RADIOMETRIC TEMPERATURE MEASUREMENTS OF SHORT DURATION EVENTS.

Book excerpt: A 4-color spectroscope using the wavelengths 0.546, 0.577, 0.623, and 0.750 microns was used to determine the surface temperatures of electrically exploded wires and aluminum projectiles of velocity 4,500 m/sec. Several values of initial capacitor energy, pressure, and ambient atmosphere were used with the exploded wires. The projectiles were observed in a normal atmosphere at 710 mm Hg. The temperatures observed for exploded wires for an initial capacitor energy of 0.8 joule in air at 710 mm Hg were: 3825! 25 K for aluminum, 3100! 75 K for copper, and 3700! 25 K for tungsten. For an aluminum projectile in air at 710 mm Hg at a velocity of 4,500 m/sec, the temperature observed was 3250! 50 K. The spectral distribution in all cases was observed to be black body and could be fitted by the Wien radiation law. Calibration was achieved using a tungsten ribbon lamp. Blackbody radiation data from the Planck radiation law are also given using the new value for the second radiation constant, C2 = 14,388 microns K for temperatures from 2000 to 4000 K and wavelengths from 0.500 to 0.800 microns.