankova, J., Buffa, A., Buratti, P., Cavinato, M., Chapman, B. E., Chitarin, G., Bello, S. D., Lorenzi, A. D., Masi, G. D., Ferro, A., Gaio, E., Gazza, E., Giudicotti, L., Gnesotto, F., Grando, L., Guazzotto, L., Guo, S. C., Igochine, V., Liu, Y. Q., Luchetta, A., Manduchi, G., Marchiori, G., Marcuzzi, D., Martini, S., Mccollam, K., Milani, F., Moresco, M., Novello, L., Ortolani, S., Paccagnella, R., Peruzzo, S., Piovan, R., Piron, L., Pizzimenti, A., Pomaro, N., Predebon, I., Reusch, J. A., Rostagni, G., Rubinacci, G., Sarff, J. S., Sattin, F., Scarin, P., Serianni, G., Sonato, P., Spada, E., Soppelsa, A., Spagnolo, S., Spizzo, G., Taliercio, C., Toigo, V., Villone, F., White, R. B., Yadikin, D., Zaccaria, P., Zamengo, A., Zaniol, B., Zanotto, L., Zilli, E., Zohm, H., Zuin, M. Z., Lorenzini, R, Martines, E, Piovesan, P, Terranova, D, Zanca, P, Zuin, M, Alfier, A, Bonfiglio, D, Bonomo, F, Canton, A, Cappello, S, Carraro, L, Cavazzana, R, Escande, D, Fassina, A, Franz, P, Gobbin, M, Innocente, P, Marrelli, L, Pasqualotto, R, Puiatti, M, Spolaore, M, Valisa, M, Vianello, N, and Martin, P

Subjects
Physics, quasi-single-helicity, Toroid, Tokamak, Fusion plasma, General Physics and Astronomy, Magnetic confinement fusion, reversed field pinch, Mechanics, Plasma, Fusion power, Instability, law.invention, Physics::Plasma Physics, law, RFP, Pinch, QSH, Atomic physics
Abstract

In the quest for new energy sources, the research on controlled thermonuclear fusion has been boosted by the start of the construction phase of the International Thermonuclear Experimental Reactor (ITER). ITER is based on the tokamak magnetic configuration, which is the best performing one in terms of energy confinement. Alternative concepts are however actively researched, which in the long term could be considered for a second generation of reactors. Here, we show results concerning one of these configurations, the reversed-field pinch (RFP). By increasing the plasma current, a spontaneous transition to a helical equilibrium occurs, with a change of magnetic topology. Partially conserved magnetic flux surfaces emerge within residual magnetic chaos, resulting in the onset of a transport barrier. This is a structural change and sheds new light on the potential of the RFP as the basis for a low-magnetic-field ohmic fusion reactor. © 2009 Macmillan Publishers Limited.

