Flow dynamics and magnetic induction in the von-Kármán plasma experiment

Plihon, Nicolas; Bousselin, Guillaume; Palermo, F.; Moralès, J.; Bos, Wouter J. T.; Godeferd, Fabien S.; Bourgoin, Mickaël; Pinton, Jean‐François; Moulin, Marc; Aanesland, Ane

doi:10.1017/s002237781400083x

Cited by 18 publications

(21 citation statements)

References 42 publications

(63 reference statements)

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“…In many experiments, two-faced Mach probes or similar devices are used for this purpose. 3,[26][27][28][29] The Mach probe is a two-side planar or cylindrical probe where the IVcurve of each side is measured. In presence of non-zero plasma flux in direction normal to the probe surface, the ion saturation currents are different for the two sides of the probe indicating a non-zero ion drift.…”

Section: Experimental Validation Of a Plasma Flow In Presence Ofmentioning

confidence: 99%

“…[5][6][7][8] For example, a recent von-Karman flowing plasma experiments aims to explore the dynamics of basic induction processes in order to better understanding the magnetic properties of astrophysical bodies (including Earth) and interaction of the solar wind with the Earth's magnetosphere. 3,4 Another interesting example is laser-plasma accelerators recently proposed as the next revolutionary generation of particle accelerators. 1,2 These devices have great prospective in high-energy physics as very compact quasi-monoenergetic sources of relativistic particles.…”

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confidence: 99%

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Plasma acceleration using a radio frequency self-bias effect

Rafalskyi

Aanesland

2015

Physics of Plasmas

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International audienceIn this work plasma acceleration using a RF self-bias effect is experimentally studied. The experiments are conducted using a novel plasma accelerator system, called Neptune, consisting of an inductively coupled plasma source and a RF-biased set of grids. The plasma accelerator can operate in a steady state mode, producing a plasma flow with separately controlled plasma flux and velocity without any magnetic configuration. The operating pressure at the source output is as low as 0.2 mTorr and can further be decreased. The ion and electron flows are investigated by measuring the ion and electron energy distribution functions both space resolved and with different orientations with respect to the flow direction. It is found that the flow of electrons from the source is highly anisotropic and directed along the ion flow and this global flow of accelerated plasma is well localized in the plasma transport chamber. The maximum flux is about 7.5·1015 ions s−1 m−2 (at standard conditions) on the axis and decreasing to almost zero at a radial distances of more than 15 cm from the flow axis. Varying the RF acceleration voltage in the range 20350 V, the plasma flow velocity can be changed between 10 and 35 km/s. The system is prospective for different technology such as space propulsion and surface modification and also interesting for fundamental studies for space-related plasma simulations and investigation of the dynamo effect using accelerated rotating plasmas. I. INTRODUC

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Section: Experimental Validation Of a Plasma Flow In Presence Ofmentioning

confidence: 99%

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confidence: 99%

Plasma acceleration using a radio frequency self-bias effect

Rafalskyi

Aanesland

2015

Physics of Plasmas

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“…1 and described in details in Ref. 15. It consists of a cylindrical magnetized plasma device in which the plasma production is achieved by a 13.56 MHz radio-frequency (RF) power generator (up to 1.4 kW) coupled to a 3-turn antenna through a L-type matching network.…”

Section: A Experimental Setupmentioning

confidence: 99%

How plasma parameters fluctuations influence emissive probe measurements

et al. 2015

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Équipe 107 : Physique des plasmas chaudsInternational audienceRelationship between the floating potential of an emissive probe and plasma potential oscillations is studied in the case of controlled oscillations of plasma parameters. This relationship is compared to a quasi-static model for floating potential oscillations that assumes a constant emission current and includes the fluctuations of plasma parameters (density and electron temperature). Two different plasma regimes are considered. In the first one, the model is coherent with experimental results. In the second, the model does not fulfill one of the assumption due to the evidence of emission current oscillations when the mean emission current exceeds a given threshold. This second regime highlights the importance of taking into account emission current oscillations in the interpretation of emissive probe measurements. Nevertheless, discrepancies are still observed between emissive probe floating potential and plasma potential oscillations

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“…Besides being of astrophysical (origin of observed fields) and fundamental (what happens?) physical interest, it is likely soon to be attacked not just theoretically, but also experimentally, with the advent of laboratory experiments aiming to reproduce the plasma dynamo process (Spence et al 2009;Meinecke et al 2014Meinecke et al , 2015Plihon et al 2015;Forest et al 2015). The first demonstration of this process in a 3D kinetic numerical simulation by Rincon et al (2016) has indeed confirmed the ubiquitous appearance of mirror and firehose fluctuations, although a detailed investigation of the full multiscale problem remains computationally too intensive to be affordable.…”

Section: Introductionmentioning

confidence: 99%

Pressure-anisotropy-driven microturbulence and magnetic-field evolution in shearing, collisionless plasma

Melville¹,

Schekochihin²,

Kunz³

2016

Mon. Not. R. Astron. Soc.

126

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The nonlinear state of a high-beta collisionless plasma is investigated in which an externally imposed linear shear amplifies or diminishes a uniform mean magnetic field, driving pressure anisotropies and, therefore, firehose or mirror instabilities. The evolution of the resulting microscale turbulence is considered when the external shear changes, mimicking the local behaviour of a macroscopic turbulent plasma flow, viz., the shear is either switched off or reversed after one shear time, so that a new macroscale configuration is superimposed on the microscale state left behind by the previous one. It is shown that there is a threshold value of plasma beta: when β ≪ Ω/S (ion cyclotron frequency/shear rate), the emergence of firehose or mirror fluctuations when they are driven unstable by shear and their disappearance when the shear is removed or reversed are quasi-instantaneous compared to the macroscopic (shear) timescale. This is because the free-decay time scale of these fluctuations is ∼ β/Ω ≪ S −1 , a result that arises from the free decay of both types of fluctuations turning out to be constrained by the same marginal-stability thresholds as their growth and saturation in the driven regime. In contrast, when β Ω/S ("ultra-high" beta), the old microscale state can only be removed on the macroscopic (shear) timescale. Furthermore, it is found that in this ultra-high-beta regime, when the firehose fluctuations are driven, they grow secularly to order-unity amplitudes (relative to the mean field), this growth compensating for the decay of the mean field, with pressure anisotropy pinned at marginal stability purely by the increase in the fluctuation energy, with no appreciable scattering of particles (which is unlike what happens at moderate β). When the shear reverses, the shearing away of this firehose turbulence compensates for the increase in the mean field and thus prevents growth of the pressure anisotropy, stopping the system from going mirror-unstable. Therefore, at ultra-high β, the system stays close to the firehose threshold, the mirror instability is almost completely suppressed, while the mean magnitude of the magnetic field barely changes at all. Implications of the properties of both ultra-high-and moderate-beta regimes for the operation of plasma dynamo and thus the origin of cosmic magnetism are discussed, suggesting that collisionless effects are broadly beneficial to fast magnetic-field generation.

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Flow dynamics and magnetic induction in the von-Kármán plasma experiment

Cited by 18 publications

References 42 publications

Plasma acceleration using a radio frequency self-bias effect

Plasma acceleration using a radio frequency self-bias effect

How plasma parameters fluctuations influence emissive probe measurements

Pressure-anisotropy-driven microturbulence and magnetic-field evolution in shearing, collisionless plasma

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