Debye screening and injection of positrons across the magnetic surfaces of a pure electron plasma in a stellarator

Durand de Gevigney, Benoit; Sunn Pedersen, Thomas; Boozer, Allen H.
January 2011
Physics of Plasmas;Jan2011, Vol. 18 Issue 1, p013508
Academic Journal
Just as quasineutral plasmas, pure electron plasmas display collective behavior and screen externally imposed electrostatic potentials. However, for pure electron plasmas, the screening of large negative potentials is fully nonlinear and deviates significantly from the textbook Debye screening. Such potentials create an evacuated region that may penetrate a long distance away from the source of the potential perturbation. An analytic model for this case is presented and compared to numerical solutions of the pure electron plasma equilibrium equation in a stellarator. Debye screening in non-neutral plasmas is asymmetric; in a pure electron plasma, negative potentials are not screened as effectively as positive potentials. Because external potentials can penetrate deep into the plasma, they can have a strong effect on particle orbit quality. Importantly, the assessment of transport driven by internal objects, e.g., diagnostic rods, depends on this. Numerical calculations are presented, showing that the poor shielding of negative potentials can be used not only to perturb and worsen confinement of a pure electron plasma, but can also be used to improve confinement modestly and can be used for injection of positrons across the magnetic surfaces in an initially pure electron plasma.


Related Articles

  • A study of solitary wave trains generated by injection of a blob into plasmas. Choi, C.-R.; Rha, K.-C.; Ryu, C.-M.; Choi, E.-J.; Min, K.-W.; Lee, E.; Parks, G. K. // Physics of Plasmas;Oct2012, Vol. 19 Issue 10, p102903 

    We have investigated the evolution of consecutive electrostatic solitary waves (ESWs) generated upon injection of a finite-sized blob into plasmas using one-dimensional electrostatic particle-in-cell simulations. Strong charge separation developed at the leading edge of the blob, producing a...

  • Three-dimensional photogrammetric measurement of magnetic field lines in the WEGA stellarator. Drewelow, Peter; Bräuer, Torsten; Otte, Matthias; Wagner, Friedrich; Werner, Andreas // Review of Scientific Instruments;Dec2009, Vol. 80 Issue 12, p123501 

    The magnetic confinement of plasmas in fusion experiments can significantly degrade due to perturbations of the magnetic field. A precise analysis of the magnetic field in a stellarator-type experiment utilizes electrons as test particles following the magnetic field line. The usual fluorescent...

  • Influence of perturbations in a magnetoplasma on the propagation of quasioptical wave beams. Balakin, A.; Gospodchikov, E. // Radiophysics & Quantum Electronics;Oct2011, Vol. 54 Issue 5, p295 

    We analyzed features of the influence of perturbations in an anisotropic medium on the propagation of quasioptical wave beams. The solutions of the quasioptical equation in the nonaberrational approximation are found, which describe the evolution of the wave-beam width. It is shown that the...

  • On the existence and stability of electrostatic structures in non-Maxwellian electron-positron-ion plasmas. Williams, G.; Kourakis, I. // Physics of Plasmas;Dec2013, Vol. 20 Issue 12, p122311 

    Electrostatic solitary waves in plasmas are the focus of many current studies of localized electrostatic disturbances in both laboratory and astrophysical plasmas. Here, an investigation of the nonlinear dynamics of plasma evolving in two dimensions, in the presence of excess superthermal...

  • Nonlinear resonance in barotropic-baroclinic transfer generated by bottom sills. Boschan, Julia; Vincze, Miklós; Jánosi, Imre M.; Tél, Tamás // Physics of Fluids;Apr2012, Vol. 24 Issue 4, p046601 

    Internal waves generated by surface perturbations are studied in a two-layer fluid in the presence of two thin sills of equal height in the lower layer, both experimentally and numerically. Small amplitude surface waves are found to generate internal waves of large amplitude at the density...

  • Ab initio study of the two lowest triplet potential energy surfaces involved in the N([sup 4]S)+NO (X [sup 2]Π) reaction. Gamallo, P.; González, Miguel; Sayós, R. // Journal of Chemical Physics;6/15/2003, Vol. 118 Issue 23, p10602 

    This work presents ab initio electronic structure calculations of the two possible N([sup 4]S)+NO(X [sup 2]Π ) abstraction reaction channels on the lowest [sup 3]A[sup ″] and [sup 3]A[sup ′] potential energy surfaces (PESs). Complete active space self-consistent-field (CASSCF)...

  • Application of advanced edge diagnostics for transport studies in the stochastic boundary of TEXTOR-DED. Schmitz, O.; Brezinsek, S.; Classen, I.; Clever, M.; Coenen, J. W.; Delabie, E.; Finken, K. H.; Jakubowski, M. W.; Kantor, M.; Krämer-Flecken, A.; Kruezi, U.; Lehnen, M.; Liang, Y.; Reiter, D.; Samm, U.; Schweer, B.; Spakman, G. W.; Stoschus, H.; Telesca, G.; Unterberg, B. // AIP Conference Proceedings;3/19/2008, Vol. 993 Issue 1, p135 

    In this paper the edge diagnostic equipment at the TEXTOR tokamak is described and its importance for detailed transport studies in the helical ergodic divertor imposed by the dynamic ergodic divertor (DED) is demonstrated. The helical ergodic divertor topology is controlled by adapting the...

  • Theory of electrostatic probe microscopy: A simple perturbative approach. Gómez-Mon˜ivas, S.; Sáenz, J. J.; Carminati, R.; Greffet, J. J. // Applied Physics Letters;5/15/2000, Vol. 76 Issue 20 

    A theoretical approach to electrostatic scanning probe microscopy is presented. We show that a simple perturbation formula, originally derived in the context of scattering theory of electromagnetic waves, can be used to obtain the capacitance and the electrostatic force between a metallic tip...

  • Reading and writing charge on graphene devices. Connolly, M. R.; Herbschleb, E. D.; Puddy, R. K.; Roy, M.; Anderson, D.; Jones, G. A. C.; Maksym, P.; Smith, C. G. // Applied Physics Letters;7/9/2012, Vol. 101 Issue 2, p023505 

    We use a combination of charge writing and scanning gate microscopy to map and modify the local charge neutrality point of graphene field-effect devices. We give a demonstration of the technique by writing remote charge in a thin dielectric layer over a graphene-metal interface and detecting a...


Read the Article


Sorry, but this item is not currently available from your library.

Try another library?
Sign out of this library

Other Topics