Deceleration and Ionizing Efficiency of Radar Meteors

Improved instrumentation of the radar system has permitted a more accurate analysis of range-time records of meteor echoes and enabled the meteor deceleration to be determined in a few special cases. Three illustrative examples are described in which the measured mean decelerations were −0.48, −1.1, and −1.5 km sec−2. Velocity data from a continuous wave Doppler system were also available for these meteors and are compared with the radar data. Using existing atmospheric density values and Lovell's scattering formula, it is computed that the ionizing efficiency, or the fraction of the kinetic energy of the meteor converted to ionization, is 10−6 for a 60-km/sec meteor and 10−8 for a 20-km/sec meteor. If lower values of the air density are adopted, the efficiency figures are increased and at the same time the gap is narrowed between the rates of electron production deduced from loss of mass considerations and the rates calculated from the radar data. More statistical data on radar meteors and further information on the ionizing properties of 1000 electron-volt atoms are required before definite conclusions can be drawn.