Full wave simulations of lower hybrid wave propagation in tokamaks

Journal Article · Thu Nov 26 00:00:00 EST 2009 · AIP Conference Proceedings

DOI:https://doi.org/10.1063/1.3273765· OSTI ID:21335742

Wright, J C; Bonoli, P T ^[1]; Phillips, C K; Valeo, E ^[2]; Harvey, R W ^[3]

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1. MIT-Plasma Science and Fusion Center Cambridge, MA 02139 (United States)
2. Princeton Plasma Physics Laboratory-Princeton, New Jersey (United States)
3. Comp-X-Del Mar, CA 92014 (United States)

Lower hybrid (LH) waves have the attractive property of damping strongly via electron Landau resonance on relatively fast tail electrons at (2.5-3)xv{sub te}, where v{sub te} {identical_to} (2T{sub e}/m{sub e}){sup 1/2} is the electron thermal speed. Consequently these waves are well-suited to driving current in the plasma periphery where the electron temperature is lower, making LH current drive (LHCD) a promising technique for off-axis (r/a{>=}0.60) current profile control in reactor grade plasmas. Established techniques for computing wave propagation and absorption use WKB expansions with non-Maxwellian self-consistent distributions.In typical plasma conditions with electron densities of several 10{sup 19} m{sup -3} and toroidal magnetic fields strengths of 4 Telsa, the perpendicular wavelength is of the order of 1 mm and the parallel wavelength is of the order of 1 cm. Even in a relatively small device such as Alcator C-Mod with a minor radius of 22 cm, the number of wavelengths that must be resolved requires large amounts of computational resources for the full wave treatment. These requirements are met with a massively parallel version of the TORIC full wave code that has been adapted specifically for the simulation of LH waves [J. C. Wright, et al., Commun. Comput. Phys., 4, 545 (2008), J. C. Wright, et al., Phys. Plasmas 16 July (2009)]. This model accurately represents the effects of focusing and diffraction that occur in LH propagation. It is also coupled with a Fokker-Planck solver, CQL3D, to provide self-consistent distribution functions for the plasma dielectric as well as a synthetic hard X-ray (HXR) diagnostic for direct comparisons with experimental measurements of LH waves.The wave solutions from the TORIC-LH zero FLR model will be compared to the results from ray tracing from the GENRAY/CQL3D code via the synthetic HXR diagnostic and power deposition.

• OSTI ID: 21335742
• Journal Information: AIP Conference Proceedings, Vol. 1187, Issue 1; Conference: 18. topical conference on radio frequency power in plasmas, Gent (Belgium), 24-26 Jun 2009; Other Information: DOI: 10.1063/1.3273765; (c) 2009 American Institute of Physics; Country of input: International Atomic Energy Agency (IAEA); ISSN 0094-243X
• Country of Publication: United States
• Language: English

Related Subjects

70 PLASMA PHYSICS AND FUSION TECHNOLOGY
ALCATOR DEVICE
COMPARATIVE EVALUATIONS
COMPUTERIZED SIMULATION
DAMPING
DISTRIBUTION FUNCTIONS
ELECTRON DENSITY
ELECTRON TEMPERATURE
FOKKER-PLANCK EQUATION
G CODES
HARD X RADIATION
LOWER HYBRID CURRENT DRIVE
LOWER HYBRID HEATING
MAGNETIC FIELDS
PLASMA
PLASMA DIAGNOSTICS
PLASMA SIMULATION
TAIL ELECTRONS
WAVE PROPAGATION