Grzegorz Raniszewski

Influence of Plasma Jet Temperature Profiles in Arc Discharge Methods of Carbon Nanotubes Synthesis

One of the most common methods of carbon nanotubes (CNTs) synthesis is application of an electric-arc plasma. However, the final product in the form of cathode deposit is composed of carbon nanotubes and a variety of carbon impurities. An assay of carbon nanotubes produced in arc discharge systems available on the market shows that commercial cathode deposits contain about 10% CNTs. Given that the quality of the final product depends on carbon–plasma jet parameters, it is possible to increase the yield of the synthesis by plasma jet control. Most of the carbon nanotubes are multiwall carbon nanotubes (MWCNTs). It was observed that the addition of catalysts significantly changes the plasma composition, effective ionization potential, the arc channel conductance, and in effect temperature of the arc and carbon elements flux. This paper focuses on the influence of metal components on plasma-jet forming containing carbon nanotubes cathode deposit. The plasma jet temperature control system is presented.

Synthesis of Carbon Nanotubes in Thermal Plasma Reactor at Atmospheric Pressure

In this paper, a novel approach to the synthesis of the carbon nanotubes (CNTs) in reactors operating at atmospheric pressure is presented. Based on the literature and our own research results, the most effective methods of CNT synthesis are investigated. Then, careful selection of reagents for the synthesis process is shown. Thanks to the performed calculations, an optimum composition of gases and the temperature for successful CNT synthesis in the CVD (chemical vapor deposition) process can be chosen. The results, having practical significance, may lead to an improvement of nanomaterials synthesis technology. The study can be used to produce CNTs for electrical and electronic equipment (i.e., supercapacitors or cooling radiators). There is also a possibility of using them in medicine for cancer diagnostics and therapy.

Influence of Contaminants on Arc Properties during Treatment of Polluted Soils in Electric Arc Plasma

Abstract One of the most effective method of contaminated soil utilization is thermal plasma arc treatment. Assuming that electric arc is immersed under the ground level - it is placed only in mineral atmosphere. Components from utilized soil are the source of these minerals. A furnace with the immersed arc-plasma has been elaborated for solid waste treatment purposes. To establish the influence of particular minerals on the discharge, a model where particular elements can penetrate the arc plasma channel has been made. The discharge takes place in a mineral atmosphere, similarly to the immersed arc plasma waste utilization. Subsequently, the arc temperature was measured. A measurement based on the two spectral lines method with Abel inversion, independent of the plasma chemistry was used. A new utilization method of soil wastes using an immersed arc with efficiency up to 98% has been described. Experimental results from the research has been presented and mineral plasma composition has been calculated and compared.

Arc Plasma for Materials Detoxification and their Conversion

Abstract The paper presents own experience examples of plasma employing methods for gas and fluid waste destruction and solid waste conversion into valuable materials or products. Three of own design plasma reactors ROTARC, SPIRARC, PDUCR have been successfully used in the laboratory testing for gas and fluid chlorinated wastes and spent fluid chemical reagents destruction. A new approach to utilisation of mineral wastes using electric arc has been also presented. An immersed arc-plasma furnace IAF has been designed for this purpose. The conversion of toxic waste to the form of environmentally friendly and useful building materials is presented.

Optimization of Magnetic Field-Assisted Synthesis of Carbon Nanotubes for Sensing Applications

One of the most effective ways of synthesizing carbon nanotubes is the arc discharge method. This paper describes a system supported by a magnetic field which can be generated by an external coil. An electric arc between two electrodes is stabilized by the magnetic field following mass flux stabilization from the anode to the cathode. In this work four constructions are compared. Different configurations of cathode and coils are calculated and presented. Exemplary results are discussed. The paper describes attempts of magnetic field optimization for different configurations of electrodes.

Generating of dispersed thermal plasma

Two models of plasma generator /reaction chamber/ with divergent channels have been designed and used in the laboratory testing. The arc was magnetically driven between co-axial electrodes of different shape and configuration making the nozzle conical or spiraling. These resulted in fast arc expansion and a thermal tail formation called the dispersed plasma. Some diagnostic techniques including spectroscopy were employed. These plasma reactors named ROTARC and SPIRARC have been successfully used in thermal destruction of chlorinated wastes. The destruction efficiency higher than 99,999% has been achieved. In this paper the plasma generators design principle and test results aimed to establish the arc discharge stability criteria are presented.

Influence of mineral components on electric arc plasma parameters

The electric arc in gas-metal atmosphere appears in many applications. Determining of metal vapor density in plasma is essential for mathematical modeling of plasma behavior as a conducting medium. The circuit breakers are an excellent example of influence of metals on plasma conductivity due to contamination of evaporating electrodes. Low value of the ionization potential of metallic contacts leads to the AC arc reignition at the current zero that in turn cause higher erosion of contacts.