Journal articles: 'Plasma edge theory'

1

Stangeby, P. C. "Plasma edge theory in fusion devices." Nuclear Fusion 32, no. 11 (November 1992): 2059–63. http://dx.doi.org/10.1088/0029-5515/32/11/424.

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2

Stacey, W. M. "Neoclassical theory of the plasma edge." Physics of Fluids B: Plasma Physics 5, no. 5 (May 1993): 1413–20. http://dx.doi.org/10.1063/1.860881.

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3

Stacey, W. M. "Recent Developments in Plasma Edge Theory." Contributions to Plasma Physics 56, no. 6-8 (July 12, 2016): 495–503. http://dx.doi.org/10.1002/ctpp.201610060.

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4

Hooper, E. B., R. H. Cohen, and D. D. Ryutov. "Theory of edge plasma in a spheromak." Journal of Nuclear Materials 278, no. 1 (February 2000): 104–10. http://dx.doi.org/10.1016/s0022-3115(99)00217-2.

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5

Carreras, Benjamin A. "Plasma edge cross-field transport: experiment and theory." Journal of Nuclear Materials 337-339 (March 2005): 315–21. http://dx.doi.org/10.1016/j.jnucmat.2004.10.034.

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6

Donnelly, I. J., B. E. Clancy, and N. F. Cramer. "Alfvén wave heating of a cylindrical plasma using axisymmetric waves. Part 2. Kinetic theory." Journal of Plasma Physics 35, no. 1 (February 1986): 75–106. http://dx.doi.org/10.1017/s0022377800011144.

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Kinetic theory, including ion Larmor radius effects, is used to analyse the Alfvén wave heating of cylindrical plasmas using axisymmetric waves excited by an antenna at frequencies up to the ion cyclotron frequency. At the Alfvén resonance position, the compressional wave is mode converted to a quasi-electrostatic wave (QEW) which propagates towards the plasma centre or edge depending on whether the plasma is hot or warm. The energy absorbed by the plasma agrees with the MHD theory predictions provided the QEW is heavily damped before reaching the plasma centre or edge; if it is not, then QEW resonances may occur with a consequent increase in antenna resistance. The relation between ion cyclotron wave resonances and QEW resonances in a hot plasma is shown. The behaviour described above is demonstrated by numerical solution of the wave equations for small and large tokamak-like plasmas. WKB theory has been used to derive useful expressions which quantify the QEW behaviour.

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Stacey, W. M. "Extended fluid transport theory in the tokamak plasma edge." Nuclear Fusion 57, no. 6 (May 3, 2017): 066034. http://dx.doi.org/10.1088/1741-4326/aa6b34.

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8

Rogister, A. L. "Revisited neoclassical transport theory for steep, collisional plasma edge profiles." Plasma Physics and Controlled Fusion 36, no. 7A (July 1, 1994): A213—A217. http://dx.doi.org/10.1088/0741-3335/36/7a/030.

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9

Rogister, André. "Revisited neoclassical transport theory for steep, collisional plasma edge profiles." Physics of Plasmas 1, no. 3 (March 1994): 619–35. http://dx.doi.org/10.1063/1.870807.

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10

Mondt, J. P., and J. Weiland. "Two-fluid theory of thermal transport in current-carrying edge plasma." Physica Scripta 39, no. 1 (January 1, 1989): 92–99. http://dx.doi.org/10.1088/0031-8949/39/1/014.

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11

Coster, D. P., R. Schneider, J. Neuhauser, B. Braams, and D. Reiter. "Theory and Modelling of Time Dependent Phenomena in the Plasma Edge." Contributions to Plasma Physics 36, no. 2-3 (1996): 150–60. http://dx.doi.org/10.1002/ctpp.2150360211.

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12

KRASHENINNIKOV, S. I., D. A. D'IPPOLITO, and J. R. MYRA. "Recent theoretical progress in understanding coherent structures in edge and SOL turbulence." Journal of Plasma Physics 74, no. 5 (October 2008): 679–717. http://dx.doi.org/10.1017/s0022377807006940.

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AbstractIn this paper we review some theoretical aspects of the dynamics of the mesoscale filaments extending along the magnetic field lines in the edge plasma, which are often called ‘blobs’. We start with a brief historical survey of experimental data and the main ideas on edge and SOL plasma transport, which finally evolved into the modern paradigm of convective very-intermittent cross-field edge plasma transport. We show that both extensive analytic treatments and numerical simulations demonstrate that plasma blobs with enhanced pressure can be convected coherently towards the wall. The mechanism of convection is related to an effective gravity force (e.g. owing to magnetic curvature effects), which causes plasma polarization and a corresponding E× B convection. The impacts of different effects (e.g. X-point magnetic geometry, plasma collisionality, plasma beta, etc.) on blob dynamics are considered. Theory and simulation predict, both for current tokamaks and for ITER, blob propagation speeds and cross-field sizes to be of the order of a few hundred meters per second and a centimeter, respectively, which are in reasonable agreement with available experimental data. Moreover, the concept of blobs as a fundamental entity of convective transport in the scrape-off layer provides explanations for observed outwards convective transport, intermittency and non-Gaussian statistics in edge plasmas, and enhanced wall recycling in both toroidal and linear machines.

