Measurements of temperature using infrared radiation have become common in industry. They are used in process control for materials ranging from steel to glass to silicon, in machinery to monitor component temperature and performance, and to predict component failure. We developed a rapid, noncontact method of accurately measuring the temperature and the spectral emissivity of a surface. Inclusion of the emissivity in the measurement makes it possible to achieve high-precision results. In our method, the power spectrum emitted by a surface is measured first by a multichannel spectrometer; the surface is then illuminated by a full-spectrum light source with a known spectrum, and the sum of the emitted and reflected power from the surface is measured. The data from the two measurements and the governing relations for the radiation and reflection processes are then combined to generate a set of curves that intersects near a solution point, which yields the temperature and the emissivity in the range of wavelengths of one of the channels. The emissivity in the other channels is readily calculated and yields the wavelength-dependent emissivity of the surface. The accuracy of the method for very rapid (submicrosecond) measurements is approximately 1% or less. We named this method the spectrum method because it uses the spectrum of both the emitted and reflected light to make the calculation. The method is more accurate than a grey body calculation because the wavelength-dependent emissivity is an integral part of the calculation of the surface temperature. The accuracy of the temperature and emissivity measurements can be calculated for a system containing five or more channels. We discuss the sources of errors and quantitatively assess their effect. Relative as well as absolute values of the channel emissivities have a significant effect on errors in the emissivity and temperature measurements. This temperature diagnostic has been tested on a tabletop device that allows us to make quick and reproducible measurements.

No abstract

Three experiments done over twenty years on gaps in LX‐17 are described. For the detonation front moving parallel to the gaps, jets of gas products were seen coming from the gaps at velocities 2 to 3 times greater than the detonation velocity. A case can be made that the jet velocity increased with gap thickness but the data are scattered. For the detonation front moving transverse to the gap, time delays were seen. The delays roughly increase with gap width, going from 0–70 ns at “zero gap” to around 300 ns at 0.5–1 mm gap. Larger gaps of up to 6 mm width almost certainly stopped the detonation, but this was not proved. Real‐time resolution of the parallel jets and determination of the actual re‐detonation or failure in the transverse case needs to be achieved in future experiments.

No abstract

A total of seven shots were fired at the HyperSpectral Sciences, Inc. firing site in Cinebar, WA, in support of the program to elucidate the internal electric breakdown phenomena. Three experiments were full-up HFCG shots. All of the HFCG shots broke down, while the last one exhibited the clearest example of "classical" breakdown. The correlation of the computer model threshold calculation with the last shot is quite good. The use of framing and streak cameras as a diagnostic has proved viable; the contact point as well as the breakdown are very visible. It was found that the electrical arcs that result from the breakdowns do not move. They are overrun by the contact point. The compressed gas in the interior of the HFCG must be taken into account. While it seems quite evident that the breaks are from the stator to the armature, our evidence cannot prove the point. Details of the firing arrangements, the data recovery methods, and the results with comparisons to theory [1], [2], and [3] are presented.