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151. Review of recent EBT coupled ring-core stability theory

Author

Donald A. Spong

Subjects
Nuclear physics, Physics, Electron density, Coupling (physics), Distribution function, Compressibility, Electron temperature, Torus, Plasma, Instability, Computational physics
Abstract

During the past several years Elmo Bumpy Torus (EBT) stability calculations have evolved with respect to treatment of ring-core plasma coupling effects. This evolution began with recognition of the important role of ring compressibility and paramagnetic effects on core beta limits. Since then, models have continued to increase in sophistication, including ring-core frequency coupling, velocity space and hot electron distribution function effects, and radially dependent models. Some of these features have resulted in wide variations in predicted plasma performance limitations. A number of the models will be reviewed and assumptions to which they are particularly sensitive will be discussed.

Published
1981

152. Effects of isotropic alpha populations on tokamak ballooning stability

Author

D.J. Sigmar, K. T. Tsang, W. A. Cooper, Daniel E. Hastings, J. J. Ramos, and Donald A. Spong

Subjects
Physics, Tokamak, Plasma instability, law, Isotropy, Alpha particle, Atomic physics, Coupling (probability), Stability (probability), Ballooning, law.invention, Ballooning instability
Abstract

V 1 . INTRODUCTION 1 2 . BASIC En~)A'FIONS 5 3 . NUMERICAL SOL. U ' l ' l o N METHODS 24 4 . DISCUSSION OF r{!zw;rs 2 7 5 . CQNCLUS~ONS 3 4 REFERENCES 36

Published
1986

153. Effects of an alpha particle slowing-down distribution on tokamak ballooning modes

Author

D.J. Sigmar, Donald A. Spong, W. A. Cooper, and Daniel E. Hastings

Subjects
Physics, Range (particle radiation), Tokamak, Alpha particle, Charged particle, Ballooning, law.invention, Nuclear physics, Distribution function, Physics::Plasma Physics, law, Electron temperature, Atomic physics, Tokamak Fusion Test Reactor
Abstract

Energetic trapped alpha particles interact through their precessional drift with high-mode-number ballooning modes in tokamaks. Due to the energy dependence of the precessional drift, the consequences of this interaction depend on the form of the alpha distribution function. Results are compared here for two forms of alpha distribution: a Maxwellian and a slowing-down distribution. The latter has a significantly greater influence on ballooning stability because of the larger fraction of particles in the energy range of the drift resonance. Also, due to the dependence on the critical velocity (..alpha.. T/sub e/sup 1/2/), the stability boundaries and growth rates now are strong functions of the background electron temperature T/sub e/. Parameters typical of tokamak breakeven experiments such as the Tokamak Fusion Test Reactor (TFTR) are considered. 7 refs., 7 figs.

Published
1985

154. Curvature-driven instabilities in a hot-electron plasma: radial analysis

Author

Marshall N. Rosenbluth, Herbert L Berk, Donald A. Spong, and J. W. Van Dam

Subjects
Physics, Physics::Plasma Physics, law, Cyclotron, Electron temperature, Atmospheric-pressure plasma, Plasma, Magnetohydrodynamic drive, Curvature, Instability, Computational physics, Ion, law.invention
Abstract

The theory of unfavorable curvature-driven instabilities is developed for a plasma interacting with a hot electron ring whose drift frequencies are larger than the growth rates predicted from conventional magnetohydrodynamic theory. A z-pinch model is used to emphasize the radial structure of the problem. Stability criteria are obtained for the five possible modes of instability: the conventional hot electron interchange, a high-frequency hot electron interchange (at frequencies larger than the ion cyclotron frequency), a compressional instability, a background pressure-driven interchange, and an interacting pressure-driven interchange.

Published
1981

156. Ultra low aspect ratio stellarator or hybrid configurations

Author

A. S. Ware, J. C. Whitson, D. B. Batchelor, P. E. Moroz, Donald A. Spong, D. K. Lee, V. E. Lynch, Benjamin A. Carreras, S. P. Hirshman, and J. S. Tolliver

Subjects
Physics, Toroid, 020209 energy, General Engineering, 02 engineering and technology, 01 natural sciences, Aspect ratio (image), 010305 fluids & plasmas, law.invention, Bootstrap current, law, Hybrid system, Beta (plasma physics), 0103 physical sciences, 0202 electrical engineering, electronic engineering, information engineering, Statistical physics, Atomic physics, Current (fluid), Magnetohydrodynamics, Stellarator
Abstract

Novel concepts of an ultra-low-aspect-ratio stellarator system, called a Spherical Stellarator (SS), or a stellarator-tokamak hybrid system, called SMARTH (Small Aspect Ratio Toroidal Hybrid) are discussed for high-{beta} regimes of operation. Self-consistent analysis of the three-dimensional MHD equilibria with inductively driven plasma current or bootstrap current is presented. It is stressed that the bootstrap current in SS can be large and is flowing in such a direction that the rotational transform produced enhances the vacuum rotational transform. This feature increases the equilibrium {beta}-limit. The high-{beta} equilibria in SS and SMARTH ({beta}(0) > 30%, {beta}O 8-9%) are demonstrated, correspondingly, with the bootstrap current and the ohmic current. Possible experiments and scalings, including those for reactor parameters, are outlined. 38 refs., 6 figs., 1 tab.

