Effects of parallel ion motion on zonal flow generation in ion-temperature-gradient mode turbulence
- Department of Fundamental Energy Science, Graduate School of Energy Science, Kyoto University, Gokasho, Uji, Kyoto 611-0011 (Japan)
The role of parallel ion motion for zonal flow generation in ion-temperature-gradient (ITG) mode turbulence is investigated with focus on the effects of acoustic modes and toroidicity on the zonal flow. One possible reason for the weak suppression of ITG turbulence by zonal flows found in experiments in the Columbia Linear Machine [Phys. Plasmas 13, 055905 (2006)] might be due to the small toroidicity ({epsilon}{sub n}=2L{sub n}/R) in the experiment. The zonal flow is often directly dependent on the ITG mode and the coupling of zonal flow to acoustic modes and hence is directly affected by any change of the relevant parameters. The model consists of the continuity, temperature, and parallel ion momentum equations for the ITG turbulence. The zonal flow time evolution is described by a Hasegawa-Mima-like equation, and a fifth-order zonal flow dispersion relation is derived. The results are interpreted in terms of quality of zonal flows, i.e., the ratio of growth rate and real frequency (Q={omega}{sup IM}/{omega}{sup RE}). It is found that the quality of the zonal flow rapidly decreases with decreasing toroidicity.
- OSTI ID:
- 21072632
- Journal Information:
- Physics of Plasmas, Vol. 14, Issue 8; Other Information: DOI: 10.1063/1.2761861; (c) 2007 American Institute of Physics; Country of input: International Atomic Energy Agency (IAEA); ISSN 1070-664X
- Country of Publication:
- United States
- Language:
- English
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