Влияние градиента концентрации плазмы на возбуждение ионно-циклотронных колебаний в омических разрядах токамака ТУМАН-3М

In TUMAN-3M tokamak ohmic hydrogen and deuterium discharges oscillations with ion cyclotron (IC) frequency were detected. Fast magnetic probes poloidal array in TUMAN-3M is capable of detecting several harmonics of IC frequency of main plasma isotope. Fuel pellet injection significantly reduces IC oscillations intensity, though after complete pellet evaporation returns to initial level. IC oscillations localization and excitation conditions are of certain interest. Based on drift-cyclotron instability excitation theory and numerical modeling of scenarios with ohmic LH-transition and pellet-injection plasma parameters (density gradient primarily) effect on IC oscillations excitation was studied.

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Electromagnetic ion-cyclotron instability vs. electrostatic ion-cyclotron instability in mixed (warm-cold) magnetospheric-like plasmas

Journal of Plasma Physics ◽

10.1017/s0022377800023473 ◽

1977 ◽

Vol 18 (3) ◽

pp. 391-413 ◽

Cited By ~ 18

Author(s):

S. Cuperman ◽

L. Gomberoff

Keyword(s):

Electromagnetic Coupling ◽

Maximum Growth ◽

Systematic Investigation ◽

Maximum Growth Rate ◽

Plasma Parameters ◽

Loss Cone ◽

Cyclotron Instability ◽

Ion Cyclotron ◽

Validity Range ◽

Approximate Expressions

This work presents a systematic investigation and comparison of electromagnetic ion-cyclotron (e.m.) and electrostatic ion-cyclotron (e.s.) instabilities in uniform mixed warm and cold plasmas for magnetospheric-like plasma parameters. The following main aspects are included: Analytical: (i) we derive simple approximate expressions for the maximum growth rate, γmax for the quasi-electrostatic instability in the regime ωr » …p, к┴ » к∥ (к∥ ≠ 0) with the protons being described by mixed loss-cone and cold populations and with inclusion of electromagnetic coupling effects due to electrons; (ii) we analyse another regime in which electrostatic instalilities first increase with addition of cold plasma and decrease only after having reached a maximum, namely a regime with ωr » …p, к = к≠; (iii) we summarize the corresponding analytical results for parallel propagating electromagnetic ion-cyclotron unstable waves and discuss their validity range.

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Current driven electromagnetic ion cyclotron instability

Journal of Plasma Physics ◽

10.1017/s0022377800021693 ◽

1979 ◽

Vol 21 (1) ◽

pp. 127-139 ◽

Cited By ~ 47

Author(s):

D. W. Forslund ◽

J. M. Kindel ◽

M. A. Stroscio

Keyword(s):

Magnetic Field ◽

Drift Velocity ◽

Electron Distribution ◽

Collisionless Plasma ◽

Larmor Radius ◽

Electron Drift ◽

Thermal Velocity ◽

Plasma Parameters ◽

Cyclotron Instability ◽

Ion Cyclotron

When an electron distribution drifts relative to the ions along a d.c. magnetic field, it is known that, above some critical drift velocity, a nearly field-aligned electromagnetic ion cyclotron instability may be excited. We extend the study of this instability over wide variations in plasma parameters, ion β in particular, and beyond marginal stability.Above threshold the most unstable waves propagate very obliquely to the ambient d.c. magnetic field at wavenumbers of the order of an inverse ion Larmor radius. At low ion β the critical electron drift normalized to the ion thermal velocity scales inversely as β i- ½ while, for β i>10-2, the critical drift scales as the ion thermal velocity. For the Te≈Tielectromagnetic ion cyclotron instabifity begins to have a lower threshold than the corresponding electrostatic instability at β i≈me/Mi. In a moderately high β i, homogeneous, collisionless plasma the electromagnetic ion cyclotron instability appears to have the lowest threshold of any current driven instability.

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