Published
2009

25. A power-balance model of the density limit in fusion plasmas: application to the L-mode tokamak

Author

Zanca, P., Sattin, F., Escande, D. F., Abduallev, S., Abhangi, M., Abreu, P., Afzal, M., Aggarwal, K. M., Ahlgren, T., Ahn, J. H., Aho-Mantila, L., Aiba, N., Airila, M., Albanese, R., Aldred, V., Alegre, D., Alessi, E., Aleynikov, P., Alfier, A., Alkseev, A., Allinson, M., Alper, B., Alves, E., Ambrosino, G., Ambrosino, R., Amicucci, L., Amosov, V., Sunden, E. Andersson, Angelone, M., Anghel, M., Angioni, C., Appel, L., Appelbee, C., Arena, P., Ariola, M., Arnichand, H., Arshad, S., Ash, A., Ashikawa, N., Aslanyan, V., Asunta, O., Auriemma, F., Austin, Y., Avotina, L., Axton, M. D., Ayres, C., Bacharis, M., Baciero, A., Baiao, D., Bailey, S., Baker, A., Balboa, I., Balden, M., Balshaw, N., Bament, R., Banks, J. W., Baranov, Y. F., Barnard, M. A., Barnes, D., Barnes, M., Barnsley, R., Wiechec, A. Baron, Orte, L. Barrera, Baruzzo, M., Basiuk, V., Bassan, M., Bastow, R., Batista, A., Batistoni, P., Baughan, R., Bauvir, B., Baylor, L., Bazylev, B., Beal, J., Beaumont, P. S., Beckers, M., Beckett, B., Becoulet, A., Bekris, N., Beldishevski, M., Bell, K., Belli, F., Bellinger, M., Belonohy, E., Ben Ayed, N., Benterman, N. A., Bergsaker, H., Bernardo, J., Bernert, M., Berry, M., Bertalot, L., Besliu, C., Beurskens, M., Bieg, B., Bielecki, J., Biewer, T., Bigi, M., Bilkova, P., Binda, F., Bisoffi, A., Bizarro, J. P. S., Bjorkas, C., Blackburn, J., Blackman, K., Blackman, T. R., Blanchard, P., Blatchford, P., Bobkov, V., Boboc, A., Bodnar, G., Bogar, O., Bolshakova, I., Bolzonella, T., Bonanomi, N., Bonelli, F., Boom, J., Booth, J., Borba, D., Borodin, D., Borodkina, I., Botrugno, A., Bottereau, C., Boulting, P., Bourdelle, C., Bowden, M., Bower, C., Bowman, C., Boyce, T., Boyd, C., Boyer, H. J., Bradshaw, J. M. A., Braic, V., Bravanec, R., Breizman, B., Bremond, S., Brennan, P. D., Breton, S., Brett, A., Brezinsek, S., Bright, M. D. J., Brix, M., Broeckx, W., Brombin, M., Broslawski, A., Brown, D. P. D., Brown, M., Bruno, E., Bucalossi, J., Buch, J., Buchanan, J., Buckley, M. A., Budny, R., Bufferand, H., Bulman, M., Bulmer, N., Bunting, P., Buratti, P., Burckhart, A., Buscarino, A., Busse, A., Butler, N. K., Bykov, I., Byrne, J., Cahyna, P., Calabro, G., Calvo, I., Camenen, Y., Camp, P., Campling, D. C., Cane, J., Cannas, B., Capel, A. J., Card, P. J., Cardinali, A., Carman, P., Carr, M., Carralero, D., Carraro, L., Carvalho, B. B., Carvalho, I., Carvalho, P., Casson, F. J., Castaldo, C., Catarino, N., Caumont, J., Causa, F., Cavazzana, R., Cave-Ayland, K., Cavinato, M., Cecconello, M., Ceccuzzi, S., Cecil, E., Cenedese, A., Cesario, R., Challis, C. D., Chandler, M., Chandra, D., Chang, C. S., Chankin, A., Chapman, I. T., Chapman, S. C., Chernyshova, M., Chitarin, G., Ciraolo, G., Ciric, D., Citrin, J., Clairet, F., Clark, E., Clark, M., Clarkson, R., Clatworthy, D., Clements, C., Cleverly, M., Coad, J. P., Coates, P. A., Cobalt, A., Coccorese, V., Cocilovo, V., Coda, S., Coelho, R., Coenen, J. W., Coffey, I., Colas, L., Collins, S., Conka, D., Conroy, S., Conway, N., Coombs, D., Cooper, D., Cooper, S. R., Corradino, C., Corre, Y., Corrigan, G., Cortes, S., Coster, D., Couchman, A. S., Cox, M. P., Craciunescu, T., Cramp, S., Craven, R., Crisanti, F., Croci, G., Croft, D., Crombe, K., Crowe, R., Cruz, N., Cseh, G., Cufar, A., Cullen, A., Curuia, M., Czarnecka, A., Dabirikhah, H., Dalgliesh, P., Dalley, S., Dankowski, J., Darrow, D., Davies, O., Davis, W., Day, C., Day, I. E., De Bock, M., de Castro, A., de la Cal, E., de la Luna, E., De Masi, G., de Pablos, J. L., De Temmerman, G., De Tommasi, G., de Vries, P., Deakin, K., Deane, J., Agostini, F. Degli, Dejarnac, R., Delabie, E., den Harder, N., Dendy, R. O., Denis, J., Denner, P., Devaux, S., Devynck, P., Di Maio, F., Di Siena, A., Di Troia, C., Dinca, P., D'Inca, R., Ding, B., Dittmar, T., Doerk, H., Doerner, R. P., Donne, T., Dorling, S. E., Dormido-Canto, S., Doswon, S., Douai, D., Doyle, P. T., Drenik, A., Drewelow, P., Drews, P., Duckworth, Ph., Dumont, R., Dumortier, P., Dunai, D., Dunne, M., Duran, I., Durodie, F., Dutta, P., Duval, B. P., Dux, R., Dylst, K., Dzysiuk, N., Edappala, P. V., Edmond, J., Edwards, A. M., Edwards, J., Eich, Th., Ekedahl, A., El-Jorf, R., Elsmore, C. G., Enachescu, M., Ericsson, G., Eriksson, F., Eriksson, J., Eriksson, L. G., Esposito, B., Esquembri, S., Esser, H. G., Esteve, D., Evans, B., Evans, G. E., Evison, G., Ewart, G. D., Fagan, D., Faitsch, M., Falie, D., Fanni, A., Fasoli, A., Faustin, J. M., Fawlk, N., Fazendeiro, L., Fedorczak, N., Felton, R. C., Fenton, K., Fernades, A., Fernandes, H., Ferreira, J., Fessey, J. A., Fevrier, O., Ficker, O., Field, A., Fietz, S., Figueiredo, A., Figueiredo, J., Fil, A., Finburg, P., Firdaouss, M., Fischer, U., Fittill, L., Fitzgerald, M., Flammini, D., Flanagan, J., Fleming, C., Flinders, K., Fonnesu, N., Fontdecaba, J. M., Formisano, A., Forsythe, L., Fortuna, L., Fortuna-Zalesna, E., Fortune, M., Foster, S., Franke, T., Franklin, T., Frasca, M., Frassinetti, L., Freisinger, M., Fresa, R., Frigione, D., Fuchs, V., Fuller, D., Futatani, S., Fyvie, J., Gal, K., Galassi, D., Galazka, K., Galdon-Quiroga, J., Gallagher, J., Gallart, D., Galvao, R., Gao, X., Gao, Y., Garcia, J., Garcia-Carrasco, A., Garcia-Munoz, M., Gardarein, J. -L., Garzotti, L., Gaudio, P., Gauthier, E., Gear, D. F., Gee, S. J., Geiger, B., Gelfusa, M., Gerasimov, S., Gervasini, G., Gethins, M., Ghani, Z., Ghate, M., Gherendi, M., Giacalone, J. C., Giacomelli, L., Gibson, C. S., Giegerich, T., Gil, C., Gil, L., Gilligan, S., Gin, D., Giovannozzi, E., Girardo, J. B., Giroud, C., Giruzzi, G., Gloeggler, S., Godwin, J., Goff, J., Gohil, P., Goloborod'ko, V., Gomes, R., Goncalves, B., Goniche, M., Goodliffe, M., Goodyear, A., Gorini, G., Gosk, M., Goulding, R., Goussarov, A., Gowland, R., Graham, B., Graham, M. E., Graves, J. P., Grazier, N., Grazier, P., Green, N. R., Greuner, H., Grierson, B., Griph, F. S., Grisolia, C., Grist, D., Groth, M., Grove, R., Grundy, C. N., Grzonka, J., Guard, D., Guerard, C., Guillemaut, C., Guirlet, R., Gurl, C., Utoh, H. H., Hackett, L. J., Hacquin, S., Hagar, A., Hager, R., Hakola, A., Halitovs, M., Hall, S. J., Cook, S. P. Hallworth, Hamlyn-Harris, C., Hammond, K., Harrington, C., Harrison, J., Harting, D., Hasenbeck, F., Hatano, Y., Hatch, D. R., Haupt, T. D. V., Hawes, J., Hawkes, N. C., Hawkins, J., Hawkins, P., Haydon, P. W., Hayter, N., Hazel, S., Heesterman, P. J. L., Heinola, K., Hellesen, C., Hellsten, T., Helou, W., Hemming, O. N., Hender, T. C., Henderson, M., Henderson, S. S., Henriques, R., Hepple, D., Hermon, G., Hertout, P., Hidalgo, C., Highcock, E. G., Hill, M., Hillairet, J., Hillesheim, J., Hillis, D., Hizanidis, K., Hjalmarsson, A., Hobirk, J., Hodille, E., Hogben, C. H. A., Hogeweij, G. M. D., Hollingsworth, A., Hollis, S., Homfray, D. A., Horacek, J., Hornung, G., Horton, A. R., Horton, L. D., Horvath, L., Hotchin, S. P., Hough, M. R., Howarth, P. J., Hubbard, A., Huber, A., Huber, V., Huddleston, T. M., Hughes, M., Huijsmans, G. T. A., Hunter, C. L., Huynh, P., Hynes, A. M., Iglesias, D., Imazawa, N., Imbeaux, F., Imrisek, M., Incelli, M., Innocente, P., Irishkin, M., Ivanova-Stanik, I., Jachmich, S., Jacobsen, A. S., Jacquet, P., Jansons, J., Jardin, A., Jarvinen, A., Jaulmes, F., Jednorog, S., Jenkins, I., Jeong, C., Jepu, I., Joffrin, E., Johnson, R., Johnson, T., Johnston, Jane, Joita, L., Jones, G., Jones, T. T. C., Hoshino, K. K., Kallenbach, A., Kamiya, K., Kaniewski, J., Kantor, A., Kappatou, A., Karhunen, J., Karkinsky, D., Karnowska, I., Kaufman, M., Kaveney, G., Kazakov, Y., Kazantzidis, V., Keeling, D. L., Keenan, T., Keep, J., Kempenaars, M., Kennedy, C., Kenny, D., Kent, J., Kent, O. N., Khilkevich, E., Kim, H. T., Kim, H. S., Kinch, A., King, C., King, D., King, R. F., Kinna, D. 