157. Recent advances in the design of quasiaxisymmetric stellarator plasma configurations

Author

E. A. Lazarus, M. I. Mikhailov, M. Drevlak, Raul Sanchez, D. A. Monticello, Prashant M Valanju, George H. Neilson, Roscoe White, Charles Kessel, Guoyong Fu, Allen H. Boozer, W.H. Miner, P. Merkel, P. H. Rutherford, E.D. Fredrickson, S. R. Hudson, H. E. Mynick, B.E. Nelson, S.P. Hirshman, C. Nührenberg, L. P. Ku, W. Reiersen, Robert James Goldston, M. C. Zarnstorff, C. Jun, J. Schmidt, Dennis J Strickler, D. R. Mikkelsen, A. Brooks, Neil Pomphrey, M. Isaev, S. F. Knowlton, M. H. Redi, W. A. Cooper, A.A. Subbotin, J. L. V. Lewandowski, Allan Reiman, Lee A. Berry, R. Hatcher, J. F. Lyon, Zhihong Lin, and Donald A. Spong

Subjects
Surface (mathematics), Physics, Quality (physics), law, Flux, Plasma, Atomic physics, Condensed Matter Physics, Beneficial effects, Current density, Stellarator, Computational physics, law.invention
Abstract

Strategies for the improvement of quasiaxisymmetric stellarator configurations are explored. Calculations of equilibrium flux surfaces for candidate configurations are also presented. One optimization strategy is found to generate configurations with improved neoclassical confinement, simpler coils with lower current density, and improved flux surface quality relative to previous designs. The flux surface calculations find significant differences in the extent of islands and stochastic regions between candidate configurations. (These calculations do not incorporate the predicted beneficial effects of perturbed bootstrap currents.) A method is demonstrated for removing low order islands from candidate configurations by relatively small modifications of the configuration. One configuration is identified as having particularly desirable properties for a proposed experiment. (C) 2001 American Institute of Physics.

158. Overview of the RFX-mod contribution to the international Fusion Science Program

Author

M. Pavei, Alessandra Canton, Matteo Agostini, R. Piovan, Matteo Zuin, G. Mazzitelli, L. Piron, N. Vianello, J.Q. Dong, B. E. Chapman, A. Zamengo, Gianluca Spizzo, Paolo Zanca, T. Barbui, Hajime Sakakita, Piergiorgio Sonato, Nicola Pilan, Yueqiang Liu, Daniele Bonfiglio, P. Piovesan, Lorella Carraro, T.C. Luce, J. L. Jackson, C. Finotti, E. Miorin, M. Recchia, S.P. Hirshman, Rita Lorenzini, Andrea Rizzolo, Roberto Paccagnella, G. Ciaccio, A. Scaggion, Enrico Zilli, Nicolò Marconato, Paolo Scarin, S. Martini, M. Baruzzo, James D. Hanson, M. Veranda, L. Marrelli, M. Bigi, Marco Barbisan, W. A. Cooper, L. Zanotto, Piero Agostinetti, L. Laguardia, Chenguang Li, C. Taliercio, F. Fellin, Oliver Schmitz, Cristian Ruset, Luca Grando, Zhirui Wang, Lorenzo Frassinetti, Silvia Spagnolo, X. Y. Xu, Simone Peruzzo, B. Esposito, Erik Olofsson, Elena Gaio, M. Furno Palumbo, M. Okabayashi, Nisarg Patel, G. L. Trevisan, Matthias Komm, M. Spolaore, Francesco Gnesotto, S. C. Guo, Raul Sanchez, D. Terranova, Susanna Cappello, R. Bilel, G. Urso, Marco Gobbin, Fabio Villone, E. Spada, M. Moresco, D. Cester, Emanuele Sartori, L. Pigatto, Leonardo Giudicotti, B. Momo, Tommaso Bolzonella, Piero Martin, Luis Chacon, A. L. Roquemore, F. Belli, Barbara Zaniol, C. Piron, F. Sattin, N. Visona, F. Ghezzi, R. Delogu, Emilio Martines, Diego Marcuzzi, D. F. Escande, A. De Lorenzi, M. Dalla Palma, Paolo Franz, Cristina Rea, Adriano Luchetta, Paolo Bettini, Roscoe White, A. Maistrello, Alessandro Fassina, G. Rostagni, Manabu Takechi, Roberto Cavazzana, G. Viesti, M. Boldrin, V. Yanovskiy, Giuseppe Marchiori, D.K. Mansfield, Satoru Kiyama, W. A. Gonzales, M. Valisa, A. Buffa, Pavlos Xanthopoulos, J. S. Sarff, M. E. Puiatti, Go Matsunaga, M. Valente, S. M. Deambrosis, Alberto Ferro, Paolo Innocente, Italo Predebon, V. Rigato, S. Dal Bello, Gabriele Manduchi, Fulvio Auriemma, G. De Masi, P. Vincenzi, Donald A. Spong, M. Battistella, Songfen Liu, D. Marocco, M. Brombin, Laszlo Sajo-Bohus, Giuseppe Chitarin, A. Ruzzon, V. Antoni, L. Stevanato, Consorzio RFX, Associazione Euratom/ENEA sulla Fusione (RFX), Agenzia Nazionale per le nuove Tecnologie, l’energia e lo sviluppo economico sostenibile = Italian National Agency for New Technologies, Energy and Sustainable Economic Development (ENEA), Laboratori Nazionali di Frascati (LNF), Istituto Nazionale di Fisica Nucleare (INFN), National Institute for Laser, Plasma and Radiation Physics (INFLPR), STMicroelectronics [Crolles] (ST-CROLLES), Canadian Institute for Theoretical Astrophysics (CITA), Département Méthodes et Modèles Mathématiques pour l'Industrie (3MI-ENSMSE), École des Mines de Saint-Étienne (Mines Saint-Étienne MSE), Institut Mines-Télécom [Paris] (IMT)-Institut Mines-Télécom [Paris] (IMT)-Centre G2I, Physique des interactions ioniques et moléculaires (PIIM), Aix Marseille Université (AMU)-Centre National de la Recherche Scientifique (CNRS), Department of Physics [Stockholm], Stockholm University, Inst Subtrop Agr, Res Ctr Healthy Breeding Livestock & Poultry, Hunan Engn, Chinese Academy of Sciences [Changchun Branch] (CAS), Inst Subtrop Agr, Res Ctr Anim & Poultry Sci, Inst Subtrop Agr, Key Lab Agroecol Proc Subtrop Reg, Puiatti, M, Dal Bello, S, Marrelli, L, Martin, P, Agostinetti, P, Agostini, M, Antoni, V, Auriemma, F, Barbisan, M, Barbui, T, Baruzzo, M, Battistella, M, Belli, F, Bettini, P, Bigi, M, Bilel, R, Boldrin, M, Bolzonella, T, Bonfiglio, D, Brombin, M, Buffa, A, Canton, A, Cappello, S, Carraro, L, Cavazzana, R, Cester, D, Chacon, L, Chapman, B, Chitarin, G, Ciaccio, G, Cooper, W, Dalla Palma, M, Deambrosis, S, Delogu, R, De Lorenzi, A, De Masi, G, Dong, J, Escande, D, Esposito, B, Fassina, A, Fellin, F, Ferro, A, Finotti, C, Franz, P, Frassinetti, L, Palumbo, M, Gaio, E, Ghezzi, F, Giudicotti, L, Gnesotto, F, Gobbin, M, Gonzales, W, Grando, L, Guo, S, Hanson, J, Hirshman, S, Innocente, P, Jackson, J, Kiyama, S, Komm, M, Laguardia, L, Li, C, Liu, S, Liu, Y, Lorenzini, R, Luce, T, Luchetta, A, Maistrello, A, Manduchi, G, Mansfield, D, Marchiori, G, Marconato, N, Marocco, D, Marcuzzi, D, Martines, E, Martini, S, Matsunaga, G, Mazzitelli, G, Miorin, E, Momo, B, Moresco, M, Okabayashi, M, Olofsson, E, Paccagnella, R, Patel, N, Pavei, M, Peruzzo, S, Pilan, N, Pigatto, L, Piovan, R, Piovesan, P, Piron, C, Piron, L, Predebon, I, Rea, C, Recchia, M, Rigato, V, Rizzolo, A, Roquemore, A, Rostagni, G, Ruset, C, Ruzzon, A, Sajo-Bohus, L, Sakakita, H, Sanchez, R, Sarff, J, Sartori, E, Sattin, F, Scaggion, A, Scarin, P, Schmitz, O, Sonato, P, Spada, E, Spagnolo, S, Spolaore, M, Spong, D, Spizzo, G, Stevanato, L, Takechi, M, Taliercio, C, Terranova, D, Trevisan, G, Urso, G, Valente, M, Valisa, M, Veranda, M, Vianello, N, Viesti, G, Villone, F, Vincenzi, P, Visona', N, Wang, Z, White, R, Xanthopoulos, P, Xu, X, Yanovskiy, V, Zamengo, A, Zanca, P, Zaniol, B, Zanotto, L, Zilli, E, Zuin, M, and Italian National Agency for New Technologies, Energy and Sustainable Economic Development (ENEA)

