The purpose of this paper is threefold: to discuss electronic techniques appropriate to high-resolution electrical conductivity measurements in the detonation products of condensed explosives; to present evidence to show that if the detonation products contain free carbon, that carbon is the main conductor of electricity; and to demonstrate the usefulness of the measurement technique to explore reaction-zone structure.
A circularly curved piece of LX-17 of square cross section was detonated at one end with a plane-wave lens. Detonation velocities along the inner and outer edge were measured with pins and a streak camera measured the detonation front curvature on the end face. A steady state``shadow'' or inner curve velocity of 7.13 mmyms was measured for rib radii of 89 mm and 114 mm. Time constants for the change to steady state on the curve were derived. The outer time constant is set by the time for the energy to¯ow across the explosive, not by the reaction zone length, and this results in a considerable tilt of the front. The tilt causes the leading point of the front to move far inward, close to the inner edge. A simple theory for reaction zone lengths is used ®rst on slabs and then on the rib. Because the tilt directs the front away from the inner edge, the inner edge of the rib can sustain a shadow velocity lower than the failure velocity of the cylinder or slab. The rib has been modeled with Ignition and Growth in DYNA2D, producing a smooth set of detonation velocities that are slightly low. The production betayprogram burn package in VHEMP produces a less smooth set of velocities that are too high.
A low-cost capacitance hygrometer capable of measuring steady-state and some transient changes in the output of medical humidifiers is introduced and evaluated. The method of operation is presented in detail, as is a comparison with the widely used gravimetric standard. The hygrometer produces results within 7% of those given by the gravimetric method when using units of percentage relative humidity (which give the widest discrepancies). This is shown to be an acceptable figure for the proposed application. Problems encountered when converting units of humidity are discussed in detail and methods of conversion explained.
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