Plasma, inert gases

Gas composition is an important processing variable in ion plating. The gas used for an inert plasma should be free of contaminants such as water vapor and oxygen that will become activated in the plasma. Inert gases can be purified using heated reactive svufaces such as copper, titanium, or uranium chip beds. Reactive plasmas should be free of contaminants. In reactive gases or gas mixtures, water vapor can be removed by cold traps utilizing zeolite adsorbers. 

The treatment protocols identify the base plasma inert gas chemistry, assisted by a reactive oxygen component, which was determined to optimize treatment results relative to the solar cell application. For example, specific peel adhesion benchmarks were targeted for PVC adhesion to a solvent-base adhesive. To meet cleanliness benchmarks, pre-specified low level organic particle contamination concentrations were established to optimize lamination adhesions. The required power densities applied to each protocol were predetermined with regard to the required surface effect by laboratory trials on commercial roll-to-roll and tangential atmospheric plasma surface treatment systems. 

Oxygen and nitrogen also are deterrnined by conductivity or chromatographic techniques following a hot vacuum extraction or inert-gas fusion of hafnium with a noble metal (25,26). Nitrogen also may be deterrnined by the Kjeldahl technique (19). Phosphoms is determined by phosphine evolution and flame-emission detection. Chloride is determined indirecdy by atomic absorption or x-ray spectroscopy, or at higher levels by a selective-ion electrode. Fluoride can be determined similarly (27,28). Uranium and U-235 have been determined by inductively coupled plasma mass spectroscopy (29). 

In plasma chromatography, molecular ions of the heavy organic material to be analy2ed are produced in an ionizer and pass by means of a shutter electrode into a drift region. The velocity of drift through an inert gas at approximately 101 kPa (1 atm) under the influence of an appHed electric field depends on the molecular weight of the sample. The various sonic species are separated and collected every few milliseconds on an electrode. The technique has been employed for studying upper atmosphere ion molecule reactions and for chemical analysis (100). 

As in the case of many metal—ahoy systems, weld ductihty is not as good as that of the base metal. Satisfactory welds can be made in vanadium ahoys provided the fusion zone and the heat-affected zone (HAZ) are protected from contamination during welding. Satisfactory welds can be made by a variety of weld methods, including electron-beam and tungsten-inert-gas (TIG) methods. It is also likely that satisfactory welds can be made by advanced methods, eg, laser and plasma techniques (see Lasers Plasma technology). 

Plasma Plating—deposition on critical areas of metal coatings resistant to wear and abrasion normally this is done by means of a high velocity and high-temperature ionized inert gas jet. 

In the presence of an inert gas, such as He or Ar, crosslinking can be introduced into the surface layer of material by plasma treatment. Hansen and Schon-horn [60] named this Crosslinking by Activated Species of Inert Gases (CASING). As a result, bond strength is enhanced because crosslinking strengthens the surface layer. 

It can be welded by resistance, tungsten-inert gas (TIG), plasma arc and electron beam techniques. To protect the metal from attack by air, resistance welding is carried out under water and the TIG method is best performed in a chamber of argon. The latter three methods produce ductile welds that equal the base metal in most of its characteristics. 

Plasma spraying Metals, or refractory materials or composites are applied by melting in an ionised inert gas M, tantalum, molybdenum, alumina, zirconia M2 a variety of metallic substrates... 

The plasma jet can be cooled rapidly just prior to coming in contact with the substrate by using a blast of cold inert gas fed into an annular fixture. Gaseous boron or phosphorus compounds can be introduced into the gas feed for the deposition of doped-semiconduc-tor diamond. 

In the authors experience, the amount of carbon dioxide in 10 microliters of blood can readily be determined by adding the blood to an acid, through which bubbles an inert gas. The CO2 is then brought into the field of a long cuvette, of approximately 20" in length, and the carbon dioxide measured at the near infrared with a filter instrument. Instrumentation can be designed readily for measurement of the carbon dioxide content of as little as 1 l of plasma with this principle at the rate of approximately 40-60 per hour. 

It is necessary to supply a spray into the plasma jet, in order to excite the elements. This has presented some difficulty and it is a n stery to the author as to why the plasma jet has not been more widely applied for the analysis of sodium potassium, calcium and magnesium. It has the advantage of safety, in that one inert gas (argon) would be used, and high sensitivity. In addition, four elements, calcium, magnesium. 

In a direct-current plasma source (DCP) initial heating of an inert gas, usually argon, is produced by a dc-arc. Experimentally it is arranged for the plasma to be established in a high-velocity gas stream. When the edges of the plasma are cooled with an inert gas vortex, the cooler outer parts have... 

Gas. Each type or nominal composition of the inert gas used for shielding or plasma shall be documented in the WPS and supported by a PQR. Backing gas shall be used in accordance with ASME BPV Code Section II, Part C, specification SFA-5.32. 

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