The generalized accessibility and spectral gap of lower hybrid waves in tokamaks

Journal Article · Fri Jul 01 04:00:00 EDT 1994 · Physics of Plasmas; (United States)

DOI:https://doi.org/10.1063/1.870624· OSTI ID:7295778

Takahashi, H ^[1]

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1. Plasma Physics Laboratory, Princeton University, Princeton, New Jersey 08544 (United States)

The generalized accessibility of lower hybrid waves, which may include shifting of the parallel refractive index ([ital n][sub [parallel]]), either upward or downward, is investigated, using the cold plasma dispersion relation and various geometrical constraint (GC) relations imposed on the behavior of [ital n][sub [parallel]]. It is shown that [ital n][sub [parallel]] upshifting is bounded and can be insufficient to bridge a large spectral gap to cause wave damping, if the GC relation does not allow the oblique resonance to occur. The traditional [ital n][sub [parallel]] upshift mechanism based upon the pitch angle of magnetic field lines is shown to lead to contradictions with experimental observations. An upshift mechanism brought about by the density gradient along field lines is proposed, which is not inconsistent with experimental observations, and provides plausible explanations to some unresolved issues of lower hybrid wave theory, including generation of seed electrons.'

• DOE Contract Number: AC02-76CH03073
• OSTI ID: 7295778
• Journal Information: Physics of Plasmas; (United States), Journal Name: Physics of Plasmas; (United States) Vol. 1:7; ISSN PHPAEN; ISSN 1070-664X
• Country of Publication: United States
• Language: English

Related Subjects

70 PLASMA PHYSICS AND FUSION TECHNOLOGY
700340* -- Plasma Waves
Oscillations
& Instabilities-- (1992-)
700350 -- Plasma Production
Heating
Current Drive
& Interactions-- (1992-)
CLOSED PLASMA DEVICES
COLD PLASMA
DISPERSION RELATIONS
LOWER HYBRID CURRENT DRIVE
NON-INDUCTIVE CURRENT DRIVE
OPTICAL PROPERTIES
PHYSICAL PROPERTIES
PLASMA
REFRACTIVE INDEX
RESONANCE
THERMONUCLEAR DEVICES
TOKAMAK DEVICES