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13

Mattor, Nathan, and Patrick H. Diamond. "Drift wave propagation as a source of plasma edge turbulence: Slab theory." Physics of Plasmas 1, no. 12 (December 1994): 4002–13. http://dx.doi.org/10.1063/1.870870.

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14

Mattor, Nathan. "Drift wave propagation as a source of plasma edge turbulence: Toroidal theory." Physics of Plasmas 2, no. 3 (March 1995): 766–76. http://dx.doi.org/10.1063/1.871429.

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15

LORTZ, D. "Stability of axisymmetric modes in plasma–vacuum equilibria." Journal of Plasma Physics 58, no. 4 (December 1997): 655–64. http://dx.doi.org/10.1017/s0022377897006181.

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A stability criterion for axisymmetric modes of ideal MHD equilibria without wall stabilization is derived for linear profiles with vanishing current density at the edge. Using perturbation theory, the critical half-axis ratio of the elliptical cross-section is computed for finite aspect ratio.

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16

Helander, P., and S. I. Krasheninnikov. "Transport theory in self-similar variables for neutrals atoms in an edge plasma." Contributions to Plasma Physics 36, no. 2-3 (1996): 344–48. http://dx.doi.org/10.1002/ctpp.2150360245.

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17

Stacey, W. M. "Necessary Extensions and Modification of Fluid Transport Theory for the Tokamak Plasma Edge." Fusion Science and Technology 74, no. 3 (February 22, 2018): 198–210. http://dx.doi.org/10.1080/15361055.2017.1416250.

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18

Stacey, Weston M. "A Particle-, Momentum-, and Energy-Conserving Fluid Transport Theory for the Tokamak Plasma Edge." Fusion Science and Technology 75, no. 4 (May 13, 2019): 251–63. http://dx.doi.org/10.1080/15361055.2019.1574529.

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19

Witalis, E. A. "Hall Effect, or Hyperbolic Magnetohydrodynamics, HMHD." Zeitschrift für Naturforschung A 42, no. 9 (September 1, 1987): 917–21. http://dx.doi.org/10.1515/zna-1987-0902.

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The MHD theory of present magnetic fusion research is briefly reviewed with emphasis on its mathematically diffusive character. The importance of retaining the Hall effect term, neglected in ideal or resistive MHD theory, is stressed. Elliptic MHD theory is critically dismissed. The Hall effect, or Hyperbolic, MagnetoHydro-Dynamics, HMHD, is shown to follow as the consequence of a revision of plasma electrodynamics so as to account for the fundamental plasma quasineutrality. The non-validity of Newton’s third law in charged particle contexts is then central. Previously poorly understood phenomena, such as plasma edge effects and magnetic field line reconnection are found to be inherent properties in this HMHD plasma description. The “magnetic bottle” principle for high density plasma confinement is shown to be physically unsound because there will exist a no-confinement plasma boundary region with HMHD theory properties. Arguments for non-thermal fusion, provided by HMHD theory, are given.

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20

Stacey, W. M. "Corrigendum: Extended fluid transport theory in the tokamak plasma edge (2017 Nucl. Fusion 57 066034)." Nuclear Fusion 57, no. 11 (August 9, 2017): 119501. http://dx.doi.org/10.1088/1741-4326/aa7e46.

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21

ONJUN, THAWATCHAI. "Pedestal temperature models based on first and second stability limits of ballooning modes." Laser and Particle Beams 24, no. 1 (March 2006): 113–16. http://dx.doi.org/10.1017/s0263034606060174.

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Models for the prediction of electron pedestal temperatures at the edge of type I ELMy H-mode plasmas are developed. These models are based on theory motivated concepts for pedestal width and pressure gradient. The pedestal pressure gradient is assumed to be limited by high n ballooning mode instabilities, where both the first and second stability limits are considered. The effect of the bootstrap current, which reduces the magnetic shear in the steep pressure gradient region at the edge of the H-mode plasma, can result in access to the second stability of ballooning mode. In these pedestal models, the magnetic shear and safety factor are calculated at one pedestal width away from separatrix. The predictions of these models are compared with the experimental electron pedestal temperatures for type I ELMy H-mode discharges obtained from the latest public version (version 3.2) in the International Tokamak Physics Activity Edge (ITPA) Pedestal Database.

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22

Benilov, M. S., and D. M. Thomas. "Asymptotic theory of double layer and shielding of electric field at the edge of illuminated plasma." Physics of Plasmas 21, no. 4 (April 2014): 043501. http://dx.doi.org/10.1063/1.4870013.

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23

Punjabi, Alkesh, and Min Soe†. "Bifurcations in an advanced two-chamber model for the edge plasma in a divertor tokamak." Journal of Plasma Physics 52, no. 3 (December 1994): 457–63. http://dx.doi.org/10.1017/s0022377800027252.

