IMP‐8 observations of traveling compression regions: New evidence for near‐Earth plasmoids and neutral lines

An examination of IMP‐8 tail lobe magnetic field measurements has been conducted to determine whether the traveling compression region (TCR) phenomena detected by ISEE‐3 in the distant geotail, and believed to be caused by tailward moving plasmoids, are present closer to the earth. The study produced 16 examples of TCRs at distances of X = −31 to −37 RE. For two events considered in detail TCRs were observed in close association with substorm growth phase signatures in the lobes. The lengths of these TCRs are estimated to be 8–12 RE. It is our conclusion that the IMP‐8 TCR observations provide new evidence that small plasmoids and, hence, multiple reconnection neutral lines can exist earthward of X = −35 RE.