Alushta-2012 International Conference-School on Plasma Physics and Controlled Fusion and The Adjoint Workshop
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- I-15 FABRICATION OF NANOPOWDERS IN RF PLASMAS: DIAGNOSTICS AND MODELLING
- Literature  Winter, J., 2004, Plasma Phys. Contr. Fusion, 46, B583  Kovačević, E., Stefanović, I., Berndt, J., Pendleton Y.J., Winter, J. 2005, ApJ, 620
- I-18 . KINETIC DESCRIPTION OF DUSTY PLASMAS AND EFFECTIVE GRAIN POTENTIALS
V.А. Zhovtyansky, Yu. I. Lelyukh, Ya.V. Tkachenko
The Gas Institute, National Academy of Sciences of Ukraine
39, Degtyarivs‟ka St., 03113 Kyiv, Ukraine
The transport processes are the reason of deviations of the plasma state from local
thermodynamic equilibrium (LTE). This effect is no exception in electric arc plasma contrary
to the widespread opinion. It takes place if even plasma is so dense, that complies with
Griem‟s LTE criterion. The reason is the radiation transfer at the condition of the radial
gradient of temperature in cylindrical plasma as well as longitudinal gradient in the two-
dimensional model of the arc. It was shown by one of the authors with the employees in early
experimental studies. The effect mentioned was accomplished due to using of specially
designed tomographic spectrometer. This spectrometer provided practically simultaneous
recording of the spectral line shapes in various space elements of plasma as well as the space
distribution of the spectral line emission and absorption. As was shown, the radiation from the
hot arc core is able to overpopulate the resonance level of plasma forming atoms at the arc
periphery, where temperature is relatively small. This non-LTE has a qualitatively another
character as compared with the widely known non-equilibrium in plasma of low current
discharges, where the radiation leaves freely the volume of plasma and as a result the
resonance state of atoms is found to be under-populated as well as the density of electrons.
Resonance spectral transition is determining factor to plasma be in LTE. This leads to
the spread of so-called two-level model of atom with two energy levels – the ground 1 and
excited 2. The basic equation for the kinetics of the population n
of the exited level of atom
in plasma with account of the processes of radiation transfer excitation is:
– probability of spontaneous radiating transition 2 → 1, n
– the population of
ground level. Here the integral term takes into account the radiative transfer energy. The
is the probability that photon emitted from the arbitrary point r‟, is absorbed
in the volume of coordinate r. In the final version it includes integration to take into account
the self-absorption along each beam:
is normalized per unit distribution of the frequencies of photons, emitted from upper
level of spectral transition, k
– spectral absorption coefficient. Here, the exponent contains
planimetric integral along the line connecting the points with coordinates r and r´.
The system of equations (1), (2) was extended to three-level model of the atom
including the ground, metastable and resonant levels in the quasistatic approximation with the
account of the splitting also of resonance and metastable levels. It was added with equations
of Saha-Boltzmann, Dalton, quasineutrality and Elenbaas-Heller for the heat conductivity.
The solution of this problem illustrate clearly the above effect of growth of the
resonance level population of the plasma forming atom cased by the transport of resonance
radiation as well as the density of electrons on the arc periphery
DUST ION-ACOUSTIC NONLINEAR WAVE STRUCTURES UNDER CONDITIONS
OF NEAR-EARTH AND LABORATORY PLASMAS
Institute for Dynamics of Geospheres RAS, Moscow, Russia
A review on dust ion-acoustic nonlinear wave structures in dusty plasmas is presented. The
basic experiments on the nonlinear wave structures in dusty plasmas are described and the
corresponding theoretical descriptions are given. A possibility of the existence of the dust ion-
acoustic nonlinear structures under near-Earth conditions is discussed.
For the description of formation and evolution of dust ion-acoustic shocks and solitons
the so-called ionization source model is forwarded. This model allows us to describe all the
features of the laboratory experiments on dust ion-acoustic shocks performed at the Institute
of Space and Astronautical Science (Japan) and at the University of Iowa (USA): the
suppression by dust of charge separation in the front of shock; the width of the shock front;
the dependence of the shock speed on dust density; the fact that shocks are excited for rather
large dust densities. The most important dissipative processes, which are responsible for the
generation of dust ion-acoustic shocks and influence dust ion-acoustic soliton dynamics, are
investigated. Among them are the anomalous dissipation due to dust charging process;
absorption and scattering of ions by dust grains; as well as the kinetic (including Landau)
damping. A possibility of observation of shocks related to the dust charging process in active
rocket experiments, which involve the release of some gaseous substance in near-Earth space,
is shown. As an example of dust ion-acoustic shocks in nature, we consider the bow shock
formed in the interaction of the solar wind with cometary dusty coma.
