| 1. |
- Beckers, J., et al.
(författare)
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Physics and applications of dusty plasmas : The Perspectives 2023
- 2023
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Ingår i: Physics of Plasmas. - : AIP Publishing. - 1070-664X .- 1089-7674. ; 30:12
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Tidskriftsartikel (refereegranskat)abstract
- Dusty plasmas are electrically quasi-neutral media that, along with electrons, ions, neutral gas, radiation, and electric and/or magnetic fields, also contain solid or liquid particles with sizes ranging from a few nanometers to a few micrometers. These media can be found in many natural environments as well as in various laboratory setups and industrial applications. As a separate branch of plasma physics, the field of dusty plasma physics was born in the beginning of 1990s at the intersection of the interests of the communities investigating astrophysical and technological plasmas. An additional boost to the development of the field was given by the discovery of plasma crystals leading to a series of microgravity experiments of which the purpose was to investigate generic phenomena in condensed matter physics using strongly coupled complex (dusty) plasmas as model systems. Finally, the field has gained an increasing amount of attention due to its inevitable connection to the development of novel applications ranging from the synthesis of functional nanoparticles to nuclear fusion and from particle sensing and diagnostics to nano-contamination control. The purpose of the present perspectives paper is to identify promising new developments and research directions for the field. As such, dusty plasmas are considered in their entire variety: from classical low-pressure noble-gas dusty discharges to atmospheric pressure plasmas with aerosols and from rarefied astrophysical plasmas to dense plasmas in nuclear fusion devices. Both fundamental and application aspects are covered.
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| 2. |
- Ratynskaia, Svetlana V., et al.
(författare)
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Electrostatic interaction between dust particles in weakly ionized complex plasmas
- 2006
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Ingår i: Physics of Plasmas. - : AIP Publishing. - 1070-664X .- 1089-7674. ; 13:10
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Tidskriftsartikel (refereegranskat)abstract
- The electrostatic potential around a dust particle in a complex plasma is calculated, taking into account ion-neutral collisions and collective effects, in a range of plasma parameters relevant for typical laboratory experiments. The existence of attractive wells and dependence of their shape on the main experimental control parameters, neutral gas pressure, and dust number density, is investigated.
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| 3. |
- Ratynskaia, Svetlana V., et al.
(författare)
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Probe measurements of low-frequency plasma potential and electric field fluctuations in a magnetized plasma
- 2002
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Ingår i: Physics of Plasmas. - : AIP Publishing. - 1070-664X .- 1089-7674. ; 9:10, s. 4135-4143
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Tidskriftsartikel (refereegranskat)abstract
- A system of two cylindrical probes aligned along the magnetic field, and equipped with insulating end plugs, is proposed for measurement of low-frequency fluctuations of the electrostatic field in a magnetized plasma. It is demonstrated by modeling and experiments that the plug probe floats close to the plasma potential. The electric field component in a given direction is obtained by subtracting the plasma potentials obtained on two spatially separated plug probes. The probe system is applied to low-frequency electrostatic fluctuations in a simple magnetized torus, and reveals the presence of global oscillations, large scale propagating structures (m=1 modes), and developed turbulence with power-law spectra. Two different mode branches for the fluctuations are identified by comparing results from plug probes with results from conventional probes. Sources of errors arising from applying floating potential of conventional probes for electric field measurements are pointed out and discussed.
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| 4. |
- Ratynskaia, Svetlana V., et al.
(författare)
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Statistics of particle transport in a two-dimensional dusty plasma cluster
- 2005
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Ingår i: Physics of Plasmas. - : AIP Publishing. - 1070-664X .- 1089-7674. ; 12:2
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Tidskriftsartikel (refereegranskat)abstract
- Statistical analysis is performed on long time series of dust particle trajectories in a two-dimensional dusty plasma cluster. Particle transport is found to be superdiffusive on all time scales until the range of particle displacements approaches the size of the cluster. Analysis of probability distribution functions and rescaled range analysis of the position increments show that the signal is non-Gaussian self-similar with Hurst exponent H=0.6, indicating that the superdiffusion is caused by long-range dependencies in the system. Investigation of temporal and spatial characteristics of persistent particle slips demonstrates that they are associated with collective events present on all time scales and responsible for the non-Gaussianity and long-memory effects.
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| 5. |
- Ratynskaia, Svetlana V., et al.
(författare)
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Transport in strongly coupled two-dimensional complex plasmas : Role of the interaction potential
- 2007
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Ingår i: Physics of Plasmas. - : AIP Publishing. - 1070-664X .- 1089-7674. ; 14:1
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Tidskriftsartikel (refereegranskat)abstract
- Observations of particle motion in a complex plasma monolayer in rf discharge have revealed anomalous dependence on neutral gas pressure; an immobile system at high gas pressures, then, decreasing the pressure, a state with viscoelastic vortical fluid motions and, hence, dramatically enhanced transport, followed again by an ordered state. While the inhibited transport at higher pressures can be attributed to dissipation on neutrals, the transition of the system back to an ordered state at lower pressures has been explained by an increase of the dust-dust viscous dissipation due to significant modifications of the interaction potential between the particles.
