Abundance ratios of He-4/2+//He-3/2+/ in the solar wind

The ion composition experiment aboard the Isee 3 spacecraft has been used to measure the He-4(2+)/He-3(2+) ratio in the solar wind. Using 4334 observations made between Aug. 18 and Nov. 24, 1978, and March 24 and Aug. 25, 1979, the average ratio He-4(2+)/He-3(2+) was 2.1 + or - 0.2 x 1000, in agreement with previous foil measurements. Individual observations vary widely from the average and the low He-4(2+)/He-3(2+) ratios occur at times of low He-4(2+) flux.