A General Formula for the Estimation of Dielectronic Recombination Co-Efficients in Low-Density Plasmas.

Abstract

1588 LETTERS TO THE EDITOR Vol. 141 tion will be concerned only with the results as they pertain to the influence of the satellite lo. Figure 1 shows the number of 26.3-Mc/s events observed as a function of the position of lo in its orbit measured from superior geocentric conjunction. The data in Figure 1 represent a total observing period of about 2 months as opposed to a period of nearly 4 years for the HAO data, and yet an apparent increase in the occurrence probability when the departure of lo from superior geocentric conjunction is near 80° or 230° is still easily seen. The data are broken into three groups corresponding to the three decametric regions in system III longitude. Over 66 per cent of all 26.3-Mc/s events associated with region 1 (40° < Xm < 180°) were observed when lo was between 60° and 90° from superior geocentric conjunction. Of the noise events occurring in region 2 (180° < Xm < 270°), 52 per cent were observed when the position of lo was between 200° and 270°. Similarly 55 per cent of the events associated with region 3 (270° < Xm < 345°) occurred when the position of lo was between 200° and 270° from superior geocentric conjunction. The data in Figure 1 are for all events stronger than 10-23 W/m 2 /(c/s), the sensitivity of the Clark Lake observations. If one considers only those events of flux densities exceeding 5 X 10-22 W/m 2 /(c/s), however, 57 per cent of the events are found to occur when lo was between 60° and 90°, and 25 per cent of the events fall in the interval for lo's position being between 200° and 270° from superior geocentric conjunction. In summary, the Clark Lake observations tend to confirm the apparent influence of lo on the 26.3-Mc/s emissions from Jupiter and show an enhanced probability of emission when lo is near 80° or 230° from superior geocentric conjunction. The first emission region on Jupiter appears to be associated with the 80° peak in the position of lo, whereas the two later regions have a high probability of emission when lo is near 230°. The authors gratefully acknowledge the guidance and assistance of W. C. Erickson, of the University of Maryland.