Subjects
Convection, Physics, [PHYS]Physics [physics], Nuclear and High Energy Physics, Toroid, Tokamak, Reversed field pinch, Turbulence, single helicity, Electron, Mechanics, Sawtooth wave, reversed field pinch, Condensed Matter Physics, 01 natural sciences, 010305 fluids & plasmas, law.invention, 3D boundary, law, Physics::Plasma Physics, 0103 physical sciences, Magnetohydrodynamics, Atomic physics, 010306 general physics, tokamak
Abstract

25th Fusion Energy Conference (FEC), Govt Russian Federat, St ă Petersburg, RUSSIA, OCT 13-18, 2014; International audience; The RFX-mod device is operated both as a reversed field pinch (RFP), ă where advanced regimes featuring helical shape develop, and as a ă tokamak. Due to its flexibility, RFX-mod is contributing to the solution ă of key issues in the roadmap to ITER and DEMO, including MHD instability ă control, internal transport barriers, edge transport and turbulence, ă isotopic effect, high density limit and three-dimensional (3D) ă non-linear MHD modelling. This paper reports recent advancements in the ă understanding of the self-organized helical states, featuring a strong ă electron transport barrier, in the RFP configuration; the physical ă mechanism driving the residual transport at the barrier has been ă investigated. Following the first experiments with deuterium as the ă filling gas, new results concerning the isotope effect in the RFP are ă discussed. Studies on the high density limit show that in the RFP it is ă related to a toroidal particle accumulation due to the onset of a ă convective cell. In the tokamak configuration, q(a) regimes down to q(a) ă = 1.2 have been pioneered, with (2,1) tearing mode (TM) mitigated and ă (2,1) resistive wall mode (RWM) stabilized: the control of such modes ă can be obtained both by poloidal and radial sensors. Progress has been ă made in the avoidance of disruptions due to the (2,1) TM by applying ă q(a) control, and on the general issue of error field control. The ă effect of externally applied 3D fields on plasma flow and edge ă turbulence, sawtooth control and runaway electron decorrelation has been ă analysed. The experimental program is supported by substantial ă theoretical activity: 3D non-linear visco-resistive MHD and non-local ă transport modelling have been advanced; RWMs have been studied by a ă toroidal MHD kinetic hybrid stability code.

