Louis A. Rosenthal

Electrothermal Measurements of Bridgewires Used in Electroexplosive Devices

The bridgewire of an electroexplosive device is evaluated for its thermal response to impulse energy and to square-wave power. Thermal time constant and basic electrothermal parameters can be measured from the response. These parameters are useful in the study and characterization of electroexplosive devices.

Method and Apparatus for the Measurement of Electrothermal Nonlinearity

Nonlinearity in Ohmic systems due to electrothermal effects can be measured by using an asymmetrical power waveform. A dc voltage generated can be related to the thermal behavior of the resistor and its environment. The apparatus design and the experimental application to fine wire devices are presented.

Improved Frequency Meter Circuit

The familiar frequency meter circuit can be improved by employing constant current charging of the scaling capacitor between its voltage excursions. Peak current waveforms and their burden on the driving circuit are significantly reduced.

Nonlinear Bridge for Electrothermal Measurements

If an ac bridge contains one arm which is capable of responding to the instantaneous cyclic power, it will exhibit a residual third harmonic voltage at balance. This voltage magnitude is related to the electrothermal parameters of the nonlinear arm and the phase angle is related to the ability to follow instantaneous power. A practical measurements system based on these principles is described.

Thermal Transient Test Apparatus

An apparatus for evaluating the thermal transient behavior of an electroexplosive device is described. The thermal response provides nondestructive testing insight with respect to device design and behavior. Abnormal responses may be indicative of imminent failure and the apparatus provides a rapid evaluation method for quality control.

Constant current ballast

When placed in series with a voltage source of 5 V or more, the constant current ballast will pass a preset constant current independent of voltage or resistance variations. Performance and characteristics for a system capable of delivering up to 0.6 A are described.

Heat capacity measurement method for bridgewires

A single, full‐sine‐wave current pulse, of zero average value, adiabatically heats a bridgewire. Due to the electrothermal nonlinearity of the temperature‐sensitive wire, a dc voltage which can be related to lumped heat capacity appears across the bridgewire. This dc signal can be readily extracted and interpreted.

Electrolyte Conductivity Apparatus

The resistance of an electrolytic cell is measured by passing a square-wave constant current and amplifying/rectifying the voltage developed. A differential recorder provides a record of the conductivity in dynamic mixing studies. The apparatus is extremely simple and reliable and amenable to multiprobe studies.

Impulsive Firing Method for Electroexplosive Devices

Apparatus employing a half-sine-wave pulse for the adiabatic firing of electroexplosive devices is described. Basic energy equations and their interpretation are developed, and some experimental observations for characterizing an insensitive electroexplosive device are presented.

Thermal Conductance Measurement in Electroexplosive Devices by Self‐Balancing Bridge Techniques

An electroexplosive device installed as one arm of a self‐balancing bridge will yield a measurement of the thermal contact between the bridgewire and the explosive environment. This thermal conductance measurement can be used as a basic design or quality control parameter.