The dynamics of dust ion-acoustic solitons is analyzed in a wide range of dusty plasma
parameters. The cases of both a positive dust grain charge arising due to the photoelectric
effect caused by intense electromagnetic radiation and a negative grain charge established in
the absence of electromagnetic radiation are considered. It is shown that, in dusty plasma with
negatively charged dust grains, both compression and rarefaction solitons can propagate,
whereas in plasma with positively charged dust grains, only compression solitons can exist.
The amplitudes of soliton-like compression and rarefaction perturbations decrease in the
course of their evolution and their velocities (the Mach numbers) decrease monotonically in
time. We demonstrate that, after the interaction between any types of soliton-like
perturbations, their velocities and shapes are restored (with a certain phase shift) to those of
the corresponding perturbations propagating without interaction; i.e., they are in fact weakly
We investigate a possibility of experimental observation of the dust ion-acoustic
solitons and discuss a possibility of formation of the shock wave-like structures during the
soliton evolution. It is shown that the nonlinear dust ion-acoustic structures may find
significant technological applications in, e.g., the so-called hypersonic aerodynamics.
This work is supported by the Presidium of the Russian Academy of Sciences (the
basic research program No. 22 “Fundamental problems of research and exploration of the
Solar system”), the Division of Earth Sciences of the Russian Academy of Sciences (the basic
research program No. 5 “Nanoscale particles: conditions of formation, methods of analysis
and recovery from mineral raw”), and the Russian Foundation for Basic Research (grant No.
FABRICATION OF NANOPOWDERS IN RF PLASMAS: DIAGNOSTICS AND
, Brankica Sikimić
, Igor Denysenko
and Jorg Winter
Experimental Physics II and Research Department "Plasmas with Complex Interactions",
Ruhr Universitdt Bochum, GERMANY
School of Physics and Technology, V. N. Karazin Kharkiv National University, Kharkiv,
The formation of hydrocarbon nanopowders in RF low pressure plasma and their influence on
relevant plasma properties is reviewed. Despite of 20 years of research in the field, it is still
important to develop an in depth understanding of the basic physical and chemical processes
that lead to the formation of nanoparticles. It has been shown that by controlling the discharge
parameters, such as the discharge pulsing frequency, it is possible to enhance or suppress the
nucleation of protoparticles for nanoparticle formation and growth. Besides that, by
modulating the RF power with low frequency signal (100 Hz - 1 kHz) and by tracing the
dynamics of reactive species in the plasma afterglow, some basic properties of discharge can
be understood. The experimental results have been compared with the simple hydrodynamic
model of RF pulsed plasma with argon and argon/nanoparticle mixtures . Between the
model and experimental results there is a good quantitative agreement of electron and Ar
argon metastable (1s
state) dynamics in the pure argon afterglow plasma. The model stresses
the importance of the mean electron energy losses to the walls for the description of the
electron density decay. However, in the presence of dust there is qualitative agreement, but
the calculated Ar
are three times smaller than the measured ones.
The application of electric probes in reactive plasmas is limited due to thin film formation that
changes the probe characteristics. In the plasmas with immersed nanoparticles, the problem is
even larger since the nanoparticle distribution in the probe vicinity changes and so does the
electron and ion density. A planar RF probe has been developed for electron density
measurements in plasmas with film deposition following . However, the distortion of
nanoparticle distribution by the presence of the probe cannot be avoided. We developed a
non-intrusive diagnostics of ion densities and fluxes in reactive plasmas with nanoparticles
that is based on measurements of the electrode bias voltage in the plasma afterglow.
The measurements of absolute electron and Ar
metastable densities and their
dynamics in the plasma afterglow will be presented and compared with the results of the
model. Further, the measurements of ion densities based on the proposed diagnostics will be
presented for pure argon and argon/nanoparticle mixtures. The ion densities will be compared
with independently measured electron densities and the dependence on different discharge
conditions will be discussed.
