TITLE

The influence of rotation on the βN threshold for the 2/1 neoclassical tearing mode in DIII-D

AUTHOR(S)
Buttery, R. J.; La Haye, R. J.; Gohil, P.; Jackson, G. L.; Reimerdes, H.; Strait, E. J.
PUB. DATE
May 2008
SOURCE
Physics of Plasmas;May2008, Vol. 15 Issue 5, p056115
SOURCE TYPE
Academic Journal
DOC. TYPE
Article
ABSTRACT
Utilizing a capability to vary neutral beam torque injection in the DIII-D [J. L. Luxon, Nucl. Fusion 42, 614 (2002)] tokamak, m/n=2/1 neoclassical tearing mode onset thresholds are found to fall by about one unit in βN, from ∼3 to ∼2, in ITER-like sawtoothing high-energy confinement modes of plasma operation [R. Aymar, Plasma Phys. Control. Fusion 42, B385 (2000)] as “co-injected” torque and rotation are reduced. However, increasing levels of torque and rotation in the counter-direction do not lead to corresponding rises in βN thresholds. More encouragingly, error field sensitivity is not found to increase in low rotation plasmas, as might be expected theoretically. These results pose an interesting physics problem, as well as raising concern for future devices such as ITER. Further analyses have explored possible physics origins of the behavior. They suggest many of the usual effects expected to lead to a rotation dependence (mode coupling, wall drag, ion polarization currents) are not significant, with instead models that depend on the size and sign of rotation shear playing a role. Onset behavior suggests the mode is close to being intrinsically (classically) unstable when it appears, and a conceptual explanation is offered for a mechanism by which rotation shear feeds into the onset process through changes to the classical tearing stability index, Δ′. Further parameter extensions and studies are desirable to fully resolve the underlying physics of this interesting process.
ACCESSION #
32509516

 

Related Articles

  • Plasma kinetic theory without the Markovian approximation: I. Pocobelli, G. // Physics of Fluids (00319171);Aug86, Vol. 29 Issue 8, p2455 

    In a homogeneous plasma with no external fields, an equation of evolution for the space-averaged distribution f (v,t) is derived without making use of the Markovian approximation. The Vlasov equation is integrated for a limited, albeit arbitrary, time interval along analytical particle orbits....

  • Gyroscopic effect in compact toroidal plasmas. Geren, Preston; Steinhauer, Loren // Physics of Plasmas;Jul2004, Vol. 11 Issue 7, p3646 

    The gyroscopic effect in compact toroidal plasmas is investigated using a minimum energy principle in which the angular momentum is added as a constraint. If attention is limited to incompressible plasmas, the flow and field vectors can be expanded in eigenfunctions of the curl (Beltrami...

  • Rotating magnetic field current drive of high-temperature field reversed configurations with high ζ scaling. Guo, H. Y.; Hoffman, A. L.; Milroy, R. D. // Physics of Plasmas;Nov2007, Vol. 14 Issue 11, p112502 

    Greatly reduced recycling and impurity ingestion in the Translation, Confinement, and Sustainment—Upgrade (TCSU) device has allowed much higher plasma temperatures to be achieved in the field reversed configurations (FRC) under rotating magnetic field (RMF) formation and sustainment. The...

  • Modes and quasi-modes for m=1,2 in a gyrokinetic model for a non-neutral plasma. Rasband, S. Neil; Spencer, Ross L. // Physics of Plasmas;May99, Vol. 6 Issue 5, p1435 

    Modes and quasi-modes for m=1,2 are studied in a gyro-kinetic model for a pure-electron plasma. Only z-independent perturbations are considered. Numerical methods are used to solve the relevant differential equations for smooth, analytic density profiles. Different temperatures and...

  • Adiabatic compression and interchange stability of rotating compact toroid plasmas. Hameiri, Eliezer; Stevens, Donald C.; Grossmann, William // Physics of Fluids (00319171);Feb85, Vol. 28 Issue 2, p590 

    The adiabatic compression of plasmas with mass rotation is formulated as a variational principle based on some constants of the motion. A numerical code is constructed and Grad's alternating dimensions method is used. The calculations simulate compression either by increasing the flux outside...

  • Kinetic modeling of a two-dimensional, collisionless bounded plasma. Pedit, H.; Kuhn, S. // Physics of Plasmas;Jan1994, Vol. 1 Issue 1, p13 

    Discusses a kinetic modeling of a two-dimensional, collisionless bounded plasma. Two-dimensional Cartesian slab approximation; Validity of the guiding-center approximation used for the electrons; Equations of motion and particle trajectories.

  • A method for calculating neoclassical transport coefficients with momentum conserving collision operator. Taguchi, M. // Physics of Fluids B: Plasma Physics;Nov92, Vol. 4 Issue 11, p3638 

    A method for calculating the neoclassical transport coefficients in a nonaxisymmetric multispecies plasma is developed by employing a momentum conserving collision operator. In this method, the parallel current, and the radial particle and heat fluxes are expressed in terms of the transport...

  • Fully relativistic plasma dispersion function. Kamp, Léon P. J. // Journal of Mathematical Physics;Dec94, Vol. 35 Issue 12, p6471 

    Properties of a relativistic plasma dispersion function (PDF) that is required for the description of waves propagating perpendicular to a magnetic field in a fully relativistic, magnetized, Maxwellian plasma, are presented. Series, asymptotic series, recurrence relations, integral...

  • Collisional effects on the radio-frequency sheath dynamics. Qiu, Hua-Tan; Wang, You-Nian; Ma, Teng-Cai // Journal of Applied Physics;12/15/2001, Vol. 90 Issue 12, p5884 

    Using the hydrodynamic model, we have derived a self-consistent model describing the dynamics of a collisional rf sheath driven by a sinusoidal current source. Numerical results have been obtained for the dependence of ion density, ion kinetic energy, sheath thickness, and sheath electric field,...

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