159. Physics issues in the design of high-beta, low-aspect-ratio stellarator experiments

Author

J. F. Lyon, C. Nuehrenberg, Allan Reiman, Raul Sanchez, Lee A. Berry, B.E. Nelson, M. H. Redi, W. Miner, P. Merkel, W. Reiersen, D. A. Monticello, M. Drevlak, Guoyong Fu, Allen H. Boozer, Prashant M Valanju, J. Schmidt, S.P. Hirshman, L. P. Ku, Robert James Goldston, Richard Majeski, W. A. Cooper, M. C. Zarnstorff, H. E. Mynick, Zhihong Lin, Neil Pomphrey, Donald A. Spong, George H. Neilson, and A. Brooks

Subjects
Physics, Tokamak, National Compact Stellarator Experiment, Plasma, Mechanics, Kink instability, Condensed Matter Physics, Bootstrap current, law.invention, Nuclear magnetic resonance, law, Physics::Plasma Physics, Beta (plasma physics), Plasma stability, Stellarator
Abstract

High-beta, low-aspect-ratio ("compact") stellarators are promising solutions to the problem of developing a magnetic plasma configuration for magnetic fusion power plants that can be sustained in steady state without disrupting. These concepts combine features of stellarators and advanced tokamaks and have aspect ratios similar to those of tokamaks (2-4). They are based on computed plasma configurations that are shaped in three dimensions to provide desired stability and transport properties. Experiments are planned as part of a program to develop this concept. A beta = 4% quasi-axisymmetric plasma configuration has been evaluated for the National Compact Stellarator Experiment (NCSX). It has a substantial bootstrap current and is shaped to stabilize ballooning, external kink, vertical, and neoclassical tearing modes without feedback or close-fitting conductors. Quasi-omnigeneous plasma configurations stable to ballooning modes at beta = 4% have been evaluated for the Quasi-Omnigeneous Stellarator (QOS) experiment. These equilibria have relatively low bootstrap currents and are insensitive to changes in beta. Coil configurations have been calculated that reconstruct these plasma configurations, preserving their important physics properties. Theory- and experiment-based confinement analyses are used to evaluate the technical capabilities needed to reach target plasma conditions. The physics basis for these complementary experiments is described. (C) 2000 American Institute of Physics. [S1070-664X(00)94905-X].

160. Observation of Alfvén eigenmodes driven by fast electrons during lower hybrid wave heating in EAST plasmas.

Author

Wenhui Hu, Jiangang Li, Bingjia Xiao, William W. Heidbrink, Tonghui Shi, Youjun Hu, Jiale Chen, Donald A. Spong, Haiqing Liu, Shouxin Wang, Shiyao Lin, Yongliang Li, Yi Yuan, Ruijie Zhou, and Team, The East

Subjects
PLASMA Alfven waves, PLASMA hybrid waves, SOLAR energetic particles, PLASMA oscillations, ELECTRON density
Abstract

Toroidal Alfvén eigenmodes (TAE) and ellipticity induced Alfvén eigenmodes (EAE) driven by fast electrons are observed for the first time in steady-state EAST plasmas heated by lower hybrid wave (LHW). For the analyzed discharge four modes appear after the injection of LHW. Comparing experimental observations with simulation, high frequency modes are located near and low frequency mode is near . The two positions are very close to where most of the heating power is deposited and population inversion occurs. Analysis of resonance condition between particles and waves indicates that barely-passing, deeply trapped and barely-trapped electrons can drive the mode. [ABSTRACT FROM AUTHOR]

Published
2018
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162. Hot plasma decoupling condition for long wavelength modes

Author

Donald A. Spong, J. W. Van Dam, and Herbert L Berk

Subjects
Core (optical fiber), Physics, Field line, Dispersion relation, Beta (plasma physics), General Engineering, Cylinder, Plasma, Decoupling (cosmology), Mechanics, Atomic physics, Instability
Abstract

The stability of layer modes is analyzed for z‐pinch and bumpy cylinder models. These modes have long wavelength across the layer and are flute‐like along the field line. The stability condition can be expressed in terms of the ratio of hot to core plasma density. It is shown that to achieve conditions close to the Lee–Van Dam, Nelson core beta limit, one needs a considerably smaller hot‐to‐core plasma density ratio than is required to achieve stability at zero core beta.

Published
1983

163. Observation of hot electron ring instabilities in ELMO Bumpy Torus

Author

R. J. Colchin, F. W. Baity, G. R. Haste, S. Hiroe, John B Wilgen, Lee A. Berry, Donald A. Spong, A. M. El Nadi, D. L. Hillis, Taner Uckan, W.A. Davis, and T.L. Owens

Subjects
Physics, Electron density, Neutron emission, Cyclotron, General Engineering, Torus, Plasma, Instability, law.invention, Ion, Physics::Plasma Physics, law, Neutron, Atomic physics
Abstract

A high‐frequency hot electron instability is observed in ELMO Bumpy Torus (EBT) plasmas when the hot electron‐to‐ion density ratio exceeds 0.4. Both the real frequency and the imaginary frequency are larger than the ion cyclotron frequency. The azimuthal mode number (m) is 7, and the instability rotates in the hot electron curvature drift direction. This instability is identified as a curvature‐driven mode. When it is strongly excited, the equilibrium of the hot electron annuli and confined plasmas are destroyed (disruption). Ion heating and neutron bursts are associated with this instability.

Published
1984

164. Curvature-driven instabilities in a hot electron plasma: Radial analysis

Author

Marshall N. Rosenbluth, Donald A. Spong, J. W. Van Dam, and Herbert L Berk

Subjects
Physics, Cyclotron, General Engineering, Torus, Mechanics, Plasma, Curvature, Instability, Ion, law.invention, Physics::Plasma Physics, law, Magnetohydrodynamic drive, Atomic physics, Marginal stability
Abstract

The theory of curvature‐driven instabilities is developed for a plasma interacting with a hot electron ring whose drift frequencies are larger than the growth rates predicted from conventional magnetohydrodynamic theory. A z‐pinch model is used to emphasize the radial structure of the problem. Stability criteria are obtained for the five possible modes of instability: the conventional hot electron interchange, a high‐frequency hot electron interchange (at frequencies larger than the ion cyclotron frequency), a compressional instability, a background pressure‐driven interchange, and an interacting pressure‐driven interchange. Numerical plots of the marginal stability boundaries are presented for parameter values corresponding to the EBT‐S and EBT‐P bumpy torus experiments.