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An advanced two-chamber model for the main plasma scrape-off and the divertor chamber of a tokamak is constructed. It is studied in the framework of catastrophe theory. The model shows bifurcations in the topology of the equilibrium surfaces. The results are in qualitative agreement with some of the experimentally observed features of the H-mode transition.

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24

Ehlert, Christopher, Wolfgang E. S. Unger, and Peter Saalfrank. "C K-edge NEXAFS spectra of graphene with physical and chemical defects: a study based on density functional theory." Phys. Chem. Chem. Phys. 16, no. 27 (2014): 14083–95. http://dx.doi.org/10.1039/c4cp01106f.

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25

Rastovic, Danilo. "On L to H-mode transitions of the tokamak and entropy reduction." Nuclear Technology and Radiation Protection 21, no. 2 (2006): 14–20. http://dx.doi.org/10.2298/ntrp0602014r.

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In an ideal case, it is assumed that the models for tokamak and stellarator plasma behaviour lead to the theory of invariant manifolds by Rastovic [Chaos, Solitons & Fractals, 2007]. But, at the present state of knowledge a more realistic concept for describing L to H transitions and edge localized modes is the reduction of entropy and appropriate methods.

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26

Stacey, Weston M., and Brian A. Grierson. "Interpretation of rotation and momentum transport in the DIII-D edge plasma and comparison with neoclassical theory." Nuclear Fusion 54, no. 7 (May 8, 2014): 073021. http://dx.doi.org/10.1088/0029-5515/54/7/073021.

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27

KAMRAN, M., S. KUHN, D. D. TSKHAKAYA, and M. KHAN. "Extended Tonks–Langmuir-type model with non-Boltzmann-distributed electrons and cold ion sources." Journal of Plasma Physics 79, no. 2 (September 27, 2012): 169–87. http://dx.doi.org/10.1017/s0022377812000827.

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AbstractA general formalism for calculating the potential distribution Φ(z) in the quasineutral region of a new class of plane Tonks–Langmuir (TL)-type bounded-plasma-system (BPS) models differing from the well-known ‘classical’ TL model (Tonks, L. and Langmuir, I. 1929 A general theory of the plasma of an arc. Phys. Rev. 34, 876) by allowing for arbitrary (but still cold) ion sources and arbitrary electron distributions is developed. With individual particles usually undergoing microscopic collision/sink/source (CSS) events, extensive use is made here of the basic kinetic-theory concept of ‘CSS-free trajectories’ (i.e., the characteristics of the kinetic equation). Two types of electron populations, occupying the ‘type-t’ and ‘type-p’ domains of electron phase space, are distinguished. By definition, the type-t and type-p domains are made up of phase points lying on type-t (‘trapped’) CSS-free trajectories (not intersecting the walls and closing on themselves) and type-p (‘passing’) ones (starting at one of the walls and ending at the other). This work being the first step, it is assumed that ε ≡ λD/l → 0+ (where λD and l are a typical Debye length and a typical ionization length respectively) so that the system exhibits a finite quasineutral ‘plasma’ region and two infinitesimally thin ‘sheath’ regions associated with the ‘sheath-edge singularities’ | dΦ/dz|z→±zs → ∞. The potential in the plasma region is required to satisfy a plasma equation (quasineutrality condition) of the form ni {Φ} =ne (Φ), where the electron density ne (Φ) is given and the ion density ni {Φ} is expressed in terms of trajectory integrals of the ion kinetic equation, with the ions produced by electron-impact ionization of cold neutrals. While previous TL-type models were characterized by electrons diffusing under the influence of frequent collisions with the neutral background particles and approximated by Maxwellian (Riemann, K.-U. 2006 Plasma-sheath transition in the kinetic Tonks–Langmuir model. Phys. Plasmas 13, 063508) or bi-Maxwellian (Godyak, V. A. et al. 1995 Tonks–Langmuir problem for a bi-Maxwellian plasma. IEEE Trans. Plasma Sci. 23, 728) electron velocity distribution functions (VDFs), which satisfy the zero-CSS-term (Vlasov) kinetic equation and imply zero electron currents, we here propose a more general class of electron VDFs allowing, in an approximate manner, for non-zero CSS terms and finite electron currents inside the plasma region. The sheath-edge and floating-wall potentials are calculated by balancing the ion and electron current densities at sheath-edge singularities. In a first detailed application, the type-t and type-p electron VDFs are assumed to be ‘inner’ and ‘outer’ cut-off Maxwellians respectively, with different amplitudes and ‘formal’ temperatures, implying the perfectly CSS-free limit. For the special case of equal type-t and type-p electron VDF amplitudes and formal temperatures, the classical Boltzmann distribution for electrons is formally retrieved. Special cases with other amplitude and formal-temperature ratios show significant deviations from the classical case.

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28

Chow, Weng W., and Hans Christian Schneider. "The Application of Gain Theory to Vertical-Cavity Surface-Emitting Lasers." MRS Bulletin 27, no. 7 (July 2002): 525–30. http://dx.doi.org/10.1557/mrs2002.171.

