Measured Pulse Duration Research Articles

Ejecta pulsing of subscale solid propellant rocket motors

This paper presents results obtained in a program designed to develop guidelines for pulsing solid propellant rocket motors to determine their susceptibility to finite amplitude disturbances. A series of motor firings was conducted in which sphetes of different sizes and materials were ejected through the nozzle to simulate inf light partial nozzle blockage due to igniter, propellant or other combustion chamber material fragments. Simple laboratory scale solld rocket motors with full and partial length grains were utilized. All of the motors tested were triggered into sustained nonlinear instability. A simple analysis was developed to calculate the velocity of the ejecta and pulse duration. Gaod ogreement between predicted and measured pulse durations was obtained. Two methods were developed for predicting initial ejecta induced pulse amplitudes: a simple model based on linear wave propagation theory and the assumption of quaslsteady nozzle behavior, and a numerical model which utillzes the quasi-steady nozzle assumption to provide a nozzle entrance boundary condition to a comprehensive combustion chamber nonlinear instability analysis. Comparisons of theoretical predictions with experimental data for both pulse amplitude and the motor response to pulsing are presented. Tht nonlinear instability analysis was found to be capable of predicting the complete range of nonlinear behavior observed in motor response to ejecta pulsing. Good agreement between measured and predicted initi pulse (amplitude and harmonic content), waveform evo ution, growth and decay rates, and DC shift was obtained. p'

CW mode-locked dye lasers for ultra fast spectroscopic studies

Continuously working dye lasers have produced pulses as short as 0.3 ps. The properties of passively and actively mode-locked dye lasers are described and compared. Methods of measuring pulse duration and applications of these lasers to photophysics and photobiology are discussed.

Measuring pulse durations below 1?sec with Ch3-34A (Ch3-34) frequency counter

Measuring pulse durations below 1?sec with Ch3-34A (Ch3-34) frequency counter

A method of measuring pulse duration

The pulse under investigation and a timing wave consisting of a succession of narrow triangular pulses of controllable frequency are simultaneously displayed on a double-beam sampling oscilloscope. Adjacent timing pulses are aligned to the leading and trailing edges of the pulse being measured; the duration of the pulse, being then identical with the period of the timing wave, is obtained from a digital frequency meter monitoring the timing-wave frequency. Pulse durations in the range 20 to 100 ns may be determined with an uncertainty of ± 100 ps. For pulses of durations extending to several microseconds the uncertainty is within ± 0.1%. The method has particular application in pulse-bandwidth measurements on television and other waveform transmission systems having pulse bandwidths in the range 125 kHz to 25 MHz. Using ancillary amplitude-measuring equipment, such measurements can be accomplished with uncertainties of ±1% or better.

Integral Technique for Measuring Pulse Duration

Integral Technique for Measuring Pulse Duration