Kaufman Source

In ion beam deposition, hydrocarbon gas such as methane or ethyene is ionized into plasma by an ion source such as the Kaufman source [3]. The hydrocarbon ions are then extracted from the ion source and accelerated to form an ion beam. The ions and the unionized molecules condense on the substrate surface to form DEC coating. However, in this method, ionized ratio of precursor gases could hardly exceed 10 %. In order to obtain a better quality of DEC coatings. 

In contrast to the d.c. or microwave plasma apparatus, the sample environment produced by these directed beam sources has been reasonably well characterized. Studies of Kaufman source operation (Sharp et al., 1979) have established that H beams are typically composed of mixtures of H+ and H2+ ions and a roughly equal mixture of energetic neutrals. The ion energy spectrum of such a source is fairly sharply peaked at the maximum energy at low acceleration voltages (150-500 eV) but spreads out considerably if the source is operated at voltages above 1000V. 

Fig. 2. Schematic illustration of a Kaufman source ion beam system (Sharp et al., 1979).

If a pure ion beam has been extracted from an ion source, electrons may be added to the ion beam to form a plasma beam that will not diverge and not cause a charge buildup on the target surface. In the Kaufman source, these electrons are from a hot filament ( neutralizer filament ). It should be noted that the ions are not neutralized. Instead, the beam is volumetrically neutral due to the addition of the electrons. This plasma beam consists of high energy ions and low energy electrons. 

Harper J M E, Cuomo J J and Kaufman H R 1982 Technology and applications of broad-beam ion sources used in sputtering. Part II. Applications J. Vac. Sc/. Technol. 21 737-56... 

H. R. Kaufman and R. S. Robinson, Operation of Broad-Beam Sources, Commonwealth Scientific, Alexandria, Va., 1987. 

The residence time of " Th, with respect to removal by scavenging, can be calculated by assuming that the dominant source of " Th is by decay of in situ (Kaufman et al. 1971 Porcelli et al. 2001)... 

Source Kaufman, J.E. (ed.) IES Lighting Handbook, Illuminating Engineering Society, New York,... 

The passivation of dry-etching damage by low energy hydrogen implantation from a Kaufman ion source (0.4 keV) has also been reported (Singh et al., 1984b). The Si samples were either initially bombarded with a... 

Osmond, J. K., Kaufman, M. I., Cowart, J. B., Mixing volume calculations, sources and aging trends of Floridan aquifer water by uranium isotopic methods, Geochim. et Cosmochim. Acta, 38, 1083-1100 (1974). 

Although the majority of attention in discussions on the origins of BIFs has been on the oxide facies, siderite facies rocks are equally important in many BIF sequences. Reaction of Fe(II)aq and dissolved carbonate with hematite to form siderite and magnetite has been hypothesized to be an important diagenetic process in marine basins during formation of some BIFs if sulfate contents were low (e.g., Klein and Beukes 1989 Beukes et al. 1990 Kaufman 1996 Sumner 1997). In Figure 18 we assume that Fe(II)aq was derived either from MOR sources or DIR, or a combination of the two, which reacted with ferric oxide precipitates to form magnetite or dissolved carbonate to produce siderite. 

Qi, Z., and Kaufman, A. Low Pt loading high-performance cathodes for PEM fuel cells. Journal of Power Sources 2003 113 37--43. 

Spectral lines are often characterized by their wavelength and intensity. The line intensity is a source-dependent quantity, but it is related to an atomic constant, the transition probability or oscillator strength. Transition probabilities are known much less accurately than wavelengths. This imbalance is mainly due to the complexity of both theoretical and experimental approaches to determine transition probability data. Detailed descriptions of the spectra of the halogens have been made by Radziemski and Kaufman [5] for Cl I, by Tech [3] for BrIwA by Minnhagen [6] for II. However, the existing data on /-values for those atomic systems are extremely sparse. 

Relevant data extracted from activity measurements in the Fe-C phase were later included in the assessment by Zener (1946) and Darken and Smith (1951). All this work followed a traditional approach solely based on thermodynamic data derived under equilibrium conditions. By contrast, Kaufman and Cohen (1958) showed that the data of Johannson (1937) were more consistent with information derived from Fe-based martensite transformations than the interpretation used by Darken and Smith (1951). Together with the work of Svechnikov and Lesnik (1956) this was a notable attempt to combine thermodynamic information derived from low-temperature metastable transformations with those from more traditional sources. 

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