A possible hybrid dissipative trapped electron ion temperature gradient mode

Journal Article · Thu Aug 01 04:00:00 EDT 1996 · Physics of Plasmas

DOI:https://doi.org/10.1063/1.871635· OSTI ID:286352

Bai, L; Qiu, X M; Huang, L; Song, X M ^[1]

---

1. Southwestern Institute of Physics, P.O. Box 432, Chengdu 610041, People`s Republic of (China)

The effects of dissipative trapped electrons on ion temperature gradient-driven instability ({eta}{sub {ital i}} mode) in tokamak plasmas are considered. A sheared slab geometry is adopted and a linearized fluid model of ion temperature gradient (ITG) mode including dissipative trapped electrons, which are described by means of the well-known formula of the nonadiabatic electron response [P. L. Similon and P. H. Diamond, Phys. Fluids {bold 27}, 916 (1984)], is presented. Results show that in tokamak plasmas not only is there a modification of the dissipative trapped electrons on the {eta}{sub {ital i}} mode, but also there may exist an intrinsic oscillation mode, namely, a hybrid dissipative trapped electron ion temperature gradient mode. The higher the dissipative trapped electron fraction, the more it drives the {eta}{sub {ital i}} mode, that is, when the trapped electron fraction is sufficient high and the trapped electrons are dissipated strongly, the mode is dominated by the trapped electron dynamics and propagates in the electron diamagnetic direction. These analytical results can be reduced to the usual predictions of the ion temperature gradient-driven instability in the absence of the dissipative trapped electron. Numerical results further show that (a) there may be a hybrid dissipative trapped electron ITG mode and the dissipative trapped electron effect is a destabilizing effect on this mode; and (b) when the trapped electron fraction is sufficiently high and the trapped electrons are dissipated strongly, the mode is determined by the trapped electron dynamics. These conclusions are in agreement with the experimental observations in the latest simulated tokamak experiment on the Columbia Linear Machine [J. Chen and A. K. Sen, Phys. Rev. Lett. {bold 72}, 3997 (1994)]. {copyright} {ital 1996 American Institute of Physics.}

• OSTI ID: 286352
• Journal Information: Physics of Plasmas, Journal Name: Physics of Plasmas Journal Issue: 8 Vol. 3; ISSN PHPAEN; ISSN 1070-664X
• Country of Publication: United States
• Language: English

Related Subjects

70 PLASMA PHYSICS AND FUSION TECHNOLOGY
DRIFT INSTABILITY
ION TEMPERATURE
PLASMA DRIFT
TEMPERATURE GRADIENTS
TEXT DEVICES
TOKAMAK DEVICES
TRAPPED ELECTRONS