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AbstractThe development of vertical-cavity surface-emitting lasers (VCSELs) relies on an understanding of gain-medium physics, more so than in edge-emitting lasers. An important tool in the investigation of semiconductor gain behavior is a theory that provides a systematic account of the interaction between the laser field and the electron–hole plasma, the influence of the band structure, and the many-body effects due to Coulomb interactions among carriers. This article describes a semiclassical approach that is based on the semiconductor Bloch equations, with carrier correlation effects described at the level of quantum kinetic theory. To illustrate its application, we discuss research activities involving the development of gain media for long-wavelength VCSELs.

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29

DU, DAN, XUEYU GONG, ZHENHUA WANG, JUN YU, and PINGWEI ZHENG. "Theoretical analysis of the ICRH antenna's impedance matching for ELMy plasmas on EAST." Journal of Plasma Physics 78, no. 6 (April 19, 2012): 595–99. http://dx.doi.org/10.1017/s0022377812000396.

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AbstractA well-optimized design of an ion cyclotron resonance heating (ICRH) antenna is very important for steady-state plasma heating with high radio frequency (RF) power of several tens of megawatts. However, a sharp decrease in the coupling RF power because of impedance mismatch of ICRH system is an issue that must be resolved for present-day fusion reactors and International Thermonuclear Experimental Reactor. This paper has theoretically analyzed the ICRH antenna's impedance matching for ELMy plasmas on experimental advanced superconducting tokamak (EAST) by the transmission line theory. The results indicate that judicious choice of the optimal feeder location is found useful for adjustable capacitors' tolerance to the variations of the antenna input impedance during edge-localized mode (ELM) discharge, which is expected to be good for the design of ICRH antenna system and for real-time feedback control during ELM discharge on EAST.

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30

Krasheninnikov, Sergei. "17th International Workshop on Plasma Edge Theory in Fusion Devices, August 19-21, 2019, University California San Diego, La Jolla, USA." Contributions to Plasma Physics 60, no. 5-6 (June 2020): e202090016. http://dx.doi.org/10.1002/ctpp.202090016.

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31

Berczeli, Miklós, and Zoltán Weltsch. "Enhanced Wetting and Adhesive Properties by Atmospheric Pressure Plasma Surface Treatment Methods and Investigation Processes on the Influencing Parameters on HIPS Polymer." Polymers 13, no. 6 (March 15, 2021): 901. http://dx.doi.org/10.3390/polym13060901.

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The development of bonding technology and coating technologies require the use of modern materials and topologies for the demanding effect and modification of their wetting properties. For the industry, a process modification process that can be integrated into a process is the atmospheric pressure of air operation plasma surface treatment. This can be classified and evaluated based on the wettability, which has a significant impact on the adhesive force. The aim is to improve the wetting properties and to find the relationship between plasma treatment parameters, wetting, and adhesion. High Impact PolyStyrene (HIPS) was used as an experimental material, and then the plasma treatment can be treated with various adjustable parameters. The effect of plasma parameters on surface roughness, wetting contact angle, and using Fowkes theory of the surface energy have been investigated. Seven different plasma jet treatment distances were tested, combined with 5 scan speeds. Samples with the best plasma parameters were prepared from 25 mm × 25 mm overlapping adhesive joints using acrylic/cyanoacrylate. The possibility of creating a completely hydrophilic surface was achieved, where the untreated wetting edge angle decreased from 88.2° to 0° for distilled water and from 62.7° to 0° in the case of ethylene glycol. The bonding strength of High Impact PolyStyrene was increased by plasma treatment by 297%.

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32

Li, Jing, Tingting Quan, Wei Zhang, and Wei Deng. "The Dynamic Mutation Characteristics of Thermonuclear Reaction in Tokamak." Scientific World Journal 2014 (2014): 1–10. http://dx.doi.org/10.1155/2014/841891.

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The stability and bifurcations of multiple limit cycles for the physical model of thermonuclear reaction in Tokamak are investigated in this paper. The one-dimensional Ginzburg-Landau type perturbed diffusion equations for the density of the plasma and the radial electric field near the plasma edge in Tokamak are established. First, the equations are transformed to the average equations with the method of multiple scales and the average equations turn to be aZ2-symmetric perturbed polynomial Hamiltonian system of degree 5. Then, with the bifurcations theory and method of detection function, the qualitative behavior of the unperturbed system and the number of the limit cycles of the perturbed system for certain groups of parameter are analyzed. At last, the stability of the limit cycles is studied and the physical meaning of Tokamak equations under these parameter groups is given.

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33

Raghunathan, M., Y. Marandet, H. Bufferand, G. Ciraolo, Ph Ghendrih, P. Tamain, and E. Serre. "Generalized collisional fluid theory for multi-component, multi-temperature plasma using the linearized Boltzmann collision operator for scrape-off layer/edge applications." Plasma Physics and Controlled Fusion 63, no. 6 (May 4, 2021): 064005. http://dx.doi.org/10.1088/1361-6587/abf670.