Published
1983

165. Variational corrections to ELMO Bumpy Torus neoclassical ion plateau transport

Author

C. L. Hedrick and Donald A. Spong

Subjects
Physics, Distribution function, Variational method, Physics::Plasma Physics, Ambipolar diffusion, Variational principle, Quantum electrodynamics, General Engineering, Torus, Atomic physics, Collisionality, Scaling, Charged particle
Abstract

Low collisionality corrections to ELMO Bumpy Torus (EBT) ion plateau transport coefficients are calculated using a variational method. Using a bounce‐averaged drift kinetic equation and a drift orbit model appropriate to collisionless EBT ion transport, a solution is obtained that is accurate to first order in e(Ω0/ν0)2/3 (e is the inverse aspect ratio, ν0 is the 90° deflection frequency, and Ω0 is the average poloidal gradient B drift frequency). This is substituted into a variational principle (valid over both the plateau and banana regimes) from which particle and energy fluxes are obtained. The sensitivity of the transport rates with respect to variations in the radial and poloidal components of the ambipolar electric field and with respect to variations in the poloidal drift frequency scale length is examined. The transition from plateau to crescent orbit scaling occurs at approximately ν0/Ω0=e3/2.

Published
1980

166. Anisotropy effects on curvature-driven flute instabilities in a hot-electron plasma

Author

Marshall N. Rosenbluth, J. W. Van Dam, Donald A. Spong, and Herbert L Berk

Subjects
Physics, Condensed matter physics, General Engineering, Electron temperature, Plasma, Atomic physics, Curvature, Anisotropy, Instability, Hot electron, Magnetic field, Radius of curvature (optics)
Abstract

The effects of finite parallel temperature are investigated for a hot‐electron plasma with sufficiently large beta that the magnetic field scale length (ΔB) is small compared with the vacuum field radius of curvature (R). Numerical and analytical estimates of stability boundaries are obtained for the four possible modes that can be treated in this limit: the conventional hot‐electron interchange, the high‐frequency hot‐electron interchange (ω>ωci), the compressional Alfven mode, and the interacting pressure‐driven interchange.

Published
1983

167. Nonresonant electron transport in the ELMO Bumpy Torus experiment using a BGK operator

Author

Daniel E. Hastings and Donald A. Spong

Subjects
Physics, Field (physics), Ambipolar diffusion, Quantum electrodynamics, General Engineering, Torus, Plasma, Electron, Atomic physics, Diffusion (business), Bhatnagar–Gross–Krook operator, Mathematical Operators
Abstract

For the experimentally measured parameters in the ELMO Bumpy Torus (EBT) experiment, the electrons in the core plasma are nonresonant; that is, the average ∇B×B and E×B precessional drifts are in the same direction. Analytic transport rates exist for the electrons in the case where the ambipolar field is large relative to the plasma thermal energy. For finite fields, the diffusion coefficients have been calculated numerically. An analytic expansion away from the large field case that provides corrections to the results of Kovrizhnykh for finite fields has been developed from a BGK operator. These expressions are compared with the numerical calculations for parameters of experimental interest and it is shown that a substantially improved approximation over the Kovrizhnykh results can be obtained.

Published
1983

168. Radial structure of curvature-driven instabilities in a hot-electron plasma

Author

Herbert L Berk, J. W. Van Dam, and Donald A. Spong

Subjects
Physics, General Engineering, Plasma, Decoupling (cosmology), Curvature, Instability, Computational physics, Core (optical fiber), Wavelength, Physics::Plasma Physics, Physics::Space Physics, Wave resonance, Atomic physics, Hot electron
Abstract

A nonlocal analysis of curvature‐driven instabilities for a hot‐electron ring interacting with a warm background plasma has been made. Four different instability modes characteristic of hot‐electron plasmas have been examined: the high‐frequency hot‐electron interchange (at frequencies larger than the ion‐cyclotron frequency), the compressional Alfven instability, the interacting background pressure‐driven interchange, and the conventional hot‐electron interchange (at frequencies below the ion‐cyclotron frequency). The decoupling condition between core and hot‐electron plasmas has also been examined, and its influence on the background and hot‐electron interchange stability boundaries has been studied. The assumed equilibrium plasma profiles and resulting radial mode structure differ somewhat from those used in previous local analytic estimates; however, when the analysis is calibrated to the appropriate effective radial wavelength of the nonlocal calculation, reasonable agreement is obtained. Comparison with recent experimental measurements indicates that certain of these modes may play a role in establishing operating boundaries for the ELMO Bumpy Torus‐Scale (EBT‐S) experiment. The calculations given here indicate the necessity of having core plasma outside the ring to prevent the destabilizing wave resonance of the precessional mode with a cold plasma.