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J., Lehmann, J., Lehnen, M., Leichtle, D., Leichuer, P., Leipold, F., Lengar, I., Lennholm, M., Lerche, E., Lescinskis, A., Lesnoj, S., Letellier, E., Leyland, M., Leysen, W., Li, L., Liang, Y., Likonen, J., Linke, J., Linsmeier, Ch., Lipschultz, B., Liu, G., Liu, Y., Lo Schiavo, V. P., Loarer, T., Loarte, A., Lobel, R. C., Lomanowski, B., Lomas, P. J., Lonnroth, J., Lopez, J. M., Lopez-Razola, J., Lorenzini, R., Losada, U., Lovell, J. J., Loving, A. B., Lowry, C., Luce, T., Lucock, R. M. A., Lukin, A., Luna, C., Lungaroni, M., Lungu, C. P., Lungu, M., Lunniss, A., Lupelli, I., Lyssoivan, A., Macdonald, N., Macheta, P., Maczewa, K., Magesh, B., Maget, P., Maggi, C., Maier, H., Mailloux, J., Makkonen, T., Makwana, R., Malaquias, A., Malizia, A., Manas, P., Manning, A., Manso, M. E., Mantica, P., Mantsinen, M., Manzanares, A., Maquet, Ph., Marandet, Y., Marcenko, N., Marchetto, C., Marchuk, O., Marinelli, M., Marinucci, M., Markovic, T., Marocco, D., Marot, L., Marren, C. A., Marshal, R., Martin, A., Martin, Y., Martin de Aguilera, A., Martinez, F. J., Martin-Solis, J. R., Martynova, Y., Maruyama, S., Masiello, A., Maslov, M., Matejcik, S., Mattei, M., Matthews, G. F., Maviglia, F., Mayer, M., Mayoral, M. L., May-Smith, T., Mazon, D., Mazzotta, C., McAdams, R., McCarthy, P. J., McClements, K. G., McCormack, O., McCullen, P. A., McDonald, D., McIntosh, S., McKean, R., McKehon, J., Meadows, R. C., Meakins, A., Medina, F., Medland, M., Medley, S., Meigh, S., Meigs, A. G., Meisl, G., Meitner, S., Meneses, L., Menmuir, S., Mergia, K., Merrigan, I. R., Mertens, Ph., Meshchaninov, S., Messiaen, A., Meyer, H., Mianowski, S., Michling, R., Middleton-Gear, D., Miettunen, J., Militello, F., Militello-Asp, E., Miloshevsky, G., Mink, F., Minucci, S., Miyoshi, Y., Mlynar, J., Molina, D., Monakhov, I., Moneti, M., Mooney, R., Moradi, S., Mordijck, S., Moreira, L., Moreno, R., Moro, F., Morris, A. W., Morris, J., Moser, L., Mosher, S., Moulton, D., Murari, A., Muraro, A., Murphy, S., Asakura, N. N., Na, Y. S., Nabais, F., Naish, R., Nakano, T., Nardon, E., Naulin, V., Nave, M. F. F., Nedzelski, I., Nemtsev, G., Nespoli, F., Neto, A., Neu, R., Neverov, V. S., Newman, M., Nicholls, K. J., Nicolas, T., Nielsen, A. H., Nielsen, P., Nilsson, E., Nishijima, D., Noble, C., Nocente, M., Nodwell, D., Nordlund, K., Nordman, H., Nouailletas, R., Nunes, I., Oberkofler, M., Odupitan, T., Ogawa, M. T., O'Gorman, T., Okabayashi, M., Olney, R., Omolayo, O., O'Mullane, M., Ongena, J., Orsitto, F., Orszagh, J., Oswuigwe, B. I., Otin, R., Owen, A., Paccagnella, R., Pace, N., Pacella, D., Packer, L. W., Page, A., Pajuste, E., Palazzo, S., Pamela, S., Panja, S., Papp, P., Paprok, R., Parail, V., Park, M., Diaz, F. Parra, Parsons, M., Pasqualotto, R., Patel, A., Pathak, S., Paton, D., Patten, H., Pau, A., Pawelec, E., Soldan, C. Paz, Peackoc, A., Pearson, I. J., Pehkonen, S. -P., Peluso, E., Penot, C., Pereira, A., Pereira, R., Puglia, P. P. Pereira, von Thun, C. Perez, Peruzzo, S., Peschanyi, S., Peterka, M., Petersson, P., Petravich, G., Petre, A., Petrella, N., Petrzilka, V., Peysson, Y., Pfefferle, D., Philipps, V., Pillon, M., Pintsuk, G., Piovesan, P., Pires dos Reis, A., Piron, L., Pironti, A., Pisano, F., Pitts, R., Pizzo, F., Plyusnin, V., Pomaro, N., Pompilian, O. G., Pool, P. J., Popovichev, S., Porfiri, M. T., Porosnicu, C., Porton, M., Possnert, G., Potzel, S., Powell, T., Pozzi, J., Prajapati, V., Prakash, R., Prestopino, G., Price, D., Price, M., Price, R., Prior, P., Proudfoot, R., Pucella, G., Puglia, P., Puiatti, M. E., Pulley, D., Purahoo, K., Puetterich, Th., Rachlew, E., Rack, M., Ragona, R., Rainford, M. S. J., Rakha, A., Ramogida, G., Ranjan, S., Rapson, C. J., Rasmussen, J. J., Rathod, K., Ratta, G., Ratynskaia, S., Ravera, G., Rayner, C., Rebai, M., Reece, D., Reed, A., Refy, D., Regan, B., Regana, J., Reich, M., Reid, N., Reimold, F., Reinhart, M., Reinke, M., Reiser, D., Rendell, D., Reux, C., Reyes Cortes, S. D. A., Reynolds, S., Riccardo, V., Richardson, N., Riddle, K., Rigamonti, D., Rimini, F. G., Risner, J., Riva, M., Roach, C., Robins, R. J., Robinson, S. A., Robinson, T., Robson, D. W., Roccella, R., Rodionov, R., Rodrigues, P., Rodriguez, J., Rohde, V., Romanelli, F., Romanelli, M., Romanelli, S., Romazanov, J., Rowe, S., Rubel, M., Rubinacci, G., Rubino, G., Ruchko, L., Ruiz, M., Ruset, C., Rzadkiewicz, J., Saarelma, S., Sabot, R., Safi, E., Sagar, P., Saibene, G., Saint-Laurent, F., Salewski, M., Salmi, A., Salmon, R., Salzedas, F., Samaddar, D., Samm, U., Sandiford, D., Santa, P., Santala, M. I. K., Santos, B., Santucci, A., Sartori, F., Sartori, R., Sauter, O., Scannell, R., Schlummer, T., Schmid, K., Schmidt, V., Schmuck, S., Schneider, M., Schoepf, K., Schworer, D., Scott, S. D., Sergienko, G., Sertoli, M., Shabbir, A., Sharapov, S. E., Shaw, A., Shaw, R., Sheikh, H., Shepherd, A., Shevelev, A., Shumack, A., Sias, G., Sibbald, M., Sieglin, B., Silburn, S., Silva, A., Silva, C., Simmons, P. A., Simpson, J., Simpson-Hutchinson, J., Sinha, A., Sipila, S. K., Sips, A. C. C., Siren, P., Sirinelli, A., Sjostrand, H., Skiba, M., Skilton, R., Slabkowska, K., Slade, B., Smith, N., Smith, P. G., Smith, R., Smith, T. J., Smithies, M., Snoj, L., Soare, S., Solano, E. R., Somers, A., Sommariva, C., Sonato, P., Sopplesa, A., Sousa, J., Sozzi, C., Spagnolo, S., Spelzini, T., Spineanu, F., Stables, G., Stamatelatos, I., Stamp, M. F., Staniec, P., Stankunas, G., Stan-Sion, C., Stead, M. J., Stefanikova, E., Stepanov, I., Stephen, A. V., Stephen, M., Stevens, A., Stevens, B. D., Strachan, J., Strand, P., Strauss, H. R., Strom, P., Stubbs, G., Studholme, W., Subba, F., Summers, H. P., Svensson, J., Swiderski, L., Szabolics, T., Szawlowski, M., Szepesi, G., Suzuki, T. T., Tal, B., Tala, T., Talbot, A. R., Talebzadeh, S., Taliercio, C., Tamain, P., Tame, C., Tang, W., Tardocchi, M., Taroni, L., Taylor, D., Taylor, K. A., Tegnered, D., Telesca, G., Teplova, N., Terranova, D., Testa, D., Tholerus, E., Thomas, J., Thomas, J. D., Thomas, P., Thompson, A., Thompson, C. -A., Thompson, V. K., Thorne, L., Thornton, A., Thrysoe, A. S., Tigwell, P. A., Tipton, N., Tiseanu, I., Tojo, H., Tokitani, M., Tolias, P., Tomes, M., Tonner, P., Towndrow, M., Trimble, P., Tripsky, M., Tsalas, M., Tsavalas, P., Jun, D. Tskhakaya, Turner, I., Turner, M. M., Turnyanskiy, M., Tvalashvili, G., Tyrrell, S. G. J., Uccello, A., Ul-Abidin, Z., Uljanovs, J., Ulyatt, D., Urano, H., Uytdenhouwen, I., Vadgama, A. P., Valcarcel, D., Valentinuzzi, M., Valisa, M., Olivares, P. Vallejos, Valovic, M., Van De Mortel, M., Van Eester, D., Van Renterghem, W., van Rooij, G. J., Varje, J., Varoutis, S., Vartanian, S., Vasava, K., Vasilopoulou, T., Vega, J., Verdoolaege, G., Verhoeven, R., Verona, C., Rinati, G. Verona, Veshchev, E., Vianello, N., Vicente, J., Viezzer, E., Villari, S., Villone, F., Vincenzi, P., Vinyar, I., Viola, B., Vitins, A., Vizvary, Z., Vlad, M., Voitsekhovitch, I., Vondracek, P., Vora, N., Vu, T., Pires de Sa, W. W., Wakeling, B., Waldon, C. W. F., Walkden, N., Walker, M., Walker, R., Walsh, M., Wang, E., Wang, N., Warder, S., Warren, R. J., Waterhouse, J., Watkins, N. W., Watts, C., Wauters, T., Weckmann, A., Weiland, J., Weisen, H., Weiszflog, M., Wellstood, C., West, A. T., Wheatley, M. R., Whetham, S., Whitehead, A. M., Whitehead, B. D., Widdowson, A. M., Wiesen, S., Wilkinson, J., Williams, J., Williams, M., Wilson, A. R., Wilson, D. J., Wilson, H. R., Wilson, J., Wischmeier, M., Withenshaw, G., Withycombe, A., Witts, D. M., Wood, D., Wood, R., Woodley, C., Wray, S., Wright, J., Wright, J. C., Wu, J., Wukitch, S., Wynn, A., Xu, T., Yadikin, D., Yanling, W., Yao, L., Yavorskij, V., Yoo, M. G., Young, C., Young, D., Young, I. D., Young, R., Zacks, J., Zagorski, R., Zaitsev, F. S., Zanino, R., Zarins, A., Zastrow, K. D., Zerbini, M., Zhang, W., Zhou, Y., Zilli, E., Zoita, V., Zoletnik, S., Zychor, I., and Faculdade de Engenharia