This work has been supported by DFG Project WI 1700/3-1, Research Department «Plasmas
with Complex Interactions)) of Ruhr Universitat Bochum, Humboldt Foundation and the State
Fund for Fundamental Researches of Ukraine.
 I. Denysenko, I. Stefanovic, B. Sikimic, J. Winter, N. A. Azarenkov and N. Sadeghi J.
2011 J. Phys. D: Appl. Phys. 44 205204
 N. St. J. Braithwaite, J. P. Booth and G. Cunge, 1996 Plasma Sources Sci. Technol. 5 677
THE FORMATION OF NANOPARTICLES AND NANOCOMPOSITES IN
J. Berndt, E.Kovacevic, L.Boufendi
GREMI Université d‟Orléans, France
The formation of particles in plasmas is of high interest for different areas of physics and
technology. Nano – or dust particles have been observed in several different surroundings as
for example in fusion devices , in the interstellar medium  or in prosessing plasmas used
for the deposition of thin films  or the manufacturing of microelectronic devices .
This contribution will focus on the formation of nanoparticles in low temperature and low
pressure plasmas as they are used for example for the production of polymer coatings or the
fabrication of solar cells.
The formation and subsequent growth of nanoparticles in reactive plasmas is a rather complex
process. It involves are large variety of chemical and physical reactions, different time scales
and may have in addition a severe impact on the plasma itself. The whole process can be
roughly divided into three separate phases. The basis for the formation of particles in the
plasma volume are gas phase reactions which are leading to the formation of nanometer sized
clusters or protoparticles. This so called nucleation phase is often followed by the coagulation
phase which characterized by a strong increase of cluster- cluster collisions which results in
the formation of particles with sizes up to some ten nanometers. Once the particles have
reached such a size they become immediately negatively charged and the further growth of
the particles occurs mainly through the sticking of neutral radicals and positive ions from the
gas phase. Each of these phases (nucleation, coagulation and surface growth phase) is
dominated by different charged and uncharged species (neutral radicals, positive and negative
ions) and is governed by different time scales which can range from milliseconds to several
minutes or even hours.
This contribution will mainly deal with the growth of nanoparticles in capacitively coupled
discharges which are operated either with silane or with different hydrocarbon precursors
such as CH
or MMA. A special focus is put on pulsed discharges and on the question
how the pulse frequency influences the different growth phases.
The production of nanocomposite materials with adjustable wetting characteristics will be
discussed as an important example for the application of pulsed nanoparticle forming
 Winter, J., 2004, Plasma Phys. Contr. Fusion, 46, B583
 Kovačević, E., Stefanović, I., Berndt, J., Pendleton Y.J., & Winter, J. 2005, ApJ, 620,
 Kersten H., Deutsch, H., Stoffels,E., Stoffels, W.W., Kroesen, G.M.W., Hippler,R., 2001,
Contrib.Plasma Phys. 41, 598
 Selwyn, G. S., Singh, J. & Bennet, R. S. 1989, J. Vac. Sci. Technol. A 7, 2758
ON THE USE OF DUST PARTICLES AS MICRO-PROBES IN PROCESS PLASMAS
Institute for Experimental and Applied Physics, University of Kiel, Germany
Complex (dusty) plasmas, which can form plasma or Coulomb crystals (see Fig.1) are at
recent a topical research subject in plasma physics . The complexity of dusty plasmas
results in complicated interactions at different scales in energy, space, time and mass.
Experimental and theoretical studies initiated the idea of using externally injected small
particles, which are negatively charged and affected by several forces in plasma, as micro-
probes. From the behavior of the particles in the surrounding plasma local electric fields can
be determined ('particles as electrostatic probes') . Moreover, momentum fluxes in
energetic ion beams ('particles as force probes')  as well as energy fluxes towards the
particles ('particles as thermal probes')  are worth studying.
Fig.1: A two-dimensional cloud of mono-disperse dust micro-particles (10^m) is trapped in a
plasma sheath in front of the adaptive electrode in an rf-plasma. The electrode is segmented,
allowing for manipulation of the trapped micro-particles in real time.
 G.E. Morfill, H. Kersten, Focus issue on complex (dusty) plasmas, New J.Phys. 5(2003),1.