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34

Bimonte, Giuseppe, Benjamin Spreng, Paulo A. Maia Neto, Gert-Ludwig Ingold, Galina L. Klimchitskaya, Vladimir M. Mostepanenko, and Ricardo S. Decca. "Measurement of the Casimir Force between 0.2 and 8 μm: Experimental Procedures and Comparison with Theory." Universe 7, no. 4 (April 7, 2021): 93. http://dx.doi.org/10.3390/universe7040093.

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We present results on the determination of the differential Casimir force between an Au-coated sapphire sphere and the top and bottom of Au-coated deep silicon trenches performed by means of the micromechanical torsional oscillator in the range of separations from 0.2 to 8 μm. The random and systematic errors in the measured force signal are determined at the 95% confidence level and combined into the total experimental error. The role of surface roughness and edge effects is investigated and shown to be negligibly small. The distribution of patch potentials is characterized by Kelvin probe microscopy, yielding an estimate of the typical size of patches, the respective r.m.s. voltage and their impact on the measured force. A comparison between the experimental results and theory is performed with no fitting parameters. For this purpose, the Casimir force in the sphere-plate geometry is computed independently on the basis of first principles of quantum electrodynamics using the scattering theory and the gradient expansion. In doing so, the frequency-dependent dielectric permittivity of Au is found from the optical data extrapolated to zero frequency by means of the plasma and Drude models. It is shown that the measurement results exclude the Drude model extrapolation over the region of separations from 0.2 to 4.8 μm, whereas the alternative extrapolation by means of the plasma model is experimentally consistent over the entire measurement range. A discussion of the obtained results is provided.

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35

Prakash, R., R. P. Singh, R. C. Awasthi, and D. P. Singh. "A theoretical verification of intensity of plasmaspheric ELF hiss emissions: theory versus GEOS-1 observations." Annales Geophysicae 15, no. 6 (June 30, 1997): 597–602. http://dx.doi.org/10.1007/s00585-997-0597-x.

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Abstract. An attempt is made to confirm the generation mechanism of plasmaspheric ELF hiss emissions observed aboard GEOS-1 satellite in the equatorial region both at small and large wave normal angles by calculating their magnetic field intensities in terms of incoherent Cerenkov radiation mechanism and cyclotron resonance instability mechanism, using appropriate and suitable plasma parameters. The ELF intensities calculated by Cerenkov radiation mechanism, being 4 to 5 orders of magnitude lower than the observed intensities, rule out the possibility of their generation by this mechanism. On the other hand, the intensities calculated under electron cyclotron resonance instability mechanism are found to be large enough to account for both the observed intensity and propagation losses and hence to confirm that plasmaspheric ELF hiss emissions observed aboard GEOS-1 satellite both at small and large wave normal angles were originally generated in the equatorial region by this mechanism just near the inner edge of the plasmapause. The difference in the observed intensities of two types of the emissions has been attributed to the propagation effect rather than the generation effect.

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36

Voigt, Gerd-Hannes. "Quasi-static MHD processes in Earth's magnetosphere." Laser and Particle Beams 6, no. 3 (August 1988): 525–37. http://dx.doi.org/10.1017/s0263034600005449.

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The purpose of this paper is to demonstrate how the MHD equilibrium theory can be used to describe the global magnetic field configuration of Earth's magnetosphere and its time evolution under the influence of magnetospheric convection. The MHD equilibrium theory represents magneto-hydrodynamics in the slow-flow approximation. In this approximation time scales are long compared to typical Alfvén wave travel times, and plasma flow velocities are small compared to the Alfvén speed. Under those conditions, the inertial term ρ(dv/dt) in the MHD equation of motion is a small second order term which can be neglected. The MHD equilibrium theory is not a static theory, though, because time derivatives and flow velocities remain first order quantities in the continuity equation, in the thermodynamic equation of state, and in the induction equation. Therefore one can compute slowly time-dependent processes, such as magnetospheric convection, in terms of series of static equilibrium states. However, those series are not arbitrary; they are constrained by thermodynamic conditions according to which the magnetosphere evolves in time.It is an interesting question, whether or not the magnetosphere, driven by slow, lossless, adiabatic, earthward convection of magnetotail flux tubes, can reach a steady state. There exist magnetospheric equilibria in which magnetotail flux tubes satisfy the steady-state condition d/dt (Pρ−γ) = 0. Those configurations exhibit a deep magnetic field minimum in the equatorial plane, near the inner edge of the tail plasma sheet. The magnetosphere becomes tearing-mode unstable in the neighborhood of such a minimum, thus leading to periodic onsets of substorms in the inner plasma sheet. This explains why distinct magnetic field minima have not been observed in this region. Magnetic substorms seem to be an inevitable element of the global convection cycle which inhibit the establishment of an ultimate steady state.MHD equilibria discussed in this paper result from linear and non-linear solutions to the two-dimensional Grad-Shafranov equation for isotropic thermal plasma pressure.

