Production and identification of the ion-temperature-gradient instability

Sen, A. K.; Chen, J; Mauel, M. E.

doi:10.1103/physrevlett.66.429

Cited by 42 publications

(33 citation statements)

References 4 publications

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“…This spectral feature correlates well with varying the heating level, as well as other signatures of an ITG slab mode. 30 It is experimentally observed to have a dominant poloidal mode number of mϭ2, a parallel wavelength of ʈ ϭ260 cm, a fluctuation level of ñ /Nϳ1% -5%, and mode width of 1cm Ϸ5 i . Figure 4 shows the measured mode width for the mϭ1 and mϭ2 poloidal mode numbers.…”

Section: Itg Modes Found In Clmmentioning

confidence: 98%

“…In addition, due to the small size of CLM and the range of unstable linearly unstable poloidal modes, there are only a few modes present in the experiment. 30,32 Here we extend the calculations of Ref. 50 to take into account that the system here ͑both experiment and simulation͒ is radially bounded and three dimensional.…”

Section: Theory Of Nonlinear Saturationmentioning

confidence: 99%

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Simulation of cylindrical ion temperature gradient modes in the Columbia Linear Machine experiment

Parker¹,

Sen²

2002

Physics of Plasmas

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A comparison of the Columbia Linear Machine experiment [A. K. Sen, J. Chen, and M. Mauel, Phys. Rev. Lett. 66, 429 (1991)] with three-dimensional nonlinear electrostatic gyrokinetic simulation results is given, as well as comparisons with linear theory and simple theoretical predictions of nonlinear saturation. Linear theory is in reasonable agreement with the both experimental and simulation results. An analysis of the radial mode width which is localized by variation in the ion temperature gradient is given and compares well with both experiment and simulation. The theoretical estimate of the nonlinear saturation level is within a factor of 2 of what is observed in experiment and in simulation. In addition, both experiment and simulation show excitation of longer wavelength modes with poloidal mode numbers smaller than the linearly most unstable mode.

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Section: Itg Modes Found In Clmmentioning

confidence: 98%

Section: Theory Of Nonlinear Saturationmentioning

confidence: 99%

Simulation of cylindrical ion temperature gradient modes in the Columbia Linear Machine experiment

Parker¹,

Sen²

2002

Physics of Plasmas

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“…[4][5][6] Such models usually predict that the ion temperature gradient ͑ITG͒ instability is the most unstable mode with the greatest associated anomalous transport in discharges which are typical for current and future generation tokamaks. Although the relevant physics of the mode has been demonstrated in other nonfusion devices, 7,8 limited direct or indirect evidence supports the dominant role of the ITG mode in tokamaks. 9,10 Given the great potential for comprehensive theoretical models to provide physics-based guidance toward a viable fusion concept, direct experimental verification of the predicted existence of the ITG mode in fusion plasmas is critically needed to reliably extrapolate performance and physics issues to large demonstration experiments in the future.…”

Section: Introductionmentioning

confidence: 95%

Search for the ion temperature gradient mode in a tokamak plasma and comparison with theoretical predictions

et al. 2001

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In recent experiments in DIII-D, comparison of specific turbulence characteristics with linear and nonlinear modeling has identified common features associated with the ion temperature gradient (ITG) mode. A low-frequency turbulence feature is observed in high-density saturated Ohmic confinement discharges, which is absent in low-density linear Ohmic confinement discharges. The feature is in a range of wavelength (k⊥ρs≈0.2–0.5) and the frequency expected for the ITG mode and onset of the feature is coincident with onset of confinement saturation. The density profile is significantly broader in the high-density discharge, a known destabilizing effect on the ITG mode. Gyrokinetic stability calculations of the growth rate of the most unstable drift ballooning mode show the ITG mode to be more unstable in the high-density discharges.

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“…[2][3][4][5] More recent studies of ITG modes have observed instability onset through variation of temperature and density gradients. 6 In this paper we argue that multispecies nonneutral plasmas provide another plasma system where such waves can be carefully studied, in a fully trapped plasma ͑disconnected from sources and sinks at the plasma ends͒, over a wide range of parameters from low temperature highly collisional ͑even strongly coupled͒ plasmas to plasmas with dimensionless parameters similar to those in fusion plasmas. Strong E ϫ B rotation of nonneutral plasmas also allows study of the effect of E ϫ B shear on instability and transport.…”

Section: Introductionmentioning

confidence: 99%

Electrostatic waves and instabilities in multispecies nonneutral plasmas

Dubin

2010

Physics of Plasmas

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This paper briefly describes waves and instabilities in a multispecies nonneutral plasma that have previously been studied only in neutral plasmas: ion sound waves, drift waves, and ion temperature gradient waves. The theory of their dispersion relations and growth rates is similar to that for neutral plasmas, but results differ in several important respects. For instance, drift waves are not necessarily unstable, the instabilities generally do not cause plasma loss, and they can be controlled (e.g., turned on or off) by manipulation of density and temperature profiles using standard experimental techniques such as centrifugal separation and laser cooling/heating. This should allow precise experimental studies of instability growth and saturation.

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Production and identification of the ion-temperature-gradient instability

Cited by 42 publications

References 4 publications

Simulation of cylindrical ion temperature gradient modes in the Columbia Linear Machine experiment

Simulation of cylindrical ion temperature gradient modes in the Columbia Linear Machine experiment

Search for the ion temperature gradient mode in a tokamak plasma and comparison with theoretical predictions

Electrostatic waves and instabilities in multispecies nonneutral plasmas

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