Proceedings PaperRemote temperature sensing of a pulsed thermionic cathode
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A diagnostic system has been developed to measure the temperature of a pulsed thermionic cathode. The thermionic cathode consists of more than 150 tungsten filaments each brought to over 2500 Kelvin in less than 10 msecs. Four optical fibers can view the cathode array and feed their light through a spectrograph (150 g/mm) into a silicon vidicon detector. An optical multi-channel analyzer (OMA) controls a pulse generator which can gate the vidicon from 70 nanoseconds to 1 millisecond. The spectrum of the tungsten source is recorded from 450 to 750 nm (across 512 channels) on four separate tracks (corresponding to each fiber). The OMA converts the count verses wavelength data to an ASCII file. A computer program has been developed which applies appropriate calibration factors to the raw data, fold in emissivity values as functions of wavelength and temperature, and provides two-color temperature measurements across the 512 channels. A simple statistical routine then determines mean and standard deviation of the temperature measurements. The system can be applied to the remote sensing of CW or pulsed thermal sources. Background measurements can be taken prior to data collection and then subtracted from raw data. Temperature values for a single pulsed tungsten filament are compared with integration of pulsed power heating.