Subjects
Nuclear and High Energy Physics, Física [Ciências exactas e naturais], Tokamak, Radiation, 01 natural sciences, 7. Clean energy, 010305 fluids & plasmas, law.invention, Física, Física, Physical sciences [Natural sciences], magnetohydrodynamics, transport, radiation, CONFINEMENT, OPERATION, Physics::Plasma Physics, Power Balance, law, Impurity, 0103 physical sciences, 010306 general physics, Physics, Physical sciences, Physics, Reversed field pinch, Mode (statistics), Condensed Matter Physics, Computational physics, operation, confinement, Magnetohydrodynamics, Stellarator
Abstract

A power-balance model, with radiation losses from impurities and neutrals, gives a unified description of the density limit (DL) of the stellarator, the L-mode tokamak, and the reversed field pinch (RFP). The model predicts a Sudo-like scaling for the stellarator, a Greenwald- like scaling, alpha I-p(8/9), for the RFP and the ohmic tokamak, a mixed scaling, alpha (PIp4/9)-I-4/9, for the additionally heated L-mode tokamak. In a previous paper (Zanca et al 2017 Nucl. Fusion 57 056010) the model was compared with ohmic tokamak, RFP and stellarator experiments. Here, we address the issue of the DL dependence on heating power in the L-mode tokamak. Experimental data from high-density disrupted L-mode discharges performed at JET, as well as in other machines, arc taken as a term of comparison. The model fits the observed maximum densities better than the pure Greenwald limit.

