The role of high frequency oscillations in the penetration of plasma clouds across magnetic boundaries

Hurtig, Tomas; Brenning, Nils; Raadu, Michael A.

doi:10.1063/1.1812276

Cited by 22 publications

(43 citation statements)

References 34 publications

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“…Without assuming anything about the physical nature of the waves in the experiment, or about the driving mechanism behind, we will directly from measured wave data demonstrate their role in the magnetic diffusion process. In another publication [3] we have shown that the modified two-stream instability, MTSI, driven by a diamagnetic current loop, agrees quite well with the wave data and probably is the operating mechanism in this particular case. …”

supporting

confidence: 71%

“…2 and described in [3]. Typical parameters are: B = 0,015T, n e = 10 18 -10 19 m -3 , T e = 5-10eV, W i = 200 -2000eV, stream velocity 2 -6x10 5 m/s, and stream width w = 0,1m.…”

Section: The Experiments and Diagnosticsmentioning

confidence: 99%

“…The middle panel of Fig. 3 shows the magnetic field component B y as function of time, measured by a multi-probe array spaced along the x axis at y = z = 0, immediately after the magnetic transition [3]. The transverse (B y ) component has already here penetrated the plasmoid by about 70% (notice that the diamagnetic reduction of the magnetic field inside the plasmoid shows up as a peak in Fig.…”

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confidence: 99%

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The penetration of plasma clouds across magnetic boundaries: The role of high frequency oscillations

2004

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Experiments are reported where a collisionfree plasma cloud penetrates a magnetic barrier by self-polarization. We here focus on the resulting anomalous magnetic field diffusion into the plasma cloud, two orders of magnitude faster than classical, which is one important aspect of the plasma cloud penetration mechanism. Without such fast magnetic diffusion, clouds with kinetic β k below unity would not be able to penetrate magnetic barriers at all. Tailor-made diagnostics has been used for measurements in the parameter range with the kinetic β k ≈ 0.5 to 10, and with normalized width w/r gi of the order of unity. Experimental data on hf fluctuations in density and in electric field has been combined to yield the effective anomalous transverse resistivity η EFF . It is concluded that they are both dominated by highly nonlinear oscillations in the lower hybrid range, driven by a strong diamagnetic current loop that is set up in the plasma in the penetration process. The anomalous magnetic diffusion rate, calculated from the resistivity η EFF , is consistent with single-shot multi-probe array measurements of the diamagnetic cavity and the associated quasi-dc electric structure. An interpretation of the instability measurements in terms of the resistive term in the generalized (low frequency) Ohm's law is given.

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supporting

confidence: 71%

“…2 and described in [3]. Typical parameters are: B = 0,015T, n e = 10 18 -10 19 m -3 , T e = 5-10eV, W i = 200 -2000eV, stream velocity 2 -6x10 5 m/s, and stream width w = 0,1m.…”

Section: The Experiments and Diagnosticsmentioning

confidence: 99%

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confidence: 99%

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The penetration of plasma clouds across magnetic boundaries: The role of high frequency oscillations

2004

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“…At t=0.75T Li , the front side region of the cloud moved across the magnetic discontinuity. Some internal density variability is observed, a possible effect of internal waves and instabilities, but the cloud preserves its overall shape and convects as a coherent structure; for a discussion on highfrequency oscillations related to the transport of plasma clouds across magnetic barriers, see the papers of Hurtig et al (2005) and Brenning et al (2005). The xOz cross-section shows that the cloud also expands in the direction of the background magnetic field and its density decreases accordingly (see the right column of Figure 3).…”

Section: Case A: Open Magnetic Barriermentioning

confidence: 99%

“…Also, the lateral "wings" of the plasma element, localized around y≈65 and y≈160, are characterized by a strong negative electric field and electric drift velocity. The electric field fluctuations observed within the current position of plasma element are most probably related to simulation noise; see Hurtig et al (2005) and Brenning et al (2005) for discussions on high-frequency oscillations related to the transport of plasma across magnetic barriers.…”

Section: Case C: Closed Magnetic Barriermentioning

confidence: 99%

Transport and entry of plasma clouds/jets across transverse magnetic discontinuities: Three‐dimensional electromagnetic particle‐in‐cell simulations

Voitcu

Echim

2016

JGR Space Physics

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In this paper we use three‐dimensional electromagnetic particle‐in‐cell simulations to investigate the interaction of a small Larmor radius plasma cloud/jet with a transverse nonuniform magnetic field typical to a tangential discontinuity in a parallel geometry. The simulation setup corresponds to an idealized, yet relevant, magnetospheric configuration likely to be observed at the magnetopause during northward orientation of the interplanetary magnetic field. The numerical simulations are adapted to study the kinetic effects and their role on the transport and entry of localized plasma jets similar to those identified inside the Earth's magnetosheath propagating toward the magnetopause. The simulations reveal the formation of a perpendicular polarization electric field inside the main bulk of the plasma cloud that enables its forward transport and entry across the transverse magnetic field. The jet is able to penetrate the transition region when the height of the magnetic barrier does not exceed a certain critical threshold. Otherwise, the forward transport along the injection direction is stopped before full penetration of the magnetopause. Moreover, the jet is pushed back and simultaneously deflected in the perpendicular plane to the magnetic field. Our simulations evidence physical processes advocated previously by the theoretical model of impulsive penetration and revealed in laboratory experiments.

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Laboratory Experiments

Koepke¹

2021

Magnetospheres in the Solar System

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The role of high frequency oscillations in the penetration of plasma clouds across magnetic boundaries

Cited by 22 publications

References 34 publications

The penetration of plasma clouds across magnetic boundaries: The role of high frequency oscillations

The penetration of plasma clouds across magnetic boundaries: The role of high frequency oscillations

Transport and entry of plasma clouds/jets across transverse magnetic discontinuities: Three‐dimensional electromagnetic particle‐in‐cell simulations

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