Published
1984

169. Major results from the first plasma campaign of the Wendelstein 7-X stellarator

Author

H. Maaßberg, M. Grahl, V. Moncada, Marek Scholz, Naoki Tamura, H. Neilson, R. Koziol, M. Krychowiak, A. Lücke, T. Estrada, R. Munk, M. Marushchenko, K. Toi, Heinrich P. Laqua, S. Paqay, Olaf Grulke, K. Baumann, A. Czermak, Ivan Calvo, Yasuhiro Suzuki, P.J. Heitzenroeder, H. Hölbe, G. Offermanns, Gintautas Dundulis, U. Stridde, H. Hunger, S. Valet, P. Denner, N. Krawczyk, O. Mishchenko, Andrey Samartsev, Mantas Povilaitis, Andrea Pavone, H. Schumacher, P. Aleynikov, H. P. Laqua, U. Wenzel, M. Sibilia, J. Ongena, Kian Rahbarnia, A. Galkowski, T.A. Scherer, C. Slaby, J. Nührenberg, H.-J. Roscher, Martin Köppen, L.-G. Böttger, A. Czarnecka, R. Krampitz, M. Zilker, T. Kremeyer, J. Wendorf, V. Bykov, A. Goriaev, Josef Preinhaelter, A. Alonso, Peter Titus, G. Czymek, Andreas Langenberg, Matteo Zuin, A. Gogoleva, F. Musielok, A. Zeitler, Andreas Schlaich, P. Xanthopoulos, Victoria Winters, M. Losert, D. A. Hartmann, Roberto Guglielmo Citarella, L. Pacios Rodriguez, Boyd Blackwell, E. Blanco, Hans-Stephan Bosch, R. König, R. Stadler, J. Mittelstaedt, Ch. Linsmeier, U. Höfel, N. Panadero Alvarez, E. Pasch, Francesco Cordella, M. Knaup, Fabian Wilde, M. C. Zarnstorff, B. Mendelevitch, Toru Ii Tsujimura, T. Szabolics, Hayato Tsuchiya, J.C. Schmitt, Tadas Kaliatka, Sadayoshi Murakami, Samuel Lazerson, W. Spiess, J. M. García Regaña, P. Junghans, María Sánchez, A. Grosman, I. Yamada, K. P. Hollfeld, K. Aleynikova, Gábor Náfrádi, T. Krings, Daniel Papenfuß, José Luis Velasco, P. Drewelow, N. A. Pablant, S. Renard, Alessandro Zocco, F. Wagner, D. Böckenhoff, S. Ryosuke, Michael Kramer, A. Vorkörper, M. Turnyanskiy, R. Riedl, W. Figacz, H. Trimino Mora, A. da Silva, D. Gradic, M. Keunecke, A. Pieper, M. Houry, S. Pingel, K. H. Schlüter, J. Loizu Cisquella, L. Carraro, S. Schmuck, M. Banduch, Sehyun Kwak, T. Ilkei, X. Huang, Stefan Illy, N. Fahrenkamp, I. Vakulchyk, G. Kocsis, Ph. Mertens, T. Morizaki, K. Czerski, F. V. Chernyshev, Bernd Heinemann, L. Lewerentz, B.J. Peterson, Francisco Castejón, Olaf Neubauer, D. Zhang, Torsten Bluhm, F. Köchl, C.P. von Thun, Michael Cole, Fabio Pisano, R. Brakel, Peter Traverso, G. Orozco, Wolf-Dieter Schneider, A. A. Ivanov, S. Sipliä, V. Szabó, D. Pilopp, A. Cappa, G. Anda, H. Braune, A. Krämer-Flecken, R. Sakamoto, A. Charl, Hiroshi Kasahara, Massimiliano Romé, J.-H. Feist, Mark Cianciosa, M. Führer, G. Schlisio, Taina Kurki-Suonio, F. Purps, H. Esteban, A. H. Reiman, J. Krom, C. D. Beidler, D. Loesser, H. M. Smith, Nengchao Wang, Axel Könies, Oliver Schmitz, T. Bräuer, M. Hirsch, Gabriel G. Plunk, Felix Warmer, R. Karalevicius, Riccardo Nocentini, J.L. Terry, John Jelonnek, Arnold Lumsdaine, L. Ryć, M. N. A. Beurskens, H. Jenzsch, Z. Sulek, Donald A. Spong, A. Khilchenko, P. Marek, R. Schroeder, T. Schröder, B. Standley, Manfred Thumm, B. Brünner, T. Fornal, Benedikt Geiger, H. Frerichs, R. Kleiber, T. Funaba, Andreas Meier, S. Degenkolbe, P. Rong, Dag Hathiramani, Matthias F. Schneider, Simppa Äkäslompolo, M. R. Stoneking, A. Dudek, Jiawu Zhu, X. Han, T. Windisch, Y. Wei, Detlev Reiter, J. Tretter, N. Rust, J. P. Kallmeyer, J. Baldzuhn, P. Bolgert, Dirk Timmermann, Shinsuke Satake, Luis Vela Vela, Yu. Turkin, Z. Szökefalvi-Nagy, Sigitas Rimkevicius, Naoki Kenmochi, Ulrich Neuner, M. Garcia-Munoz, V. Perseo, Matthias Otte, A. Puig Sitjes, Tamás Szepesi, A. da Molin, Alexis Terra, C. Guerard, J.M. Hernández Sánchez, A. Rodatos, J. Assmann, D. Höschen, Albert Mollén, A. Hölting, Tom Wauters, Adnan Ali, Ewa Pawelec, W. Kasparek, Ryo Yasuhara, D. Kinna, P. Sinha, B. Wiegel, Horacio Fernandes, M. E. Puiatti, S. Récsei, E. Ascasíbar, J.-M. Travere, C. Hidalgo, Joris Fellinger, H. Schmitz, Suguru Masuzaki, Katsumi Ida, G. Pelka, Jim-Felix Lobsien, S. Wolf, Jörg Schacht, J. Koshurinov, Han Zhang, P. Kornejew, J M Fontdecaba, T. Ngo, E. Wang, B. Hein, Gerd Gantenbein, Michael Drevlak, M. Vervier, J. W. Oosterbeek, H. Röhlinger, J. P. Knauer, B. Schweer, Jakub Urban, David Maurer, I. Ksiazek, David Gates, S. C. Liu, S. Massidda, F. Remppel, A.H. Wright, G. Satheeswaran, Monika Kubkowska, K. Rummel, Kai Jakob Brunner, Torsten Stange, J. Riemann, Thomas Klinger, S. Obermayer, H. Brand, Christine Hennig, A. Werner, N. Gierse, S. A. Henneberg, R. Vilbrandt, J. Wolowski, T. Sunn Pedersen, M. Dostal, G. A. Wurden, I. Abramovic, Carsten Lechte, R. Lang, S. A. Bozhenkov, G. Ehrke, K. J. McCarthy, Egidijus Urbonavicius, M. Schröder, S. Jablonski, Martina Huber, M. Nagel, Yunfeng Liang, O. P. Ford, Barbara Cannas, T. Mizuuchi, Anatoly Panin, Jan Skodzik, V. V. Lutsenko, R. Koslowski, R. Laube, Jonathan T. Green, B. Unterberg, Jeremy Lore, Laurie Stephey, J. H. E. Proll, M. Czerwinski, Venanzio Giannella, Jörg Weggen, S. Marsen, Clifford M Surko, Grzegorz Gawlik, B. Roth, D. Birus, Ch. Brandt, M. Mardenfeld, K. Riße, Y. Feng, Alexandra M. Freund, M. Vergote, S. Wadle, H. Thomsen, Wilfried Behr, A. Runov, L. Wegener, Burkhard Plaum, J. Svensson, Dmitry Moseev, Łukasz Ciupiński, G. M. Weir, E. Winkler, W. Pan, E. Erckmann, D. Mellein, B. Shanahan, Th. Kobarg, Marek Barlak, John Howard, Günter Dammertz, M. Endler, D.P. Dhard, N. Vianello, L. V. Lubyako, R. Burhenn, J. Thomas, N. Panadero, M. Gruca, T. Mönnich, J. Majano-Brown, Wolfgang Biel, S. Tulipán, J. H. Harris, C. Nührenberg, A. Carls, H. Viebke, Walter H. Fietz, L. Haiduk, S. Brezinsek, Heinz Grote, S. Langish, V. Huber, Jacek Jagielski, David Ennis, P. Kraszewsk, J. Kacmarczyk, Kunihiro Ogawa, U. Kamionka, O. Bertuch, F. Durodié, B. Missal, A. de la Peña, Robertas Alzbutas, Anett Spring, Yu Gao, Matt Landreman, Dirk Naujoks, Florian Effenberg, P. McNeely, Ya. I. Kolesnichenko, B. Gonçalves, B. van Millingen, M. Blatzheim, X. Peng, F. Harberts, M. W. Jakubowski, F. Köster, Gábor Cseh, Ph. Drews, Christoph Biedermann, G. Claps, L. Rudischhauser, Bernardo B. Carvalho, M. Yokoyama, Seung Gyou Baek, Felix Schauer, V. Borsuk, Th. Rummel, J. Boscary, Fumimichi Sano, J. R. Danielson, M. Rack, G. Fuchert, H.