Published
2019

26. Progress in theoretical RFP studies: new stimulated helical regimes and similarities with tokamak and stellarator

Author

Bonfiglio D., Cappello S., Veranda M., Agostini M., Borgogno D., Chacon L., Escande D. F., Fassina A., Franz P., Gobbin M., Grasso D., Piovesan P., Predebon I., Puiatti M.E., Rubino G., Sattin F., and Zuin M.

Subjects
Physics::Plasma Physics
Abstract

Recent theoretical studies of the reversed-field pinch (RFP) have demonstrated the possibility of stimulating new quasi-single helicity (QSH) regimes by allowing a small helical deformation of the magnetic boundary. In particular, QSH states based on non-resonant helicities are predicted to be more resilient to magnetic stochasticity induced by secondary modes. This has motivated a series of successful experiments in the RFX-mod device with applied magnetic perturbations (MPs). We present here recent developments in nonlinear MHD modeling of RFP, highlighting aspects which share similarities between the RFP helical regimes, the tokamak sawtoothing and the stellarator. RFP helical configurations are obtained by applying small helical MPs with resonant (n 7) and non-resonant (n < 7) toroidal periodicities. MPs turn out to be a powerful tool for varying the helical equilibrium properties, like the helical safety factor or the magnetic well profile. The width of the region of conserved magnetic surfaces turns out to be the largest for the non-resonant case. By using a method to compute Lagrangian Coherent Structures, barriers to the diffusion of magnetic field lines are diagnosed in the weakly stochastic region surrounding the conserved helical core in numerical QSH states, providing a new tool for the study of Internal Transport Barriers formation at the transition to helical regimes in RFP experiments. Similar to the tokamak configuration, the sawtoothing dynamics of RFP plasmas is mitigated with the application of helical MPs. As for the edge region, the RFP is characterized by m = 0 island chains at the q = 0 reversal surface, which play a role similar to edge islands in tokamak and stellarator plasmas.

Published
2016

33. A multi-configuration fusion facility for three dimensional physics studies

Author

Piovesan, P., Bonfiglio, D., Auriemma, F., Bonomo, F., Carraro, L., Cavazzana, R., De Masi, G., Fassina, A., Franz, P., Gobbin, M., Marrelli, L., Martin, P., Martines, E., Momo, B., Piron, L., Valisa, M., Veranda, M., Vianello, N., Zaniol, B., Agostini, M., Baruzzo, M., Bolzonella, T., Canton, A., Cappello, S., Chacón, L., Ciaccio, G., Escande, D. F., Innocente, P., Lorenzini, R., Paccagnella, R., Puiatti, M. E., Scarin, P., Soppelsa, A., Spizzo, G., Spolaore, M., Terranova, D., Zanca, P., Zanotto, L., and Zuin, and M.

Published
2013

35. Nonlinear 3D MHD physics of the helical reversed-field pinch

Author

Bonfiglio D., Cappello S., Chacon L., Escande D. F., and Veranda M.

Subjects
Physics::Plasma Physics
Abstract

The main results from nonlinear 3D MHD simulations of the reversed-field pinch (RFP) will be presented, with a particular emphasis on the physics of the helical RFP states which are also experimentally observed, with the occurrence of internal transport barriers, in the RFX-mod device [1]. The recently benchmarked extended MHD code PIXIE3D [2] enables the inclusion of additional physics in the RFP simulations, like toroidal effects and the coupling with transport. The reduction of magnetic chaos in helical RFP states is confirmed by means of the field line tracing code NEMATO [3]. The evidence of magnetic shear reversal [4] and sheared plasma flows [5] in MHD simulations and their relation with the experimental observations will be also discussed. [1] R. Lorenzini et al., Nature Phys. 5 (2009) 570 [2] D. Bonfiglio et al., Phys. Plasmas 17 (2010) 082501 [3] D. Bonfiglio et al., J. Phys.: Conf. Ser. 260 (2010) 012003 [4] M. Gobbin et al., Phys. Rev. Lett. 106 (2011) 025001 [5] D. Bonfiglio et al., in Proceedings of the 37th EPS Conference on Plasma Physics (Dublin, 2010) http://ocs.ciemat.es/EPS2010PAP/pdf/O2.101.pdf

Published
2011

40. Magnetic order and confinement improvement in high-current regimes of RFX-mod with MHD feedback control

Author

Piovesan, P., Zuin, M., Alfier, A., Bonfiglio, D., Bonomo, F., Canton, A., Cappello, S., Carraro, L., Cavazzana, R., Escande, D. F., Fassina, Alessandro, Gobbin, M., Lorenzini, R., Marrelli, L., Martin, Piero, Martines, E., Pasqualotto, R., Puiatti, M. E., Spolaore, M., Valisa, M., Vianello, N., Zanca, P., THE RFX MOD TEAM, Piovesan, P, Zuin, M, Alfier, A, Bonfiglio, D, Bonomo, F, Canton, A, Cappello, S, Carraro, L, Cavazzana, R, Escande, D, Fassina, A, Gobbin, M, Lorenzini, R, Marrelli, L, Martin, P, Martines, E, Pasqualotto, R, Puiatti, M, Spolaore, M, Valisa, M, Vianello, N, and Zanca, P

Subjects
Physics, Nuclear and High Energy Physics, RFX-mod, Condensed matter physics, MHD, Magnetic confinement fusion, Plasma, reversed field pinch, Condensed Matter Physics, self-organization, Computational physics, Magnetic field, quasi-single helicity, Physics::Plasma Physics, numerical mhd simulation, transport, Pinch, RFP, Electron temperature, QSH, Magnetohydrodynamic drive, magnetic topology, Current (fluid), Magnetohydrodynamics
Abstract

The RFX-mod machine (Sonato et al 2003 Fusion Eng. Des. 66 161) recently achieved, for the first time in a reversed-field pinch, high plasma current up to 1.6 MA with good confinement. Magnetic feedback control of magnetohydrodynamic instabilities was essential to reach the goal. As the current is raised, the plasma spontaneously accesses a new helical state, starting from turbulent multi-helical conditions. Together with this raise, the ratio between the dominant and the secondary mode amplitudes increases in a continuous way. This brings a significant improvement in the magnetic field topology, with the formation of helical flux surfaces in the core. As a consequence, strong helical transport barriers with maximum electron temperature around 1 keV develop in this region. The energy confinement time increases by a factor of 4 with respect to the lower-current, multi-helical conditions. The properties of the new helical state scale favourably with the current, thus opening promising perspectives for the higher current experiments planned for the near future.