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37

Serpieri, Jacopo, Srikar Yadala Venkata, and Marios Kotsonis. "Conditioning of cross-flow instability modes using dielectric barrier discharge plasma actuators." Journal of Fluid Mechanics 833 (November 2, 2017): 164–205. http://dx.doi.org/10.1017/jfm.2017.707.

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In the current study, selective forcing of cross-flow instability modes evolving on a $45^{\circ }$ swept wing at $Re=2.17\times 10^{6}$ is achieved by means of spanwise-modulated plasma actuators, positioned near the leading edge. In the perspective of laminar flow control, the followed methodology holds on the discrete roughness elements/upstream flow deformation (DRE/UFD) approach, thoroughly investigated by e.g. Saric et al. (AIAA Paper 1998-781, 1998), Malik et al. (J. Fluid Mech., vol. 399, 1999, pp. 85–115) and Wassermann & Kloker (J. Fluid Mech., vol. 456, 2002, pp. 49–84). The possibility of using active devices for UFD provides several advantages over passive means, allowing for a wider range of operating $Re$ numbers and pressure distributions. In the present work, customised alternating current dielectric barrier discharge plasma actuators have been designed, manufactured and characterised. The authority of the actuators in forcing monochromatic stationary cross-flow modes at different spanwise wavelengths is assessed by means of infrared thermography. Moreover, quantitative spatio-temporal measurements of the boundary layer velocity field are performed using time-resolved particle image velocimetry. The results reveal distinct steady and unsteady forcing contributions of the plasma actuator on the boundary layer. It is shown that the actuators introduce unsteady fluctuations in the boundary layer, amplifying at frequencies significantly lower than the actuation frequency. In line with the DRE/UFD strategy, forcing a sub-critical stationary mode, with a shorter wavelength compared to the naturally selected mode, results in less amplified primary vortices and related fluctuations, compared to the critical forcing case. The effect of the forcing on the flow stability is further inspected by combining the measured actuators body force with the numerical solution of the laminar boundary layer and linear stability theory. The simplified methodology yields fast and computationally cheap estimates on the effect of steady forcing (magnitude and direction) on the boundary layer stability.

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38

Qin, H., R. H. Cohen, W. M. Nevins, and X. Q. Xu. "Geometric gyrokinetic theory for edge plasmas." Physics of Plasmas 14, no. 5 (May 2007): 056110. http://dx.doi.org/10.1063/1.2472596.

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39

Biermann, Peter L., Philipp P. Kronberg, Michael L. Allen, Athina Meli, and Eun-Suk Seo. "The Origin of the Most Energetic Galactic Cosmic Rays: Supernova Explosions into Massive Star Plasma Winds." Galaxies 7, no. 2 (April 14, 2019): 48. http://dx.doi.org/10.3390/galaxies7020048.

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We propose that the high energy Cosmic Ray particles up to the upturn commonly called the ankle, from around the spectral turn-down commonly called the knee, mostly come from Blue Supergiant star explosions. At the upturn, i.e., the ankle, Cosmic Rays probably switch to another source class, most likely extragalactic sources. To show this we recently compiled a set of Radio Supernova data where we compute the magnetic field, shock speed and shock radius. This list included both Blue and Red Supergiant star explosions; both data show the same magnetic field strength for these two classes of stars despite very different wind densities and velocities. Using particle acceleration theory at shocks, those numbers can be transformed into characteristic ankle and knee energies. Without adjusting any free parameters both of these observed energies are directly indicated by the supernova data. In the next step in the argument, we use the Supernova Remnant data of the starburst galaxy M82. We apply this analysis to Blue Supergiant star explosions: The shock will race to their outer edge with a magnetic field that is observed to follow over several orders of magnitude B ( r ) × r ∼ c o n s t . , with in fact the same magnetic field strength for such stellar explosions in our Galaxy, and other galaxies including M82. The speed is observed to be ∼0.1 c out to about 10 16 cm radius in the plasma wind. The Supernova shock can run through the entire magnetic plasma wind region at full speed all the way out to the wind-shell, which is of order parsec scale in M82. We compare and identify the Cosmic Ray spectrum in other galaxies, in the starburst galaxy M82 and in our Galaxy with each other; we suggest how Blue Supergiant star explosions can provide the Cosmic Ray particles across the knee and up to the ankle energy range. The data from the ISS-CREAM (Cosmic Ray Energetics and Mass Experiment at the International Space Station) mission will test this cosmic ray concept which is reasonably well grounded in two independent radio supernova data sets. The next step in developing our understanding will be to obtain future more accurate Cosmic Ray data near to the knee, and to use unstable isotopes of Cosmic Ray nuclei at high energy to probe the “piston” driving the explosion. We plan to incorporate these data with the physics of the budding black hole which is probably forming in each of these stars.

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Tsytovich, V. N., S. Benkadda, and S. V. Vladimirov. "Theory of self-organized dust sheaths in edge plasmas." Czechoslovak Journal of Physics 48, S2 (February 1998): 71–80. http://dx.doi.org/10.1007/s10582-998-0024-x.

