Universal Instability in a Fully Ionized Inhomogeneous Plasma

Lashinsky, H.

doi:10.1103/physrevlett.12.121

Cited by 50 publications

(14 citation statements)

References 5 publications

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“…A large number of works have been devoted to their study since the early 1960s. [4][5][6][19][20][21][22] In a cylindrical column, where there is a radial density gradient, their propagation is mainly azimuthal, but one important feature is that this propagation has also an axial component. Their dynamics is characterized by a strong coupling between the movement of the electrons along the magnetic field lines and the movement of the ions in the transverse direction.…”

Section: Drift Waves and Rotation Induced Instabilitiesmentioning

confidence: 99%

“…For this reason, low frequency instabilities have attracted much attention for decades. [4][5][6][7] In linear magnetized plasma devices, without curvature or magnetic field gradient, turbulence is often believed to arise from diamagnetic drift waves regimes. 6,8 However, the E ϫ B plasma rotation due to the mean radial electric field is likely to trigger flute modes as well, especially when a limiter reduces the plasma diameter.…”

Section: Introductionmentioning

confidence: 99%

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Transition from flute modes to drift waves in a magnetized plasma column

2005

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Recent experiments performed on the low β plasma device Mirabelle [T. Pierre, G. Leclert, and F. Braun, Rev. Sci. Instrum. 58, 6 (1987)] using a limiter have shown that transitions between various gradient driven instabilities occurred on increasing the magnetic field strength. New thorough measurements allow to identify unambiguously three instability regimes. At low magnetic field the strong E×B velocity shear drives a Kelvin–Helmholtz instability, whereas at high magnetic field drift waves are only observed. A centrifugal (Rayleigh–Taylor) instability is also observed in between when the E×B velocity is shearless and strong enough. A close connection is made between the ratio ρs∕L⊥ of the drift parameter to the radial density gradient length and each instability regime.

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Section: Drift Waves and Rotation Induced Instabilitiesmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Transition from flute modes to drift waves in a magnetized plasma column

2005

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“…This is well known in terms of the resistive drift instability. [22][23][24][25][26][27][28][29] Density perturbations will tend to travel azimuthally (y direction͒ at the diamagnetic drift speed v D . In the absence of electron collisions ϭ, the first-order potential will oscillate in phase with the density perturbation creating a stable drift wave.…”

Section: ͑19͒mentioning

confidence: 99%

Low frequency electrostatic instability in a helicon plasma

2001

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Recent discoveries in a helicon plasma show a decrease in equilibrium plasma density as magnetic field strength is increased. This can be explained in the framework of a low frequency electrostatic instability. However, quiescent plasma behavior in helicon sources has been hitherto accepted. To verify the existence of an instability, extensive measurements of fluctuating quantities and losses as a function of magnetic field were implemented. Furthermore, a theoretical model was developed to compare to the measurements. Theory and measurement show very good agreement; both verifying the existence of a low frequency instability and showing that it is indeed responsible for the observed density characteristic.

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“…The subject of fluctuations driven by edge plasma gradients near a conducting wall has been extensively investigated in the laboratory, primarily in the electrostatic domain accessible to small Q-machine plasma columns, [20][21][22][23] and to a more limited extent in tokamak devices 24,25 where both magnetic and density fluctuations are simultaneously present. Small, high-density arcs 26 have also been used to study edge plasma drift-Alfvén waves while global drift-Alfvén waves have been identified 27 in laboratory toroidal devices.…”

Section: Comparison To Edge Fluctuationsmentioning

confidence: 99%

Fluctuations associated with a filamentary density depletion

Maggs

Morales

1997

Physics of Plasmas

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Density and magnetic fluctuations arising spontaneously in a narrow field-aligned density striation in a magnetized discharge He plasma are found to exhibit a radial eigenmode structure. The nature of the fluctuations depends upon the electron plasma beta, ␤ e. For ␤ e greater than the electron to ion mass ratio (␤ e Ͼm/M) the frequency spectrum exhibits sharply peaked eigenfrequencies with the density and magnetic fluctuations strongly coupled so that the growing mode is identified as the drift-Alfvén wave. For ␤ e less than the mass ratio (␤ e Ͻm/M) the density and magnetic fluctuations separate in frequency and broadband magnetic shear Alfvén wave turbulence develops. The driving source for the fluctuations is the cross-field density and temperature gradients in the edge of the striation which have scale lengths on the order of the electron skin depth. The fluctuations associated with the striation are compared to the edge fluctuations of the plasma column which are found to exhibit a universal exponential frequency spectrum.

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Universal Instability in a Fully Ionized Inhomogeneous Plasma

Cited by 50 publications

References 5 publications

Transition from flute modes to drift waves in a magnetized plasma column

Transition from flute modes to drift waves in a magnetized plasma column

Low frequency electrostatic instability in a helicon plasma

Fluctuations associated with a filamentary density depletion

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