Electric potential differences across auroral generator interfaces

Keyser, Johan De; Echim, Marius

doi:10.5194/angeo-31-251-2013

Cited by 15 publications

(19 citation statements)

References 27 publications

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“…The indeterminacy inherent in one-dimensional tangential discontinuities becomes explicit in the models proposed by Sestero (1964Sestero ( , 1966, Roth et al (1996), and De Keyser and Echim (2013) and in the present paper in the arbitrariness of the choice of distribution functions, and of the cutoff functions in particular. We have already cited observational studies that support at least the qualitative correctness of these models.…”

Section: Discussionmentioning

confidence: 69%

“…This conclusion is strongly related to the effects of external electric potential difference and flow shear across individual planar TD interfaces (De Keyser et al, 1997;De Keyser and Echim, 2013). Such existence limits are absent in models that are restricted to exactly neutral plasma slabs (e.g.…”

Section: Discussionmentioning

confidence: 99%

“…The question of the existence of an individual TD under shear flow conditions has been studied previously in considerable detail (Sestero, 1966;De Keyser et al, 1997;De Keyser and Echim, 2013). These studies have demonstrated that there is a distinct asymmetry in the size of the existence domain, depending on the sense of the flow shear.…”

Section: Cross-field Flowmentioning

confidence: 98%

“…The structure of TD interfaces has been studied in detail by Harris (1962), Nicholson (1963), Sestero (1964), Sestero (1966), Whipple et al (1984), Roth et al (1996), Mottez (2003), De Keyser and Echim (2013) and others. The guiding centre of each particle in a one-dimensional planar TD stays at a constant distance from the interface.…”

Section: Velocity Distribution Functionsmentioning

confidence: 99%

“…In general φ max increases with the temperature of the hot ions (see, e.g., De Keyser and Echim, 2013), so that the range of V 0y for which an equilibrium exists becomes correspondingly larger.…”

Section: Cross-field Flowmentioning

confidence: 99%

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Cross-field flow and electric potential in a plasma slab

2013

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We consider cross-field plasma flow inside a field-aligned plasma slab embedded in a uniform background in a 1-dimensional geometry. This situation may arise, for instance, when long-lasting reconnection pulses inject plasma into the inner magnetosphere. The present paper presents a detailed analysis of the structure of the interfaces that separate the slab from the background plasma on either side; a fully kinetic model is used to do so. Since the velocity shear across both interfaces has opposite signs, and given the typical gyroradius differences between injected and background ions and electrons, the structure of both interfaces can be very different. The behaviour of the slab and its interfaces depends critically on the flow of the plasma transverse to the magnetic field; in particular, it is shown that there are bounds to the flow speed that can be supported by the magnetised plasma. Further complicating the picture is the effect of the potential difference between the slab and its environment

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Section: Discussionmentioning

confidence: 69%

Section: Discussionmentioning

confidence: 99%

Section: Cross-field Flowmentioning

confidence: 98%

Section: Velocity Distribution Functionsmentioning

confidence: 99%

Section: Cross-field Flowmentioning

confidence: 99%

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Cross-field flow and electric potential in a plasma slab

2013

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The dependence of the strength and thickness of field‐aligned currents on solar wind and ionospheric parameters

Johnson

Wing

2015

JGR Space Physics

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Sheared plasma flows at the low-latitude boundary layer (LLBL) correlate well with early afternoon auroral arcs and upward field-aligned currents. We present a simple analytic model that relates solar wind and ionospheric parameters to the strength and thickness of field-aligned currents (Λ) in a region of sheared velocity, such as the LLBL. We compare the predictions of the model with DMSP observations and find remarkably good scaling of the upward region 1 currents with solar wind and ionospheric parameters in region located at the boundary layer or open field lines at 1100-1700 magnetic local time. We demonstrate that Λ ∼ n −0.5 sw and Λ ∼ L when Λ∕L < 5 where L is the auroral electrostatic scale length. The sheared boundary layer thickness (Δ m ) is inferred to be around 3000 km, which appears to have weak dependence on V sw . J ∥ has dependencies on Δ m , Σ p , n sw , and V sw . The analytic model provides a simple way to organize data and to infer boundary layer structures from ionospheric data.

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Theory and observations of upward field‐aligned currents at the magnetopause boundary layer

Wing

2015

Geophysical Research Letters

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The dependence of the upward field‐aligned current density (J||) at the dayside magnetopause boundary layer is well described by a simple analytic model based on a velocity shear generator. A previous observational survey confirmed that the scaling properties predicted by the analytical model are applicable between 11 and 17 MLT. We utilize the analytic model to predict field‐aligned currents using solar wind and ionospheric parameters and compare with direct observations. The calculated and observed parallel currents are in excellent agreement, suggesting that the model may be useful to infer boundary layer structures. However, near noon, where velocity shear is small, the kinetic pressure gradients and thermal currents, which are not included in the model, could make a small but significant contribution to J||. Excluding data from noon, our least squares fit returns log(J||,max_cal) = (0.96 ± 0.04) log(J||_obs) + (0.03 ± 0.01) where J||,max_cal = calculated J||,max and J||_obs = observed J||.

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Electric potential differences across auroral generator interfaces

Cited by 15 publications

References 27 publications

Cross-field flow and electric potential in a plasma slab

Cross-field flow and electric potential in a plasma slab

The dependence of the strength and thickness of field‐aligned currents on solar wind and ionospheric parameters

Theory and observations of upward field‐aligned currents at the magnetopause boundary layer

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