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An Experimental Investigation of the Performance of the Nitrogen Tetroxide-Hydrazine System in the Oxidizer-Rich and Fuel-Rich Regions
The results of an experimental program directed toward determining some of the operational characteristics of the nitrogen tetroxide-hydrazine propellant system under oxidizer-rich and fuel-rich conditions are reported. Data are presented for the mixture-ratio ranges of 0 to 0.55 at a nominal chamber pressure of 300 psia and characteristic chamber length of 250 in., and at mixture ratios of 5.9 to 13.0 at nominal chamber pressures of 400 and 500 psia and characteristic chamber lengths of 100 and 3900 in. The relationship of the actual performance data obtained in each region with those predicted from thermochemical performance calculations is presented. From this comparison, it is concluded that in neither region are equilibrium conditions obtained and that utilization of performance data obtained from assumptions of equilibrium will lead to serious errors. In the oxidizer-rich region investigated, temperatures considerably below those predicted occur throughout the range of mixture ratios investigated because of the lack of exothermic dissociation of the nitrogen oxides. In the fuel-rich region, below a mixture ratio of 0.3, temperatures considerably higher than those predicted occur because of the lack of endothermic dissociation of ammonia
External losses in photoemission from strongly correlated quasi two-dimensional solids
New expressions are derived for photoemission, which allow experimental
electron energy loss data to be used for estimating losses in photoemission.
The derivation builds on new results for dielectric response and mean free
paths of strongly correlated systems of two dimensional layers. Numerical
evaluations are made for (Bi2212) by using a
parametrized loss function. The mean free path for Bi2212 is calculated and
found to be substantially larger than obtained by Norman et al in a recent
paper. The photocurrent is expressed as the convolution of the intrinsic
approximation for the current from a specific 2D layer with an effective loss
function. The observed current is the sum of such currents from the first few
layers. The photo electron from a specific layer is found to excite low
energy acoustic plasmon modes due to the coupling between the layers.
These modes give rise to an asymmetric power law broadening of the photo
current an isolated two dimensional layer would have given. We define an
asymmetry index where a contribution from a Luttinger lineshape is additive to
the contribution from our broadening function. Already the loss effect
considered here gives broadening comparable to what is observed experimentally.
A superconductor with a gapped loss function is predicted to have a
peak-dip-hump lineshape similar to what has been observed, and with the same
qualitative behavior as predicted in the recent work by Campuzano et al.Comment: 17 pages, 10 figure
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