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Mondt, J. P., and J. Liu. "Theory of thermal solitary vortices in current-carrying edge plasmas." Journal of Plasma Physics 36, no. 2 (October 1986): 235–42. http://dx.doi.org/10.1017/s0022377800011715.

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It is shown that the nonlinear dynamics of current-convective excitations in current-carrying edge plasmas allows for the existence of solitary vortices despite the effects of magnetic shear and dissipation in the form of parallel electron thermal conductivity. The potential importance of this finding with regard to heat balance is pointed out.

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WEILAND, JAN. "Nonlinear condensation modes." Journal of Plasma Physics 76, no. 3-4 (January 26, 2010): 487–92. http://dx.doi.org/10.1017/s0022377809990778.

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AbstractIn the far edge, in L-mode plasmas and the outer parts of the H-mode barrier, tokamak plasmas may be so collisional that parallel electron motion can be neglected or included as a perturbation. Thus we have a regime that is basically two dimensional. We will here consider the outer part of the H-mode barrier where transport is small. Recently a condensation mode was found for this regime. We have extended the theory to the nonlinear regime.

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Marsch, E., and S. Bourouaine. "Velocity-space diffusion of solar wind protons in oblique waves and weak turbulence." Annales Geophysicae 29, no. 11 (November 24, 2011): 2089–99. http://dx.doi.org/10.5194/angeo-29-2089-2011.

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Abstract. The fast solar wind is permeated by all kinds of plasma waves which have a broad range of wavelengths and occur on many different scales. Kinetically, a plasma wave induces ion-wave interactions which can within the quasi-linear theory be described as a diffusion process. The impact this diffusion may have on the shape of the proton velocity distribution function (VDF) is studied. We first analyse theoretically some of the possible kinetic effects of the waves on the ions. Then the model predictions are compared with the detailed in-situ plasma measurements made by the Helios spacecraft on 14 April 1976 at 0.3 AU and found to comply favourably with resonant diffusion of protons in obliquely propagating magnetohydrodynamic waves. In particular, the shape at the edges of the VDFs at positive proton velocities in the wind frame can be well explained by cyclotron-resonant diffusion of the protons in oblique fast magnetoacoustic and Alfvén waves propagating away from the Sun.

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Punjabi, Alkesh, and George Vahala. "Effects of positive potential in the catastrophe theory study of the point model for bumpy tori." Journal of Plasma Physics 33, no. 1 (February 1985): 119–49. http://dx.doi.org/10.1017/s0022377800002361.

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With positive ambipolar potential, ion non-resonant neoclassical transport leads to increased particle confinement times. In certain regimes of filling pressure, microwave powers (ECRH and ICRH) and positive potential, new folds can now emerge from previously degenerate equilibrium surfaces allowing for distinct C, T, and M modes of operation. A comparison in the equilibrium fold structure is also made between (i) equal particle and energy confinement times, and (ii) particle confinement times enhanced over the energy confinement time. The nonlinear time evolution of these point model equations is considered and confirms the delay convention occurrences at the fold edges. It is clearly seen that the time-asymptotic equilibrium state is very sensitive, not only to the values of the control parameters (neutral density, ambipolar electrostatic potential, electron and ion cyclotron power densities) but also to the initial conditions on the plasma density, and electron and ion temperatures.

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"5th International Workshop on Plasma Edge Theory in Fusion Devices Proceeding." Contributions to Plasma Physics 36, no. 2-3 (1996): 95–96. http://dx.doi.org/10.1002/ctpp.2150360202.

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"16th International Workshop “Plasma Edge Theory in Fusion Devices” Marseille, France (September 27-29, 2017)." Contributions to Plasma Physics 58, no. 6-8 (July 2018): 430–33. http://dx.doi.org/10.1002/ctpp.201790040.

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Turnbull, A. D., J. M. Hanson, F. Turco, N. M. Ferraro, M. J. Lanctot, L. L. Lao, E. J. Strait, P. Piovesan, and P. Martin. "The external kink mode in diverted tokamaks." Journal of Plasma Physics 82, no. 3 (June 2016). http://dx.doi.org/10.1017/s0022377816000568.

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An explanation is provided for the disruptive instability in diverted tokamaks when the safety factor$q$at the 95 % poloidal flux surface,$q_{95}$, is driven below 2.0. The instability is a resistive kink counterpart to the current-driven ideal mode that traditionally explained the corresponding disruption in limited cross-sections (Shafranov,Sov. Phys. Tech. Phys., vol. 15, 1970, p. 175) when$q_{edge}$, the safety factor at the outermost closed flux surface, lies just below a rational value$m/n$. Experimentally, external kink modes are observed in limiter configurations as the current in a tokamak is ramped up and$q_{edge}$decreases through successive rational surfaces. For$q_{edge}<2$, the instability is always encountered and is highly disruptive. However, diverted plasmas, in which$q_{edge}$is formally infinite in the magnetohydrodynamic (MHD) model, have presented a longstanding difficulty since the theory would predict stability, yet, the disruptive limit occurs in practice when$q_{95}$, reaches 2. It is shown from numerical calculations that a resistive kink mode is linearly destabilized by the rapidly increasing resistivity at the plasma edge when$q_{95}<2$, but$q_{edge}\gg 2$. The resistive kink behaves much like the ideal kink with predominantly kink or interchange parity and no real sign of a tearing component. However, the growth rates scale with a fractional power of the resistivity near the$q=2$surface. The results have a direct bearing on the conventional edge cutoff procedures used in most ideal MHD codes, as well as implications for ITER and for future reactor options.

