G. Musa

Growth and characteristics of tantalum oxide thin films deposited using thermionic vacuum arc technology

Tantalum pentoxide (Ta2O5) thin films were synthesized using thermionic vacuum arc (TVA) technology. TVA is an original deposition method using a combination of anodic arc and electron gun system for the growth of thin films from solid precursors under vacuum of 10−6 Torr. The properties of the deposited Ta2O5 thin films were investigated in terms of wettability, refractive index, morphology, and structure. The surface free energy was determined by means of surface energy evaluation system indicating a hydrophilic character and the refractive index was measured by Filmetrics F20 device. The morphology was determined from bright field transmission electron microscopy (TEM) image performed by Philips CM 120 ST TEM system. It exhibits nanoparticles of 3–6 nm diameter smoothly distributed. Selected area electron diffraction pattern revealed the contrast fringes given by complex polycrystalline particles included in the amorphous film. The measured fringes could be indexed using monoclinic structure of Ta2O5.

Study of Metal and Ceramic Thermionic Vacuum arc Discharges

The thermionic vacuum arc (TVA) is a new type of plasma source, which generates a pure metal and ceramic vapour plasma containing ions with a directed energy. TVA discharges can be ignited in high vacuum conditions between a heated cathode (electron gun) and an anode (tungsten crucible) containing the material. The accelerated electron beam, incident on the anode, heats the crucible, together with its contents, to a high temperature. After establishing a steady-state density of the evaporating anode material atoms, and when the voltage applied is high enough, a bright discharge is ignited between the electrodes. We generated silver and Al2O3 TVA discharges in order to compare the metal and ceramic TVA discharges. The electrical and optical characteristics of silver and Al2O3 TVA discharges were analysed. The TVA is also a new technique for the deposition of thin films. The film condenses on the sample from the plasma state of the vapour phase of the anode material, generated by a TVA. We deposited silver and Al2O3 thin films onto an aluminium substrate layer-by-layer using their TVA discharges, and produced micro and/or nano-layer Ag-Al2O3 composite samples. The composite samples using scanning electron microscopy was also analysed.

The kinetics of monochromatization of plasma light emission

This paper is concerned with the monochromatization of the visible spectrum of rare gas discharges upon addition of either oxygen, hydrogen or chlorine gas: the M-effect. This phenomenon, observed over 20 years ago at the National Institute for Lasers, Plasma and Radiation Physics (Bucharest), is clearly explained here for the first time. The explanations contain references to all most relevant previous work on this subject. Assuming that the exacerbation of a given emission line results from the collisional interaction between an electropositive gas (the rare gas) and an appropriate electronegative gas, a general method, based on calculation of the energy balance of their excited energy levels, is developed for determining the gas mixtures for which the M-effect can be obtained, along with the corresponding wavelength of the monochromatic emission. These calculations show that the M-effect is highly probable in discharges combining inert gases with oxygen or hydrogen. The experimental results are in perfect agreement with these calculations. The M-effect is an important fundamental effect in physics and has much potential for applications requiring monochromatic light sources for both research and industry.

Investigation of Properties of Boron Thin Film Deposited By Thermionic Vacuum Arc Technology

In this study, we first used boron as anode material in the TVA system. We also present boron thin film deposition using TVA technology.

Emission Spectra of Two Interacting Plasmas

The aim of this present paper is to put in evidence the emission spectral lines of Ar that present M‐effect at the interaction of two different ionized gas flows.

Investigation of the Carbon Produced by Methane Pulsed Discharge

In this paper, we report the new production method amorphous carbon grown on sharpened tungsten electrode at atmospheric pressure by using high voltage pulsed methane discharge.

17th European Conference on Atomic and Molecular Physics of Ionized Gases

The 17th European Conference on Atomic and Molecular Physics of Ionized Gases (ESCAMPIG-17) was held in Constanta, Romania, on 1–5 September 2004. ESCAMPIG is an important biennial European conference at which useful exchanges of ideas and discussion of new achievements in low temperature plasma physics take place. The meeting was held in the ambient location of Constanta, Romania, which provided the perfect location to encourage interaction between the related research communities attending the conference. The local organizers, as well as the plasma scientists of Romania, were all very much honoured that Constanta was selected by the International Scientific Committee as the location for ESCAMPIG-17. The conference was the second largest plasma physics conference ever to take place in Romania, second only to the ICPIG conference of 1969 in Bucharest—a huge conference with four parallel sections and simultaneous translation in four languages (English, German, French and Russian) in all four parallel sections. In contrast, ESCAMPIG-17 maintained the founding ideals and held single sessions only to encourage and strengthen the relationships between research communities. During ESCAMPIG-17 we had the opportunity to attend and hear excellent invited lectures presenting outstanding new results in plasma physics. A selection of those invited lectures from ESCAMPIG-17 is published in this issue of Plasma Sources Science and Technology. We would like to take this opportunity to express our thanks to all the invited lecturers and also to all the participants who attended ESCAMPIG-17. The Local Organizing Committee would particularly like to thank all the International Scientific Committee members. Special thanks are due to Professor Gerrit Kroesen and Professor Nader Sadeghi for their valuable and continuous support in solving our problems, no matter how complicated they were.