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| 6. |
- Rypdal, K., et al.
(författare)
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Fluctuation threshold and profile resilience in weakly ionized plasma in a curved, unsheared magnetic field
- 2004
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Ingår i: Physics of Plasmas. - : AIP Publishing. - 1070-664X .- 1089-7674. ; 11:10, s. 4623-4633
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Tidskriftsartikel (refereegranskat)abstract
- A study of electrostatic fluctuations in a weakly ionized plasma confined by a purely toroidal magnetic field B is presented. At low B field the plasma is quiescent and transport is provided by stationary ExB flows along open equipotential surfaces. For B above a certain threshold, strong electrostatic fluctuations are excited, and the electron pressure profile on the low-field side is resilient with scale length much shorter than the threshold scale length for flute instability. At threshold the fluctuations exhibit the signatures of a monochromatic drift mode, and above threshold they are dominated by flute modes growing on the low-field side. Threshold behavior and profile resilience are explained as a two-stage process, where drift waves act as a seed for the unstable flute modes, and where a negative feedback mechanism involving anomalous transport regulates the electron pressure profile to maintain the imposed particle flux.
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| 7. |
- Rypdal, K., et al.
(författare)
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Statistics of low-frequency plasma fluctuations in a simple magnetized torus
- 2003
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Ingår i: Physics of Plasmas. - : AIP Publishing. - 1070-664X .- 1089-7674. ; 10:7, s. 2686-2695
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Tidskriftsartikel (refereegranskat)abstract
- Statistical analysis is performed on time series of plasma potential and electron pressure fluctuations for two particular plasma states in a simple magnetized torus. In spite of the occurrence of cyclic trends in the signals, the analysis demonstrates the existence of long-range dependence on much longer time-scales than the plasma confinement time, and both Gaussian and non-Gaussian self-affinity is demonstrated in the probability distribution functions (PDFs) of increasingly coarse grained time series. Non-Gaussian PDFs for electron pressure fluctuations p are believed to arise from a nonlinear relationship between p and the plasma potential V. Non-Gaussian PDFs for V are well approximated by distributions derived from extreme value statistics.
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| 8. |
- Strauss, H., et al.
(författare)
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Comparison of JETAVDE disruption data with M3D simulations and implications for ITER
- 2017
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Ingår i: Physics of Plasmas. - : AIP Publishing. - 1070-664X .- 1089-7674. ; 24:10
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Tidskriftsartikel (refereegranskat)abstract
- Nonlinear 3D MHD asymmetric vertical displacement disruption simulations have been performed using JET equilibrium reconstruction initial data. Several experimentally measured quantities are compared with the simulation. These include vertical displacement, halo current, toroidal current asymmetry, and toroidal rotation. The experimental data and the simulations are in reasonable agreement. Also compared was the correlation of the toroidal current asymmetry and the vertical displacement asymmetry. The Noll relation between asymmetric wall force and vertical current moment is verified in the simulations. Also verified is the toroidal flux asymmetry. Although in many ways, JET is a good predictor of ITER disruption behavior, JET and ITER can be in different parameter regimes, and extrapolating from JET data can overestimate the ITER wall force.
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| 9. |
- Vignitchouk, Ladislas, et al.
(författare)
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Electron reflection effects on particle and heat fluxes to positively charged dust subject to strong electron emission
- 2018
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Ingår i: Physics of Plasmas. - : AMER INST PHYSICS. - 1070-664X .- 1089-7674. ; 25:6
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Tidskriftsartikel (refereegranskat)abstract
- A new model describing dust charging and heating in unmagnetized plasmas in the presence of large electron emission currents is presented. By accounting for the formation of a potential well due to trapped emitted electrons when the dust is positively charged, this model extends the so-called OML+ approach, thus far limited to thermionic emission, by including electron-induced emission processes, and in particular low-energy quasi-elastic electron reflection. Revised semi-analytical formulas for the current and heat fluxes associated with emitted electrons are successfully validated against particle-in-cell simulations and predict an overall reduction of dust heating by up to a factor of 2. When applied to tungsten dust heating in divertor-like plasmas, the new model predicts that the dust lifetime increases by up to 80%, as compared with standard orbital-motion-limited estimates.
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| 10. |
- Yaroshenko, V., et al.
(författare)
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Determination of the ion-drag force in a complex plasma
- 2005
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Ingår i: Physics of Plasmas. - : AIP Publishing. - 1070-664X .- 1089-7674. ; 12:9
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Tidskriftsartikel (refereegranskat)abstract
- The ion-drag force acting on dust particles in the positive column of a dc discharge is measured in the pressure range of 20-120 Pa. The force is obtained by a method which does not require a priori knowledge of the particle charge, but uses the charge gradient determined from the same experiment. The method depends only on two experimentally determined quantities: the particle drift velocity and the electric field. The comparison of experimental results with theoretical models is presented and discussed.
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