 G. Schubert, R. Basner, H. Kersten, H. Fehske, Eur. Phys. J. D 63(2011), 431.
 T. Trottenberg, V. Schneider, H. Kersten,, Phys. Plasmas 17(2010), 103702.
 H. Maurer, R. Basner, H. Kersten, Rev. Sci. Instrum. 79(2008), 093508.
KINETIC DESCRIPTION OF DUSTY PLASMAS AND EFFECTIVE GRAIN
Bogolyubov Institute for Theoretical Physics 14-b, Metrolohichna Str. 03680 Kiev, Ukraine
The basic points of the consistent kinetic theory of dusty plasmas are formulated. The
equations for microscopic phase densities of plasma particles and grains are derived with
regard to electron and ion absorption by grains and the relevant kinetic equations are found.
Obtained equations are used for kinetic description of effective grain-grain potentials.
Approximate analytical expressions for such potentials are derived and compared with the
results of numerical solutions of the appropriate kinetic equations. The comparison shows
satisfactory agreement between the analytical and numerical results.
The effective grain potentials in the wide range of plasma parameters (from the collisionless
regime to drift-diffusive approximation) are studied numerically in detail. It is shown that
charging processes strongly influences the effective interactions between the grains, in
particular, due to electron and ion absorption by grains the Coulomd-like long-range
behaviour of the effective potentials appears. The influence of the external magnetic on the
asymptotic properties of the potential is also discussed. Obtained numerical solutions make
it possible to study the dependence of stationary grain charge as well as charging currents on
plasma parameters and grain size.
The screening of the moving grain is studied as well. It is shown that due to specific
polarization of plasma the dynamical friction force acting on the particle under consideration
can change its sign and thus to cause particle acceleration provided that the polarization force
exceeds the friction force associated with neutrals. This effect was predicted using analytical
estimates, but now it is confirmed on the basis of numerical solutions.
CHARACTERISTICS OF ENERGETIC-PARTICLE DRIVEN GAM IN THE LARGE
T. Ido, A. Shimizu, M. Osakabe, M. Nishiura, K.Toi, M.Nakamura*, R. Makino*,
Y. Yoshimura, K. Itoh, S. Satake, S. Kato, and LHD experiment group
National Institute for Fusion Science, Oroshi,Toki, Gifu 509-5292, Japan Dept. of Energy
Engineering and Science, Nagoya Univ., Nagoya 464-8603, Japan
Geodesic acoustic mode(GAM) is a branch of zonal flow in toroidal plasmas, and
attracts much attention in the area of turbulent-transport study because the zonal flow is
considered to regulate turbulence. It is driven by not only turbulence but also energetic
particles which will be major players in future nuclear fusion reactors.
In recent LHD experiments, electrostatic potential fluctuation, density fluctuation and
magnetic field fluctuation associated with GAMs are observed by toroidal Mirnov-coil array,
reflectometry, a heavy ion beam probe (HIBP). The GAMs are not observed in plasmas
without high-energy tangential neutral beam injection(NBI). Thus, it is concluded that the
GAM is driven by the injected energetic particles.
The frequency of the energetic-particle driven GAM changes upward with the time scale
of several milliseconds. The initial frequency is roughly proportional to the square-root of
electron temperature. The direct measurement of the potential fluctuation and density
fluctuation by HIBP revealed that spatial structures of the mode with the upward shifted
frequency are consistent with the theoretical prediction of GAMs: m = 0 for the potential
fluctuation and m=1 for the density fluctuation, where m is the poloidal mode number, even
during the frequency change.
The potential fluctuation measured by the HIBP is roughly proportional to the magnetic
field fluctuation measured by a Mirnov coil on the vacuum vessel, and the relation seems to
agree with a theoretical prediction. The amplitude of the potential fluctuation of the GAM
reaches a few kilovolts, and the electrostatic potential energy is comparable to the electron
temperature. The possibility of energy transfer from energetic particles to bulk ions via the
GAM with such large potential fluctuation will be also discussed in the presentation.
 K.Toi, et al, Phys. Rev. Lett., 105, 145003 (2010)
 T.Ido, et al., Nucl. Fusion,51, 073046 (2011)
 D.Zhou, et al., Phys. Plasma, 14, 104502 (2007)
 M. Sasaki, et al., Plasma Phys. Control. Fusion 53, 085017 (2011)
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