Published
2009

41. Overview of RFX-mod results

Author

Martin, Piero, Apolloni, L., Puiatti, M. E., Adamek, J., Agostini, M., Alfier, A., Annibaldi, S. V., Antoni, V., Auriemma, F., Barana, O., Baruzzo, M., Bettini, Paolo, Bolzonella, T., Bonfiglio, D., Bonomo, F., Brombin, M., Brotankova, J., Buffa, A., Buratti, P., Canton, A., Cappello, S., Carraro, L., Cavazzana, R., Cavinato, M., Chapman, B. E., Chitarin, Giuseppe, DAL BELLO, S., DE LORENZI, A., DE MASI, G., Escande, D. F., Fassina, Alessandro, Ferro, A., Franz, P., Gaio, E., Gazza, E., Giudicotti, Leonardo, Gnesotto, Francesco, Gobbin, M., Grando, L., Guazzotto, L., Guo, S. C., Igochine, V., Innocente, P., Liu, Y. Q., Lorenzini, R., Luchetta, A., Manduchi, G., Marchiori, G., Marcuzzi, D., Marrelli, L., Martini, S., Martines, E., Mccollam, K., Milani, F., Moresco, Maurizio, Novello, L., Ortolani, S., Paccagnella, R., Pasqualotto, R., Peruzzo, S., Piovan, R., Piovesan, P., Piron, L., Pizzimenti, A., Pomaro, N., Predebon, I., Reusch, J. A., Rostagni, G., Rubinacci, G., Sarff, J. S., Sattin, F., Scarin, P., Serianni, G., Sonato, Piergiorgio, Spada, E., Soppelsa, A., Spagnolo, S., Spolaore, M., Spizzo, G., Taliercio, C., Terranova, D., Toigo, V., Valisa, M., Vianello, N., Villone, F., Yadikin, D., Zaccaria, P., Zamengo, A., Zanca, P., Zaniol, B., Zanotto, L., Zilli, E., Zohm, H., and Zuin, M.

Published
2008

44. Impact of a uniform plasma resistivity in MHD modelling of helical solutions for the Reversed Field Pinch dynamo

Author

Bonfiglio, D., Cappello, S., and Escande, D. F.

Subjects
Plasma Physics (physics.plasm-ph), Physics::Plasma Physics, FOS: Physical sciences, Physics - Plasma Physics
Abstract

Till now the magnetohydrodynamic (MHD) simulation of the reversed field pinch (RFP) has been performed by assuming axis-symmetric radial time independent dissipation profiles. In helical states this assumption is not correct since these dissipations should be flux functions, and should exhibit a helical symmetry as well. Therefore more correct simulations should incorporate self-consistent dissipation profiles. As a first step in this direction, the case of uniform dissipation profiles was considered by using the 3D nonlinear visco-resistive MHD code SpeCyl. It is found that a flattening of the resistivity profile results in the reduction of the dynamo action, which brings to marginally-reversed or even non-reversed equilibrium solutions. The physical origin of this result is discussed in relation to the electrostatic drift explanation of the RFP dynamo. This sets constraints on the functional choice of dissipations in future self-consistent simulations., Proceeding paper of the 13th International Congress on Plasma Physics, Kiev, May 22-26, 2006. This manuscript has been submitted to arXiv because it is no longer present in the conference website http://www.icpp2006.kiev.ua/

Published
2006

45. Recent results from Real-Time active Control of MHD modes in RFX-mod

Author

Luchetta, A., Cavinato, M., Gaio, E., Grando, L., Manduchi, G., Marchiori, G., Pomaro, N., Soppelsa, A., Agostini, M., Alessi, C., Alfier, A., Antoni, V., Apolloni, L., Auriemma, F., PAOLO BETTINI, Bolzonella, T., Bonfiglio, D., Bonomo, F., Brombin, M., Buffa, Antonio, Canton, A., Cappello, S., Carraro, L., Cavazzana, R., Giuseppe Chitarin, Cravotta, A., Dal Bello, S., Lorenzi, A., Pasqual, L., Escande, D. F., Fassina, A., Franz, P., Gadani, G., Garzotti, L., Gazza, Erica, LEONARDO GIUDICOTTI, Gnesotto, Francesco, Gobbin, M., Guo, S. C., Innocente, P., Lorenzini, R., Malesani, G., Marcuzzi, D., Marrelli, L., PIERO MARTIN, Martini, S., Martines, E., Masiello, A., Milani, F., Moresco, M., Murari, A., Novello, L., Ortolani, S., Paccagnella, R., Pasqualotto, R., Peruzzo, S., Piovan, R., Piovesan, P., Pizzimenti, A., Puiatti, M. E., Rostagni, Giorgio, Sattin, F., Scarin, P., Serianni, G., piergiorgio sonato, Spada, E., Spizzo, G., Spolaore, M., Taccon, C., Taliercio, C., Terranova, D., Toigo, V., Valisa, M., Vianello, N., Zaccaria, P., Zanca, P., Zaniol, B., Zanotto, L., Zilli, Enrico, GIUSEPPE ZOLLINO, and Zuin, M.

