The conditions for maximized peak power extraction from a giant pulse laser are examined. In order to formulate an appropriate mathematical framework relating the various significant magnitudes, some simplifying assumptions and approximations have been used. The critical coupling conditions and the value of the resulting optimum peak power as a function of a characteristic loss factor have been determined. A distinction is made between maximum peak power and maximum energetic yield since the conditions for the achievement of both are slightly different.

A series of recent experiments has shown that the elastic scattering of a directed ion beam by residual gas is one of the dominant factors causing contamination in an electromagnetic mass separator. This phenomenon is treated numerically, based on geometrical considerations and on an appropriate and reliable interaction potential between the ions and the residual gas molecules. The result is a relation[Formula: see text]expressing the fractional contamination as a function of: the residual gas molecule concentration nr, the fractional mass difference ΔM/M, the collector slit width Δx, the configuration factor [Formula: see text] and constants (σ0 and n) which appear in the expression for the differential cross section. The reciprocal value [Formula: see text] imposes an upper limit to the enhancement factor. By performing the various integrations in a different sequence, a general expression for the transmission from source to collector is obtained. The influence of losses caused by inelastic scattering can be easily incorporated. For elements with a mass number of about 200, scattered by air and for an accelerating voltage of about 30 kv, this expression takes the form:[Formula: see text]where L is the total ion path length in the separator.

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A series of experiments has shown that both elastic scattering and charge-exchange scattering of a directed ion beam by residual gas are dominant factors causing contamination in electromagnetic mass separators. These phenomena are treated numerically for various double-direction focusing machines. The method is based on geometrical considerations and on an appropriate and reliable interaction potential between the ions and the residual gas molecules. Significant expressions for the fractional contaminations as caused by these scattering phenomena are derived. The values depend on such factors as the residual gas molecule concentration, the fractional mass difference, the collector hole area, the magnet radius, a configuration factor, and some constants which appear in the expressions for the differential cross sections. By performing the various integrations in a different sequence, general expressions for the transmission from source to collector are obtained.

The atmospheric transmittance and the astronomical refraction for low-elevation trajectories are discussed and quantitatively developed. The results are used to describe and calculate some of the fascinating atmospheric phenomena occurring shortly before and during sunset, such as the diminishing apparent luminance of the sun, its shape during sunset, and the green flash.