TITLE

Loss of confinement at the density limit due to the suppression of stabilizing zonal flows by magnetic turbulence

AUTHOR(S)
Kleva, Robert G.; Guzdar, Parvez N.
PUB. DATE
August 2008
SOURCE
Physics of Plasmas;Aug2008, Vol. 15 Issue 8, p082307
SOURCE TYPE
Academic Journal
DOC. TYPE
Article
ABSTRACT
The character of particle and energy transport in numerical simulations of drift-ballooning turbulence changes dramatically as the density exceeds a critical limit. When the density is not too large, then unstable drift-ballooning fluctuations grow and nonlinearly generate a sheared zonal (flux surface averaged) flow that saturates the turbulence. But when diamagnetic drift effects are small and the density increases beyond a critical limit, then the turbulent density flux increases monotonically in time to large values without saturation. This loss of confinement is caused by the suppression of the stabilizing zonal flow by the magnetic component of the turbulence. A Kelvin–Helmholtz-like shear-flow instability does not play any role in reducing the magnitude of the zonal flow. The magnetic turbulence prevents the zonal flow from growing large enough to become shear-flow unstable.
ACCESSION #
34169254

 

Related Articles

  • Lower hybrid turbulence driven by parallel currents and associated electron energization. McMillan, Ben F.; Cairns, Iver H. // Physics of Plasmas;May2006, Vol. 13 Issue 5, p056701 

    Parallel currents are usually in the form of field-aligned electron drifts in collisionless plasmas. The field-aligned drifts often drive instabilities. For instance, Drake et al. [Science, 299, 873 (2003)] found growth of parallel propagating turbulence initially and strong levels of oblique...

  • Computational investigation of the magneto-Rayleigh–Taylor instability in Z-pinch implosions. Zhang Yang; Wu Jiming; Dai Zihuan; Ding Ning; Ning Cheng; Yao Yanzhong; Xiao Delong; Sun Shunkai; Gu Tongxiang; Cao Yi; Huang Jun; Xue Chuang; Shu Xiaojian // Physics of Plasmas;Apr2010, Vol. 17 Issue 4, p042702 

    The instability evolvement induced by single mode and random density seeds have been investigated by using the Magnetics Atom Radiation Electron Dynamics (MARED) code, which is a two dimensional, three temperature, radiation magnetohydrodynamic Lagrangian code developed for the Z-pinch implosion...

  • Collision and average velocity effects on the ratchet pinch. Vlad, M.; Spineanu, F.; Benkadda, S. // Physics of Plasmas;Mar2008, Vol. 15 Issue 3, p032306 

    A ratchet-type average velocity VR appears for test particles moving in a stochastic potential and a magnetic field that is space dependent. This model is developed by including particle collisions and an average velocity. We show that these components of the motion can destroy the ratchet...

  • Confinement of plasmas of arbitrary neutrality in a stellarator. Pedersen, Thomas Sunn; Boozer, Allen H.; Kremer, Jason P.; Lefrancois, Remi // Physics of Plasmas;May2004, Vol. 11 Issue 5, p2377 

    The equilibrium, stability, and transport of pure electron plasmas confined on magnetic surfaces is reviewed. The prospects for creation of partly neutralized plasmas and electron-positron plasmas confined in a stellarator are discussed. The Columbia Non-neutral Torus, a small ultrahigh vacuum...

  • Magnetohydrodynamic dynamo in reversed field pinch plasmas: Electrostatic drift nature of the dynamo velocity field. Cappello, S.; Bonfiglio, D.; Escande, D. F. // Physics of Plasmas;May2006, Vol. 13 Issue 5, p058102 

    Within the framework of magnetohydrodynamic (MHD) numerical modeling, the reversed field pinch (RFP) has been found to develop turbulent or laminar regimes switching from the former to the latter in a continuous way when the strength of dissipative forces increases. The laminar solution...

  • Numerical study of the dynamics of Z-pinch carbon plasmas. Lee, K.T.; Kim, S.H.; Kim, D.; Lee, T.N. // Physics of Plasmas;Apr96, Vol. 3 Issue 4, p1340 

    Investigates the dynamics of Z-pinch carbon plasma using one-dimensional Lagrangian code. Calculation of the single-fluid, two-temperature magnetohydrodynamic equations coupled with an ionization balance equation; Motion of plasma column and shock front; Effect of the radiative trapping of...

  • The effect of sheared axial flow on the linear stability of the Z-pinch. Arber, T.D.; Howell, D.F. // Physics of Plasmas;Feb96, Vol. 3 Issue 2, p554 

    Presents a linear analysis of the ideal magnetohydrodynamic stability of the Z-pinch in which plasma flows are included in the equilibrium. Substantial stabilization of internal modes for some equilibrium profiles; Basic equations and boundary conditions; Equation for Z-pinch equilibria...

  • Ideal internal kink modes in a differentially rotating cylindrical plasma. Mikhailovskii, A. B.; Lominadze, J. G.; Galvão, R. M. O.; Churikov, A. P.; Erokhin, N. N.; Pustovitov, V. D.; Konovalov, S. V.; Smolyakov, A. I.; Tsypin, V. S. // Plasma Physics Reports;Jul2008, Vol. 34 Issue 7, p538 

    The Velikhov effect leading to magnetorotational instability (MRI) is incorporated into the theory of ideal internal kink modes in a differentially rotating cylindrical plasma column. It is shown that this effect can play a stabilizing role for suitably organized plasma rotation profiles,...

  • Edge and scrape-off layer tokamak plasma turbulence simulation using two-field fluid model. Bisai, Nirmal; Das, Amita; Deshpande, Shishir; Jha, Ratneshwar; Kaw, Predhiman; Sen, Abhijit; Singh, Raghvendra // Physics of Plasmas;Jul2005, Vol. 12 Issue 7, p072520 

    A novel two-dimensional (2D) fluid model is proposed for investigating flux-driven plasma turbulence in the tokamak edge and scrape-off layer (SOL). Unlike most previous turbulence simulations of this region, the 2D model treats the two regions in a consolidated manner with a smooth transition...

Share

Read the Article

Courtesy of THE LIBRARY OF VIRGINIA

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

Try another library?
Sign out of this library

Other Topics