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Pétri, Jérôme. "Theory of pulsar magnetosphere and wind." Journal of Plasma Physics 82, no. 5 (September 19, 2016). http://dx.doi.org/10.1017/s0022377816000763.

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Neutron stars are fascinating astrophysical objects immersed in strong gravitational and electromagnetic fields, at the edge of our current theories. These stars manifest themselves mostly as pulsars, emitting a timely very stable and regular electromagnetic signal. Even though discovered almost fifty years ago, they still remain mysterious compact stellar objects. In this review, we summarize the most fundamental theoretical aspects of neutron star magnetospheres and winds. The main competing models explaining their radiative properties like multi-wavelength pulse shapes and spectra and the underlying physical processes such as pair creation and radiation mechanisms are scrutinized. A global but still rather qualitative picture slowly emerges thanks to recent advances in numerical simulations on the largest scales. However considerations about pulsar magnetospheres remain speculative. For instance, the exact composition of the magnetospheric plasma is not yet known. Is it solely filled with a mixture of$e^{\pm }$ leptons or does it contain a non-negligible fraction of protons and/or ions? Is it almost entirely filled or mostly empty except for some small anecdotal plasma filled regions? Answers to these questions will strongly direct the description of the magnetosphere to seemingly contradictory results leading sometimes to inconsistencies. Nevertheless, accounts are given as to the latest developments in the theory of pulsar magnetospheres and winds, the existence of a possible electrosphere and physical insight obtained from related observational signatures of multi-wavelength pulsed emission.

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Kobayashi, T., H. Takahashi, K. Nagaoka, M. Sasaki, M. Nakata, M. Yokoyama, R. Seki, M. Yoshinuma, and K. Ida. "Isotope effects in self-organization of internal transport barrier and concomitant edge confinement degradation in steady-state LHD plasmas." Scientific Reports 9, no. 1 (November 4, 2019). http://dx.doi.org/10.1038/s41598-019-52271-w.

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Abstract The isotope effect, which has been a long-standing mystery in the turbulent magnetically confined plasmas, is the phenomena that the plasma generated with heavier hydrogen isotope show a mitigated transport. This is on the contrary to what is predicted with the simple scaling theory, in which the heavier ions easily diffuse because of its larger gyro-radius. Thanks to the newly developed analysis method and a comprehensive parameter scan experiment in the steady-state plasmas in the Large Helical Device (LHD), the isotope effect was clearly observed in the self-organized internal transport barrier (ITB) structure for the first time. Comparing the ITB intensity in deuterium (D) and hydrogen (H) plasmas, two distinct hydrogen isotope effects are found: stronger ITB is formed in D plasmas and a significant edge confinement degradation accompanied by the ITB formation emerges in H plasmas. This observation sheds light on a new aspect of the turbulent plasmas regarding how the basic properties of the fluid material affect the turbulent structure formation in the open-system.

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Myra, J. R., D. A. D’Ippolito, D. A. Russell, M. V. Umansky, and D. A. Baver. "Analytical and numerical study of the transverse Kelvin–Helmholtz instability in tokamak edge plasmas." Journal of Plasma Physics 82, no. 2 (April 2016). http://dx.doi.org/10.1017/s0022377816000301.

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Sheared flows perpendicular to the magnetic field can be driven by the Reynolds stress or ion pressure gradient effects and can potentially influence the stability and turbulent saturation level of edge plasma modes. On the other hand, such flows are subject to the transverse Kelvin–Helmholtz (KH) instability. Here, the linear theory of KH instabilities is first addressed with an analytic model in the asymptotic limit of long wavelengths compared with the flow scale length. The analytic model treats sheared $\boldsymbol{E}\times \boldsymbol{B}$ flows, ion diamagnetism (including gyro-viscous terms), density gradients and parallel currents in a slab geometry, enabling a unified summary that encompasses and extends previous results. In particular, while ion diamagnetism, density gradients and parallel currents each individually reduce KH growth rates, the combined effect of density and ion pressure gradients is more complicated and partially counteracting. Secondly, the important role of realistic toroidal geometry is explored numerically using an invariant scaling analysis together with the 2DX eigenvalue code to examine KH modes in both closed and open field line regions. For a typical spherical torus magnetic geometry, it is found that KH modes are more unstable at, and just outside of, the separatrix as a result of the distribution of magnetic shear. Finally implications for reduced edge turbulence modelling codes are discussed.

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Journal articles on the topic 'Plasma edge theory'

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