Abstract

The paper focuses on the recent results achieved using at best the technology developed for the RFX-mod real time control system of MHD modes, which provides control features unique in the worldwide fusion experimental program. The paper aims at highlighting the successful technological aspects that have led to the outstanding scientific achievements obtained in the machine recent operation, including a dramatic increase in plasma duration and a significant decrease in magnetic perturbations. RFX-mod addresses the MHD mode control by acting on the magnetic field configuration at the boundary. The approach is not limited to the stabilization of Resistive Wall Modes (RWMs) in RFX-mod, but it also aims at acquiring an experimental knowledge on the MHD mode control that can be relevant for high beta discharges in tokamaks. To the purpose, an ad-hoc field correction coil system has been installed, consisting of 192 saddle coils covering the whole torus surface. The coils are arranged in 48 poloidal arrays, each made up of 4 equispaced coils. Each coil is fed independently. By means of this actuating system, magnetic field poloidal and toroidal harmonic components (m, n) can be generated with m=0, n=0 to 24 and m=1, n=-23 to 24. The control system is based on a modular hardware and software infrastructure, capable to fulfill the tight system requirements in terms of input/output channels (>700/>250), real time data flow (>2 Mbyte/s), computation capability (>1 GFLOP/s), and real time constraints. The control system, which has been extensively and routinely used in the operation of RFX-mod since the commissioning, provides a very powerful environment for interaction with MHD modes and for their control. Two basic control strategies have been developed: the Selective Virtual Shell (SVS) and the Mode Control (MC). The former aims at canceling all modes (Virtual Shell concept) except for selected preset ones (Selectivity concept). The Selectivity concept allows operating without interfering with the vertical equilibrium field (m=1, n=0), allows studying the growth of selected unstable RWMs, and facilitates producing Quasi-Single Helicity plasmas. The MC scheme aims at interacting with single or multiple modes. In this strategy, the regulators act directly on the modes by means of complex gains that can account for mode rotation.

Published
2006

46. Active MHD control experiments in RFX-mod

Author

Sergio, Ortolani, Agostini, the RFX team: M., Alessi, C., Alfier, A., Antoni, V., Apolloni, L., Auriemma, Fulvio, Bettini, Paolo, Bolzonella, T., Bonfiglio, D., Bonomo, Federica, Brombin, Matteo, Buffa, Antonio, Canton, A., Cappello, S., Carraro, L., Cavazzana, R., Cavinato, M., Chitarin, Giuseppe, Cravotta, A., Dal Bello, S., De Lorenzi, A., De Pasqual, L., Escande, D. F., Fassina, A, Franz, P., Gadani, G., Gaio, E., Garzotti, L., Gazza, E., Giudicotti, Leonardo, Gnesotto, Francesco, Gobbin, M., Grando, L., Guo, S. C., Innocente, P., Lorenzini, R., Luchetta, A., Malesani, Gaetano, Manduchi, G., Marchiori, G., Marcuzzi, D., Marrelli, L., Martin, Piero, Martines, E., Masiello, A., Milani, F., Moresco, Maurizio, Murari, A., Novello, L., Ortolani, S., Paccagnella, R., Pasqualotto, R., Peruzzo, S., Piovan, R., Piovesan, P., Pizzimenti, A., Pomaro, N., Puiatti, M. E., Rostagni, Giorgio, Sattin, F., Scarin, P., Serianni, G., Sonato, Piergiorgio, Spada, E., Soppelsa, Anton, Spizzo, G., Spolaore, M., Taccon, Cristiano, Taliercio, C., Terranova, D., Toigo, V., Valisa, M., Vianello, N., Zaccaria, P., Zanca, P., Zaniol, B., Zanotto, L., Zilli, E., Zollino, Giuseppe, and Zuin, M.

Subjects
Physics, Toroid, STABILITY, Field (physics), Reversed field pinch, business.industry, PLASMAS, Shell (structure), Magnetic confinement fusion, Torus, Mechanics, Condensed Matter Physics, Rotation, Optics, REVERSED-FIELD-PINCH, SINGLE, Nuclear Energy and Engineering, CONFIGURATIONS, Physics::Plasma Physics, Magnetohydrodynamics, business
Abstract

The RFX reversed field pinch experiment has been modified (RFX-mod) to address specific issues of active control of MHD instabilities. A thin shell (tau(Bv)similar to 50 ms) has replaced the old thick one (tau(Bv)similar to 500 ms) and 192 (4 poloidal x 48 toroidal) independently powered saddle coils surround the thin shell forming a cage completely covering the torus. This paper reports the results obtained during the first year of operation. The system has been used with various control scenarios including experiments on local radial field cancellation over the entire torus surface to mimic an ideal wall ('virtual shell') and on single and multiple mode feedback control. Successful virtual shell operation has been achieved leading to: a 3-fold increase in pulse length and well controlled 300 ms pulses(similar to 6 shell times) up to similar to 1MA plasma current; one order of magnitude reduction of the dominant radial field perturbations at the plasma edge and correspondingly 100% increase in global energy confinement time. Robust feedback stabilization of resistive wall modes has been demonstrated in conditions where rotation does not play a role and multiple unstable modes are present.

Published
2006

47. Modeling and Interpretation of MHD Active Control Experiments in RFX-mod

Author

Paccagnella, R., Terranova, D., Zanca, P., Team, Rfx, Agostini, M., Alessi, C., Alfier, A., Antoni, V., Apolloni, L., Auriemma, F., PAOLO BETTINI, Bolzonella, T., Bonfiglio, D., Bonomo, F., Brombin, M., Buffa, Antonio, Canton, A., Cappello, S., Carraro, L., Cavazzana, R., Cavinato, M., Giuseppe Chitarin, Cravotta, A., Dal Bello, S., Lorenzi, A., Pasqual, L., Escande, D. F., Fassina, A., Franz, P., Gadani, G., Gaio, E., Garzotti, L., Gazza, E., LEONARDO GIUDICOTTI, Gnesotto, Francesco, Gobbin, M., Grando, L., Guo, S. C., Innocente, P., Lorenzini, R., Luchetta, A., Malesani, G., Manduchi, G., Marchiori, G., Marcuzzi, D., Marrelli, L., PIERO MARTIN, Martines, E., Masiello, A., Milani, F., Moresco, M., Murari, A., Novello, L., Ortolani, S., Pasqualotto, R., Peruzzo, S., Piovan, R., Piovesan, P., Pizzimenti, A., Pomaro, N., Puiatti, M. E., Rostagni, Giorgio, Sattin, F., Scarin, P., Serianni, G., piergiorgio sonato, Spada, E., Soppelsa, A., Spizzo, G., Spolaore, M., Taccon, C., Taliercio, C., Toigo, V., Valisa, M., Vianello, N., Zaccaria, P., Zaniol, B., Zanotto, L., Zilli, Enrico, GIUSEPPE ZOLLINO, and Zuin, M.

