Dusty plasmas: synthesis, structure and dynamics of a dust cloud in a plasma (original) (raw)
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Pure and Applied Chemistry, 2000
Formation of dust particles is a common mechanism in low-pressure plasmas. These big particles (in comparison with other plasma species) are sometimes the desired final products of the process, but they may also constitute a severe drawback in certain contexts. In either situation, it is necessary to understand growth mechanisms well, in order to control or avoid dust particle formation. One of the problems that has to be overcome is that dust particle growth is usually a continuous mechanism: once started, it can enter into a cyclic regime where new generations of dust particles are succeeding one after the other. This cyclic phenomenon often induces a side effect consisting of instabilities of a few tens of Hz. This paper discusses the main characteristics of dust successive generations, and particularly the importance of dust-free spaces (void) involved in this process. Finally, some aspects related to deposition when several generations coexist will be presented. Fig. 4 Spectrogram of Fig. 3 around the second and third dust particle generations. It underlines that an oscillating pattern of a few tens of Hz is superimposed on the continuous signal variation. Two alternating regimes can be identified, HOR and LOR. M. MIKIKIAN et al.
Springer Series in Plasma Science and Technology, 2020
Dust is ubiquitous in magnetic fusion devices. It comes either from plasma-induced erosion of the plasma-facing components or, in some cases, dust (powder, aerosol) is deliberately injected into edge plasma for some diagnostic or control purposes. The key processes controlling dust dynamics in the edge plasma differ significantly from those important in "thin", low-temperature plasma in the so-called "dusty plasma" experiments. The main features of dust dynamics in fusion plasmas, including charging, forces, and ablation processes, are considered in this chapter.
5 Dusty plasmas and applications in space and industry
A dusty plasma is an ionized gas containing dust particles, with sizes ranging from tens of nanometers to hundreds of microns. The interaction of the dust particles with the plasma and ambient environment results in a charging of the dust grains. This Chapter summarizes our basic knowledge of dusty plasmas with applications in space, industry and the laboratory. The Introduction (Section 1) provides several examples of dusty plasmas, taken from astrophysics, the solar system, earth, industry and the laboratory. The basic physical principles governing the charging mechanisms and behavior of dust particles is presented in Section 2. Section 3 discusses examples of dusty plasmas in the solar system and earth. Section 4 describes examples of dusty plasmas in industry, and in particular the problem of dust formation and resulting contamination in plasma processing devices used to produce semiconductor devices. Technologically exciting new applications of dusty plasmas are also discussed. Section 5 reviews the basic laboratory devices that have been developed to study dusty plasmas. Some of the most interesting discoveries made in these devices, such as the formation of dust lattice structures (Coulomb crystals) are also described. A brief review of the results of novel experiments in dusty plasmas performed in the microgravity environment onboard the International Space Station (ISS) is presented. Finally, the problem of dust in fusion devices is outlined.
Nuclear Fusion, 2001
The formation and release of particle agglomerates, i.e. debris and dusty objects, from plasma facing components and the impact of such materials on plasma operation in controlled fusion devices has been studied in the Extrap T2 reversed field pinch and the TEXTOR tokamak. Several plasma diagnostic techniques, camera observations and surface analysis methods were applied for in situ and ex situ investigation. The results are discussed in terms of processes that are decisive for dust transfer: localized power deposition connected with wall locked modes causing emission of carbon granules, brittle destruction of graphite and detachment of thick flaking co-deposited layers. The consequences for large next step devices are also addressed.
Disappearance and Reappearance of Dust Particles in Cogenerated Dusty Plasma
IOSR Journal of Applied Physics, 2017
In this unique experiment, where dust is produced in a sub-atmospheric pressure plasma formed between two parallel plate electrodes using a bipolar pulsed dc power supply as the source of power for plasma production, dust disappearance for few seconds is experimented. The plasma forming gas is a mixture of argon and acetylene. The plasma phase chemical reactions help in the formation of sub-micron dust particles that grow in size between two parallel electrodes. Using another single negative pulse, placed in between two electrodes, applied to another electrode, the dust particles can be disappeared for significant duration from the dusty plasma zone. The applied single pulse voltage is varied between 50-250 V. On the application of the pulse, in its initial phase, the dusty plasma gets disturbed and for some duration (~ few seconds) there is no light scattering observed, indicating that the dust is disappeared from the region between the electrodes. Later the plasma formation again reappears and similar structured dusty cloud is formed. The results are important as it gives an idea how to displace some unwanted dusts from our required region to another region.
Formation of plasma dust structures at atmospheric pressure
Journal of Experimental and Theoretical Physics, 2006
The formation of strongly coupled stable dust structures in the plasma produced by an electron beam at atmospheric pressure was detected experimentally. Analytical expressions were derived for the ionization rate of a gas by an electron beam in an axially symmetric geometry by comparing experimental data with Monte Carlo calculations. Self-consistent one-dimensional simulations of the beam plasma were performed in the diffusion drift approximation of charged plasma particle transport with electron diffusion to determine the dust particle levitation conditions. Since almost all of the applied voltage drops on the cathode layer in the Thomson glow regime of a non-self-sustained gas discharge, a distribution of the electric field that grows toward the cathode is produced in it; this field together with the gravity produces a potential well in which the dust particles levitate to form a stable disk-shaped structure. The nonideality parameters of the dust component in the formation region of a highly ordered quasi-crystalline structure calculated using computational data for the dust particle charging problem were found to be higher than the critical value after exceeding which an ensemble of particles with a Yukawa interaction should pass to the crystalline state.
Modeling of dust-particle behavior for different materials in plasmas
Physics of Plasmas, 2007
The behavior of dust particles made of different fusion-related materials ͑Li, Be, B, C, Fe, Mo, or W͒ in tokamak plasmas is simulated using the dust transport code DUSTT ͓A. Pigarov et al., Phys. Plasmas 12, 122508 ͑2005͔͒. The dependencies of the characteristic lifetime of dust particles on plasma parameters are compared for the different dust materials. The dynamics of dust particles in the tokamak edge plasma is studied and the effects of dust material on the acceleration, heating, and evaporation/sublimation of particles are analyzed.
Dusty Plasmas: Elementary Processes, Examples and Possible Applications
This work presents an up-to-date account in dusty plasmas, a new field of current research's interest in applied physics and modern technology. These are complex systems containing nanometer or micrometer-sized particles suspended in plasma. Dust particles may be charged and the plasma and particles behave as plasma, following electromagnetic laws for particle up to about 10 nm or 100 nm if large charges are present. Dusty plasmas are interesting because presence of particles significantly alters the charged particle equilibrium leading to different phenomena. Electrostatic coupling between the grains can vary over a wide range so that the states of the dusty plasma can change from weakly coupled to crystalline. Such plasmas are of interest as a non-Hamiltonian system of interacting particles and as a means to study charging of dust particles in plasmas, electrostatic potential around a dust particle main forces acting on dust particles in plasmas, interaction between dust particles in plasmas, formation and growth of dust particles.
Diagnostics of Particles in RF Dusty Plasma
Ukrainian Journal of Physics, 2022
We study the dynamics of polydisperse dust particles in a rf post-discharge plasma. The levitation of charged particles after the discharge switching-off is found, and the velocities of their fall are measured. A model of the dynamics of particles in the afterglow plasma is proposed to estimate their size and residual charge.