-J. Hartfuß, W. Leonhardt, Georg Kühner, D. R. Mikkelsen, M. Borchardt, A. Benndorf, P. Scholz, R. C. Wolf, I.V. Shikhovtsev, Holger Niemann, Andreas Zimbal, J. Geiger, T. Barbui, M. Lennartz, A. Lorenz, Andreas Dinklage, G. Krzesiński, J. Zajac, B. Israeli, R. Schrittwieser, M.J. Cole, S. Zoletnik, O. Marchuk, Per Helander, B. Buttenschön, P. van Eeten, Tamara Andreeva, Hiroshi Yamada, Universidad de Sevilla. Departamento de Física Atómica, Molecular y Nuclear, Max-Planck-Institut fur Plasmaphysik Teilinstitut Greifswald, Wendelsteinstr. 1, 17491 Greifswald, Germany, Centro de Investigaciones Energéticas, Medioambientales y Tecnológicas (CIEMAT), KFKI Research Institute for Particle and Nuclear Physics (KFKI-RMKI), Forschungszentrum Julich GmbH, Institut fur Energie- und Klimaforschung---Plasmaphysik, Partner of the Trilateral Euregio Cluster (TEC), Wilhelm-Johnen-Strase, 52428 Julich, Germany, University of Maryland, Princeton, Laboratory for Plasma Physics of the Ecole Royale Militaire/Koninklijke Militaire School (LPP-ERM/KMS), Avenue de la Renaissance 30, 1000 Bruxelles, Belgien, Los Alamos National Laboratory (LANL), Institute of Physics, Massachusetts Institute of Technology, Cambridge, University of Wisconsin-Madison, National Centre for Nuclear Research (NCBJ), Institut für Experimentelle Kernphysik, Universität Karlsruhe (IEKP), Geoscience Australia, Max Planck Institut für Plasma Physik and Excellence Cluster, Eindhoven University of Technology, Università degli Studi di Cagliari = University of Cagliari (UniCa), Consorzio Interuniversitario per la Fisica Spaziale (CIFS), Instituto Superior Técnico, Universidade de Lisboa (IST), A.F. Ioffe Physical-Technical Institute, Russian Academy of Sciences [Moscow] (RAS), Computer Science and Mathematics Division, Oak Ridge National Laboratory, Università di Milano, Warsaw University of Technology, ENEA-Frascati, IPPLM Institute of Plasma Physics and Laser Microfusion, 23 Hery Str., 01-497 Warsaw, Poland, Institute of Nuclear Physics PAN, University of Szczecin, 70-453, aleja Papieza Jana Pawla II 22A, Szczecin, Poland, Milano, University of California [San Diego] (UC San Diego), University of California (UC), International Center for Climate and Global Change Research and School of Forestry and Wildlife Sciences, Auburn University, Brandenburg University of Technology Cottbus-Senftenberg, Universitatsplatz 1, 01968 Senftenberg, Germany, National Institute for Fusion Science (NIFS), 322-6 Oroshicho, Toki, Gifu Prefecture 509-5202, Japan, Universidad Carlos III de Madrid (UC3M), Commissariat à l'énergie atomique et aux énergies alternatives (CEA), EURATOM/UKAEA Fusion Association, Culham Science Centre, Abingdon, Budker Institute of Nuclear Physics (BINP), 11, akademika Lavrentieva prospect, Novosibirsk, 630090, Russian Federation, Institut für Raumfahrtsysteme, Universität Stuttgart (IRS), Fraunhofer-Institut fur Schicht- und Oberflachentechnik IST, Bienroder Weg 54 E, 38108 Braunschweig, Germany, Institut für Weltraumforschung, Österreichische Akademie der Wissenschaften (IWF), Kiev Institute for Nuclear Research, A.M. Obukhov Institute of Atmospheric Physics, Russian Academy of Sciences (IAP), Institut für Optik und Atomare Physik, Technische Universität Berlin, University of Opole, plac Kopernika 11a, 45-001 Opole, Poland, School of Electrical Engineering, Aalto University, Physikalisch-Technische Bundesanstalt (PTB), Kyoto University, Institute of Plasma Physics, Chinese Academy of Sciences, 350 Shushanhu Rd., Hefei, Anhui 230031, People's Republic of China, Institute of Plasma Physics of the Czech Academy of Science, Za Slovankou 1782/3, 182 00 Prague 8---Liben, Czechia, Istituto di Fisica del Plasma, Consiglio Nazionale delle Ricerche (IFP-CNR), Fraunhofer-Institut fur Werkzeugmaschinen und Umformtechnik IWU, Reichenhainer Strase 88, 09126 Chemnitz, Germany, Universität Rostock, Wayne State University, Consiglio Nazionale delle Ricerche, Piazzale Aldo Moro, 7, 00185 Roma, Italy, Max Planck Institute for Plasma Physics, CIEMAT, Wigner Research Centre for Physics, Jülich Research Centre, University of Maryland, College Park, Princeton University, Royal Military Academy, Los Alamos National Laboratory, Lithuanian Energy Institute, Massachusetts Institute of Technology, Narodowe Centrum Badań Jadrowych, Karlsruhe Institute of Technology, Australian National University, University of Cagliari, National Research Council of Italy, Instituto Superior Tecnico Lisboa, Ioffe Institute, Oak Ridge National Laboratory, University of Salerno, Agenzia nazionale per le nuove tecnologie, l'energia e lo sviluppo economico sostenibile, Soltan Institute for Nuclear Studies, The Henryk Niewodniczanski Institute of Nuclear Physics of the Polish Academy of Sciences, University of Szczecin, University of Milan - Bicocca, University of California San Diego, Auburn University, Brandenburg University of Technology, National Institute for Fusion Science, Universidad Carlos III de Madrid, CEA, Culham Centre for Fusion Energy, RAS - Budker Institute of Nuclear Physics, University of Stuttgart, Fraunhofer Institute for Surface Engineering and Thin Films, Austrian Academy of Sciences, NASU - Institute of Nuclear Research, RAS - Institute of Applied Physics, Technical University of Berlin, University of Opole, Department of Applied Physics, Physikalisch-Technische Bundesanstalt, CAS - Institute of Plasma Physics, Czech Academy of Sciences, Istituto di Fisica Del Plasma Piero Caldirola, Fraunhofer Institute for Machine Tools and Forming Technology, University of Rostock, Lawrence University, Aalto-yliopisto, Aalto University, Science and Technology of Nuclear Fusion, Turbulence in Fusion Plasmas, Claps, G., and Cordella, F

