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

Abstract

The generalized accessibility of lower hybrid waves, primarily in the current drive regime of tokamak plasmas, which may include shifting, either upward or downward, of the parallel refractive index (n{sub {parallel}}), is investigated, based upon a cold plasma dispersion relation and various geometrical constraint (G.C.) relations imposed on the behavior of n{sub {parallel}}. It is shown that n{sub {parallel}} upshifting can be bounded and insufficient to bridge a large spectral gap to cause wave damping, depending upon whether the G.C. relation allows the oblique resonance to occur. The traditional n{sub {parallel}} upshifting mechanism caused by the pitch angle of magnetic field lines is shown to lead to contradictions with experimental observations. An upshifting 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 {open_quote}seed electrons.{close_quote}

Authors:
Publication Date:
Research Org.:
Princeton Univ., NJ (United States). Plasma Physics Lab.
Sponsoring Org.:
USDOE, Washington, DC (United States)
OSTI Identifier:
10141658
Report Number(s):
PPPL-2947
ON: DE94009828; TRN: 94:007589
DOE Contract Number:  
AC02-76CH03073
Resource Type:
Technical Report
Resource Relation:
Other Information: PBD: Mar 1994
Country of Publication:
United States
Language:
English
Subject:
70 PLASMA PHYSICS AND FUSION TECHNOLOGY; TOKAMAK DEVICES; LOWER HYBRID CURRENT DRIVE; PLASMA WAVES; WAVE PROPAGATION; DISPERSION RELATIONS; 700340; 700460; PLASMA WAVES, OSCILLATIONS, AND INSTABILITIES; HEATING AND FUELING SYSTEMS; FUELS

Citation Formats

Takahashi, Hironori. The generalized accessibility and spectral gap of lower hybrid waves in tokamaks. United States: N. p., 1994. Web. doi:10.2172/10141658.
Takahashi, Hironori. The generalized accessibility and spectral gap of lower hybrid waves in tokamaks. United States. doi:10.2172/10141658.
Takahashi, Hironori. Tue . "The generalized accessibility and spectral gap of lower hybrid waves in tokamaks". United States. doi:10.2172/10141658. https://www.osti.gov/servlets/purl/10141658.
@article{osti_10141658,
title = {The generalized accessibility and spectral gap of lower hybrid waves in tokamaks},
author = {Takahashi, Hironori},
abstractNote = {The generalized accessibility of lower hybrid waves, primarily in the current drive regime of tokamak plasmas, which may include shifting, either upward or downward, of the parallel refractive index (n{sub {parallel}}), is investigated, based upon a cold plasma dispersion relation and various geometrical constraint (G.C.) relations imposed on the behavior of n{sub {parallel}}. It is shown that n{sub {parallel}} upshifting can be bounded and insufficient to bridge a large spectral gap to cause wave damping, depending upon whether the G.C. relation allows the oblique resonance to occur. The traditional n{sub {parallel}} upshifting mechanism caused by the pitch angle of magnetic field lines is shown to lead to contradictions with experimental observations. An upshifting 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 {open_quote}seed electrons.{close_quote}},
doi = {10.2172/10141658},
journal = {},
number = ,
volume = ,
place = {United States},
year = {1994},
month = {3}
}