Isotope scaling and [eta][sub [ital i]] mode with impurities in tokamak plasmas

Journal Article · Tue Nov 01 04:00:00 EST 1994 · Physics of Plasmas; (United States)

DOI:https://doi.org/10.1063/1.870942· OSTI ID:6970496

Dong, J Q; Horton, W; Dorland, W ^[1]

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1. Institute for Fusion Studies, The University of Texas at Austin, Austin, Texas 78712 (United States)

The ion temperature gradient- (ITG) driven instability, or [eta][sub [ital i]] mode, is studied for discharges with hydrogen, deuterium, or tritium in a toroidal magnetic configuration. Impurity effects on the mode and the instability (impurity mode) driven by the presence of impurity ions with negative density gradient are studied. It is found that the maximum growth rate of the [eta][sub [ital i]] mode scales as [ital M][sup [minus]1/2][sub [ital i]] for pure hydrogenic plasmas, where [ital M][sub [ital i]] is the mass number of the working gas ion. With the inclusion of impurity ions, the growth rate of the [eta][sub [ital i]] mode decreases in all three kinds of plasmas, with a hydrogen plasma still having the highest maximum growth rate, tritium the lowest, and deuterium in between. However, the isotope effects are weaker and scale as [ital M][sup [minus]1/2][sub eff] with the presence of impurity ions, where the effective mass number, [ital M][sub eff]=(1[minus][ital f][sub [ital z]])[ital M][sub [ital i]]+[ital f][sub [ital z]][ital M][sub [ital z]], with [ital M][sub [ital z]] and [ital f][sub [ital z]]= [ital Zn][sub 0[ital z]]/[ital n][sub 0[ital e]] being the mass number and charge concentration of impurity ions, respectively. For the impurity mode, the scaling is similar to that of the [eta][sub [ital i]] mode without impurity ions. The experimental database shows that the plasma energy confinement time scales as [tau][sub [ital E]][proportional to][ital M][sup 1/2][sub [ital i]] for a wide range of clean plasmas. The correlation of the theoretical results with the experimental confinement scaling is discussed.

• DOE Contract Number: FG05-80ET53088
• OSTI ID: 6970496
• Journal Information: Physics of Plasmas; (United States), Journal Name: Physics of Plasmas; (United States) Vol. 1:11; ISSN PHPAEN; ISSN 1070-664X
• Country of Publication: United States
• Language: English

Related Subjects

70 PLASMA PHYSICS AND FUSION TECHNOLOGY
700310 -- Plasma Confinement-- (1992-)
700340* -- Plasma Waves
Oscillations
& Instabilities-- (1992-)
BETA DECAY RADIOISOTOPES
BETA-MINUS DECAY RADIOISOTOPES
CLOSED PLASMA DEVICES
CONFINEMENT
DEUTERIUM
DISPERSION RELATIONS
ELEMENTS
HYDROGEN
HYDROGEN ISOTOPES
IMPURITIES
INSTABILITY GROWTH RATES
ION TEMPERATURE
ISOTOPE EFFECTS
ISOTOPES
LIGHT NUCLEI
NONMETALS
NUCLEI
ODD-EVEN NUCLEI
ODD-ODD NUCLEI
PLASMA CONFINEMENT
PLASMA DRIFT
PLASMA IMPURITIES
RADIOISOTOPES
SCALING LAWS
STABLE ISOTOPES
THERMONUCLEAR DEVICES
TOKAMAK DEVICES
TRITIUM
YEARS LIVING RADIOISOTOPES