Subjects
Magnetic confinement, Nuclear and High Energy Physics, Technology and Engineering, Plasma heating, Cyclotron resonance, CONFINEMENT, 01 natural sciences, Electron cyclotron resonance, 010305 fluids & plasmas, law.invention, PHYSICS, Nuclear physics, stellarator, current drive, magnetic confinement, plasma heating, Condensed Matter Physics, law, 0103 physical sciences, ddc:530, 010306 general physics, tellarator, Stellarator, Physics, Magnetic confinement fusion, Plasma, 530 Physik, TRANSPORT, Current drive, Electron temperature, Plasma diagnostics, Atomic physics, Wendelstein 7-X, [PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph]
Abstract

After completing the main construction phase of Wendelstein 7-X (W7-X) and successfully commissioning the device, first plasma operation started at the end of 2015. Integral commissioning of plasma start-up and operation using electron cyclotron resonance heating (ECRH) and an extensive set of plasma diagnostics have been completed, allowing initial physics studies during the first operational campaign. Both in helium and hydrogen, plasma breakdown was easily achieved. Gaining experience with plasma vessel conditioning, discharge lengths could be extended gradually. Eventually, discharges lasted up to 6 s, reaching an injected energy of 4 MJ, which is twice the limit originally agreed for the limiter configuration employed during the first operational campaign. At power levels of 4 MW central electron densities reached 3 × 1019 m−3 , central electron temperatures reached values of 7 keV and ion temperatures reached just above 2 keV. Important physics studies during this first operational phase include a first assessment of power balance and energy confinement, ECRH power deposition experiments, 2nd harmonic O-mode ECRH using multi-pass absorption, and current drive experiments using electron cyclotron current drive. As in many plasma discharges the electron temperature exceeds the ion temperature significantly, these plasmas are governed by core electron root confinement showing a strong positive electric field in the plasma centre. EURATOM 633053

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