MEASUREMENTS OF THE TIME CONSTANT FOR STEADY IONIZATION IN SHAPED-CHARGE BARIUM RELEASES

Quantitative measurements of three solar illuminated shaped-charge bar ium releases injected at small angles to the magnetic field were made using a calibrated color television camera. Two of the releases were f rom 1989. The third release, a reanalysis of an event included in Hall inan's 1988 study of three 1986 releases, was included to provide cont inuity between the two studies. Time constants for ionization, measure d during the first 25 s of each release, were found to vary considerab ly. The two 1989 time constants differed substantially, and both were significantly less than any of the 1986 time constants. On the basis o f this variability, we conclude that the two 1989 releases showed evid ence of continuous nonsolar ionization. One release showed nonsolar io nization which could not be attributed to Alfven's critical ionization velocity process, which requires a component of velocity perpendicula r to the magnetic field providing a perpendicular energy greater than the ionization potential.