Published
2006

48. First results on reversed field pinch plasmas with new magnetic boundary in the RFX-mod experiment

Author

Martini, S., Innocente, P., Agostini, M., Alfier, A., Antoni, V., Apolloni, L., Auriemma, F., Bagatin, M., Baker, W., Barana, O., Basso, F., Bettini, P., Bolzonella, T., Bonfiglio, D., Bonomo, F., Buffa, A., Canton, A., Cappello, S., Lorella Carraro, Cavazzana, R., Cavinato, M., Chitarin, G., Cravotta, A., Dal Bello, F. S., Dalla Palma, M., Lorenzi, A., Pasqual, L., Desideri, D., Escande, D. F., Franz, P., Gadani, G., Gaio, E., Garzotti, L., Gazza, E., Giudicotti, L., Gnesotto, F., Gobbin, M., Grando, L., Guo, S. C., Lorenzini, R., Luchetta, A., Malesani, G., Manduchi, G., Marchiori, G., Marcuzzi, D., Marrelli, L., Martin, P., Martines, E., Masiello, A., Milani, F., Moresco, M., Murari, A., Nielsen, P., Ortolani, S., Paccagnella, R., Pasqualotto, R., Peruzzo, S., Piovan, R., Piovesan, P., Predebon, I., Pomaro, N., Puiatti, M. E., Rostagni, G., Sattin, F., Scarin, P., Schmidt, V., Serianni, G., Sonato, P., Spada, E., Spizzo, G., Spolaore, M., Taccon, C., Taliercio, C., Terranova, D., Toigo, V., Valisa, M., Vianello, N., Zaccaria, P., Zanca, P., Zaniol, B., Zanotto, L., Zilli, E., Zollino, G., Zuin, M., Martini, S, Innocente, P, Agostini, M, Alfier, A, Antoni, V, Apolloni, L, Auriemma, F, Bagatin, M, Baker, W, Barana, O, Basso, F, Bettini, P, Bolzonella, T, Bonfiglio, D, Bonomo, F, Buffa, A, Canton, A, Cappello, S, Carraro, L, Cavazzana, R, Cavinato, M, Chitarin, G, Cravotta, A, Dal Bello, F, Dalla Palma, M, De Lorenzi, A, De Pasqual, L, Desideri, D, Escande, D, Franz, P, Gadani, G, Gaio, E, Garzotti, L, Gazza, E, Giudicotti, L, Gnesotto, F, Gobbin, M, Grando, L, Guo, S, Lorenzini, R, Luchetta, A, Malesani, G, Manduchi, G, Marchiori, G, Marcuzzi, D, Marrelli, L, Martin, P, Martines, E, Masiello, A, Milani, F, Moresco, M, Murari, A, Nielsen, P, Ortolani, S, Paccagnella, R, Pasqualotto, R, Peruzzo, S, Piovan, R, Piovesan, P, Predebon, I, Pomaro, N, Puiatti, M, Rostagni, G, Sattin, F, Scarin, P, Schmidt, V, Serianni, G, Sonato, P, Spada, E, Spizzo, G, Spolaore, M, Taccon, C, Taliercio, C, Terranova, D, Toigo, V, Valisa, M, Vianello, N, Zaccaria, P, Zanca, P, Zaniol, B, Zanotto, L, Zilli, E, Zollino, G, and Zuin, M

Subjects
RFX-mod, RFP, reversed field pinch
Published
2005

49. First Results of RFX-mod

Author

Agostinetti, P., Agostini, Matteo, Alfier, A., Antoni, V., Apolloni, L., Auriemma, Fulvio, Baker, W., Basso, Francesco, Bigi, M., Bettini, Paolo, Bolzonella, T., Bonfiglio, D., Bonomo, Federica, Buffa, Antonio, Canton, A., Cappello, S., Cavazzana, L. CARRARO R., Cavinato, M., Chitarin, Giuseppe, Cravotta, A., DAL BELLO, S., DALLA PALMA, M., DE LORENZI, A., DE PASQUAL, Lucia, Desideri, Daniele, Escande, D. F., Fiorentin, Pietro, Franz, P., Gadani, G., Gaio, E., Garzotti, L., Gazza, E., Giudicotti, Leonardo, Gnesotto, Francesco, Gobbin, Marco, Grando, L., Guo, S. C., Innocente, P., Lorenzini, R., Luchetta, A., Malesani, Gaetano, Manduchi, G., Marchiori, G., Marcuzzi, D., Marrelli, L., Martin, Piero, Martines, E., Martini, S., Masiello, A., Milani, F., Moresco, Maurizio, Murari, A., Nielsen, P., Ortolani, S., Paccagnella, R., Pasqualotto, R., Peruzzo, S., Piovan, R., Piovesan, P., Pomaro, N., Puiatti, M. E., Rostagni, Giorgio, Sattin, F., Scarin, P., Schmidt, V., Serianni, G., Sias, G., Sonato, Piergiorgio, Spada, E., Soppelsa, Anton, Spizzo, G., Spolaore, M., Taccon, Cristiano, Taliercio, C., Terranova, D., Testoni, P., Toigo, V., Valisa, M., Vianello, N., Zaccaria, P., Zanca, P., Zaniol, B., Zanotto, L., Zilli, Enrico, Zollino, Giuseppe, and Zuin, M.

Published
2005

50. Turbulent transport and plasma flow in the Reversed Field Pinch

Author

Antoni, Cavazzana, R., Martin, Piero, Serianni, G., Spada, E., Spolaore, M., Vianello, N., Drake, J. R., Bergsker, H., Brunsell, P. R., Cecconello, M., Regnoli, G., Alfier, A., Apolloni, L., Bagatin, Mario, Baker, W., Barana, O., Basso, Francesco, Bettella, D., Bettini, Paolo, Bolzonella, T., Bonfiglio, D., Buffa, Antonio, Canton, A., Cappello, S., Carraro, L., Cavinato, M., Chitarin, Giuseppe, Cravotta, A., D'Angelo, F., DAL BELLO, S., DALLA PALMA, M., DE LORENZI, A., DE PASQUAL, L., Desideri, Daniele, Escande, D. F., Fiorentin, P., Franz, P., Frassinetti, L., Gadani, G., Gaio, E., Garzotti, L., Gazza, E., Giudicotti, Leonardo, Gnesotto, Francesco, Grando, L., Guo, S. C., Innocente, P., Lorenzini, R., Luchetta, A., Malesani, Gaetano, Manduchi, G., Marchiori, G., Marcuzzi, D., Marrelli, L., Martin, P., Martini, S., Masiello, A., Milani, F., Moresco, Maurizio, Murari, A., Nielsen, P., Ortolani, S., Paccagnella, R., Pasqualotto, R., Peruzzo, S., Piovan, R., Piovesan, P., Pomaro, N., Puiatti, M. E., Rostagni, Giorgio, Sattin, F., Schmidt, V., Scarin, P., Sonato, Piergiorgio, Spizzo, G., Taliercio, C., Terranova, D., Toigo, V., Valisa, M., Zaccaria, N. P., Zanca, P., Zaniol, B., Zanotto, L., Zilli, Enrico, Zollino, Giuseppe, and Zuin, M.

Published
2004

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