Plasma heating

Although o2one can be formed in certain chemical reactions, eg, F2 + H2O and P + O2, and by rapid quenching of plasma-heated oxygen (>3000° C) with Hquid oxygen, these methods have no commercial importance. 

Surface Modification. Plasma surface modification can include surface cleaning, surface activation, heat treatments, and plasma polymerization. Surface cleaning and surface activation are usually performed for enhanced joining of materials (see Metal SURFACE TREATMENTS). Plasma heat treatments are not, however, limited to high temperature equiUbrium plasmas on metals. Heat treatments of organic materials are also possible. Plasma polymerization crosses the boundaries between surface modification and materials production by producing materials often not available by any other method. In many cases these new materials can be appHed directly to a substrate, thus modifying the substrate in a novel way. 

PEAT, Inc., has developed the thermal destruction and recovery (TDR) system for the treatment of medical, hazardous, and radioactive wastes. An electronic plasma heating system is used to break down wastes into three phases. The ceramic, metal, and off-gas phases can aU be used as commercial products. The technology has been evaluated in treatability studies on infectious medical waste. Department of Defense (DOD) ammunition and energetic materials, U.S. Department of Energy (DOE) weapon components, ash, electronic scrap, batteries, asbestos, and organic compounds. 

In Situ Plasma Vitrification In situ plasma-heated nontransferred arc vitrification systems discussed in the RIMS database include the Georgia Institute of Technology Construction Research Center s in situ plasma vitrification system (T0343) and the Teton Technologies, Inc., in situ waste destruction and vitrification system (T0786). A cost estimate is included in the Georgia Institute of Technology in situ plasma vitrification system. 

Exercise. Derive from (5.8) an equation for the velocity distribution (which is the relevant quantity for plasma heating). 

Thermal treatment processes use energy to destroy or decontaminate waste. These technologies include low or high energy thermal processes. Several types of thermal processes include flame combustion, fluidized bed combustion, infrared incineration, pyrolysis and plasma heat systems. 

Atomization is accomplished by direct heating of the electrode by the electron component of the discharge current and by the discharge plasma. Then, ionization of these atoms which occurs in the plasma is due mainly to plasma heating by electrons accelerated by the electric field. Chemical reactions can also take place in the plasma, leading to the formation of clusters. 

Unfortunately, the beam heats up the plasma considerably and increases the momentum of the plasma column, influencing the rotational speed of the plasma as well. Therefore, charge exchange spectroscopy can be used only in discharges with additional heating. In ohmic plasmas and plasmas heated by electromagnetic waves X-ray spectroscopy is the only diagnostic to determine the ion temperature, as well as the plasma rotation. 

The ICP is a stable argon plasma heated by inductive coupling of argon cations and free electrons, but is perhaps best thought of as simply a hot flame. Temperature measurement indicates that the plasma has a temperature approaching 6-7000°K. 

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