[en] Direct estimation of the electric field in the cathode discharge zones is achieved by optogalvanic spectroscopy. Stark level skies above 12 cm-I have been calculated in Ne and Ar noble gas atoms near the cathode walls in Ne and Ar hollow cathode discharge tubes. Fields of the order of 5 kV/cm are estimated

[en] Heat flux in weakly magnetized collisionless plasma is, according to theoretical predictions, limited by whistler turbulence that is generated by heat flux instabilities near threshold. Observations of solar wind electrons by Gary and coworkers appear to confirm the limit on heat flux as being roughly the product of the magnetic energy density and the electron thermal velocity, in agreement with prediction (Pistinner and Eichler 1998)

[en] LAMAS-IOM TOF-MS that was recently designed for inorganic quantitative analysis is also well suitable for investigation of laser irradiation interaction with solids. This feature allows one to analyze plasma on early stage and gives an excellent possibility to complete existent physical model. This work is dedicated to investigation of yield doubly charged ions for different elements

[en] This work is about research conditions of methane conversion to molecular hydrogen. The experimental set-up includes annular nozzle as a gas source, electron gun with plasma cathode that generates electron beam, flow reactor (length = 330 mm, i.d. = 28 mm). Probe is picked as a neutral molecular beam by earthed skimmer (d = 3 mm) from the end of reactor. Then the molecular beam reaches monopole mass-spectrometer where ionization occurs

[en] The 2002 annual conference of the Israeli Plasma and Science Association was held on the 5 March 2002. The book of abstracts contains over 30 abstracts on various aspect of the plasma science

[en] It is well known that electromagnetic radiation with a frequency equal to the cyclotron frequency of plasma electrons is strongly absorbed by magnetized plasma. It is shown here that this absorption does not occur in the presence of a second, properly de tuned, electromagnetic pump pulse. The plasma can thus be made transparent at the cyclotron frequency. The pump is de tuned from the probe by the plasma frequency. Transparency occurs because the currents induced at the cyclotron frequency by sideband of the pump can cancel the currents induced by the probe. This effect is very similar to electromagnetically-induced transparency of atomic vapors. The essential difference is that the plasma considered here is completely classical, and no quantum mechanical effects are invoked to produce the electromagnetically-induced transparency. The plasma system is significantly more complex than the three level quantum system in particular, a non-local interaction, the plasma oscillation, corresponds to one of the levels. Potential applications of the electromagnetically-induced transparency in plasma will be discussed

[en] Generation of dense long scale axisymmetrical plasmas is important for the study of physics of inertial confinement fusion driven by high-intensity laser and ion beams. Another area of interest is a soft 9(-ray laser, which require long plasma medium with electron densities in range 1019 - 1020 cm-3. Such plasmas can be created by a slow capillary discharge with evaporated wall and current period T >> I/v, where I is the length of the capillary, and v is the velocity of the plasma jet blown out from the capillary. Using such discharges, stable dense plasma at temperatures of 1-3 eV has been obtained [1-3]. Typical lifetime of such discharges is higher than one microsecond. Much faster and powerful capillary discharges (T = 10-100 ns) produced plasma densities in range of 1018 - 1020 cm-3 and higher temperatures on the order of tens of eV [4]. However, intensity of the radiation emitted by such plasma exhibits strong shot-to-shot variation [5, 6], and the conclusion that the plasma inside the channel was homogenous is not evident

[en] The Hall instability of a perfectly conducting plasma is studied. The two-dimensional magnetohydrodynamic equations for systems with large Larmor radius for a two-fluid model, in which the Hall term is taken into account in Faraday's law, are investigated. The flow regimes and the plasma parameters where the magnetic field penetrates into plasma are investigated. By using a linearized theory it is shown, that the plasma may become unstable under small perturbations propagating in some directions. The most unstable perturbations propagate in the direction where the wave vector is orthogonal to the magnetic field. In that respect, the Hall instability looks like the Rayleigh-Taylor instability. However, unlike the latter, the Hall instability is compressional and may lead to the density clumping instead of rippling. The growth rate for short-wavelengths Hall instability is obtained by using the frozen-coefficients approach. The non-evolutionarity (i.e. the ill-posedness of the initial-value problem) first mentioned by Brushlinskii and Morozov in their numerical studies of flows in Hall plasma accelerators is analyzed. The dependence of the Hall instability on the steady-state plasma parameters of the plasma flow in the channel, and the conditions for existence of the Hall instability are discussed in detail. It is shown that the condition for Hall instability may be satisfied for typical values achieved in various plasma flows such as plasma accelerators and magnetohydrodynamic generators and some problems related to fusion reaction, geophysics, astrophysics, etc

[en] The study of non-equilibrium current carrying plasmas is important for the understanding of basic phenomena in laboratory plasmas, astrophysics, and various other applications. A fundamental question underlying the various attempts to describe a current carried through the plasma concerns the formation of non-neutral regions and generation of strong electric fields. Theories and numerical simulations, predicting the development of these regions with turbulent and quasi-DC electric fields in pulsed plasmas, use assumptions that limit the validity of such theories for experimental systems. We investigate experimentally the phenomenon of electric field generation, to determine characteristics and the spatial distribution of these fields, to study the formation of non-neutral regions, the acceleration of charged particles and generation of instabilities. This study is performed in a Plasma Opening Switch configuration. Non-intrusive spectroscopic methods, including Laser Induced Fluorescence and plasma doping methods, are implemented to achieve high temporal, spectral, and spatial resolutions simultaneously

[en] Uniform, m-fold symmetric, rotating vortex patches (V-states) in 2D ideal fluids were discovered by Deem and Zabusky two decades ago [1]. Analogous structures can be formed in pure electron plasmas trapped in Penning-Malmberg traps [2], where plasma density plays the role of vorticity. Here we consider excitation and control of nonuniform V-states in non neutral plasmas, the problem related to recent studies of inviscid vorticity symmetrization of 2D vortices [3]. It will be shown that a family of stable, nonuniform, m-fold symmetric, non neutral plasma structures in two dimensions (nonuniform V-states) can emerge by subjecting an axisymmetric plasma with a sharp density edge profile to a weak oscillating external potential of appropriate symmetry. The phenomenon is due to nonlinear synchronization (autoresonance) in the system, as the plasma density distribution self-adjusts to equate the rotation frequency of the plasma structure with slowly varying oscillation frequency of the external perturbation. The synchronization is induced by passage through resonance with the isolated eigenfrequency of the linearized problem, provided the driving potential amplitude exceeds a threshold. We shall present a quasilinear theory of excitation of nonuniform V-States by synchronization and compare the predictions of this theory with contour dynamics simulations