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  • Author: László Jakab-Farkas x
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Development of a Pressure Measuring Unit Based on a Thermal Conductivity Gauge and a Low-Cost Embedded Solution for Mid-Range Vacuum Applications

Abstract

This study presents the development of a pressure measuring unit based on a Pirani gauge and a dedicated embedded system, incorporating a simple, low-cost practical solution for significantly reducing the various measurement altering factors, such as drifts, offsets and set point drifts. This is achieved by eliminating the conventional differential analogue signal processing stage and replacing it with a high resolution analog to digital converter. Therefore the goal was to minimize the number of the electronic components whose operation is influenced by variations in ambient temperature. The main topics discussed in the paper include the presentation of the measuring circuit’s configuration, the development of a low-cost embedded system, the calibration method and the solution implemented for eliminating the platforms limitation regarding the precision of the different mathematical calculations.

Open access
Vesicular Arbuscular Mycorrhiza Influences the Histo-Anatomic Characteristics of Vegetative Organs in Artemisia annua

Abstract

Recent studies have shown that vesicular-arbuscular mycorrhizae stimulate plant growth in case of Artemisia annua plants. According to these studies mycorrhization can enhance plant height and biomasses, shoot branching and inter-nodal length, foliar glandular hair density, and nutrient status of shoots and leafs. Contradictory data were obtained in case of leaf chlorophyll content and photosynthetic rate. The effects of vesicular-arbuscular mycorrhizae on roots, shoots and leafs anatomy of A. annua have not been studied yet. The aim of this paper was to compare the microscopic characteristics of the vegetative organs from the Artemisia annua plants treated with vesicular-arbuscular mycorrhizae, with those from the control plants. Rhizophagus irregularis influenced the development of vascular tissues in root and stem of Artemisia plants by increasing their surface in the organs. Mycorrhization also reduced the percentage of lignification in the cortex of the root, increased the percentage of palisade parenchyma in leaf and had a positive effect on foliar glandular hair density. Further investigations are necessary to find out the role of these histo-anatomic alterations in the growth and development of Artemisia plants.

Open access
Multilevel Distributed Embedded System for Control of the DC Magnetron Sputtering Process

Abstract

The paper presents in detail a unique multilevel control architecture designed for the comprehensive management of the DC magnetron sputtering process and of all subsystems of the sputtering equipment. The ultimate goal is to increase the repeatability, stability and the controllability of the complex process. The presented topics include embedded and distributed electronics, data acquisition and supervisory control, networking, data management, redundant local and remote data-archiving. There are presented platform independent algorithms managing the data exchange between computational devices, and conclusions are drawn regarding the efficiency of the various algorithms used.

Open access
Macroscopic Thin Film Deposition Model for the Two-Reactive-Gas Sputtering Process

Abstract

The presence of a second reactive gas in the magnetron sputtering chamber makes the process much more complicated, and the process control much more difficult than in the case of a single reactive gas. Macroscopic models have been developed in order to explain the complex phenomena and to provide support for the process control. These models are able to explain the nonlinearities of the process and the strong coupling between the control channels.

This paper introduces a model created with the intention to of gaining a good grasp of the process, especially regarding the conditions necessary to obtain the required stoichiometry of the film deposited on the substrate. For this purpose, we modelled the formation of the desired ternary compound both directly from the available particle fluxes and from intermediary compounds. The surface of the substrate is divided into eight dynamically variable regions, covered by different compounds, each exposed to the streams of five types of particles.

We present the analytical model and provide simulation results in order to demonstrate its capability toof describeing the nonlinear phenomena, which that characterisze the two-gas sputtering process.

Open access
The Design of an Automated Plasma Diagnostic System – From Measurement to Signal Processing

Abstract

The paper deals with the design of a new plasma diagnostic system consisting of a microcontroller based power supply for automatic control of the measurement using Langmuir probe, the communication interface of the power supply and the signal processing program.

The main motivation for the design of the automated plasma diagnostic system was given by our research in different methods of plasma nitriding of steels. During the nitriding process, it is important to achieve information about the plasma, which is the medium where the heat-treatment process is going on. The new diagnostic system is able to perform measurements during the nitriding process, thus we can analyze the plasma at different temperatures and gas mixtures. The obtained voltage-current curves are recorded and transmitted to the computer, where further signal processing is performed. The paper presents the design of the power supply, the measurement results and the developed signal processing software.

Open access
Effect of Oxygen Doping on the Structure of TiN Surface Coatings

Abstract

In the present work the influence of the level of oxygen doping on the structure of TiN films was investigated by dedicated experiments. The films were deposited at 400°C in an all metal UHV device by unbalanced magnetron sputtering at the same Ar and nitrogen flow rates, but the oxygen flow rate was changed in the experiments, incorporating oxygen in the range of 4 and 20 at.%. The structure of the films was investigated by XRD, Auger electron (AES) and X-ray photon electron (XPS) spectroscopy and transmission electron microscopy (TEM). The results discovered the crystal face anisotropy in the incorporation-segregation of oxygen leading to the change of the <111> texture to <002>. The structure analysis revealed that the <002> texture is developing also by competitive growth of crystals, which is the result of the limitation of the growth of the <111> oriented crystals by the TiO2 layer developing on their growth surface by the segregated oxygen species. The oxygen incorporating in the crystal lattice on the 002 crystal faces of the <002> oriented crystals is segregated by surface spinodal decomposition, developing nm sized 3D TiO-2 inclusion both in the bulk of the columns and the column boundaries.

Open access