Hot, diamagnetic cavities upstream from the Earth's bow shock

摘要: An unusual type of plasma structure was observed by ISEE-1 and -2 upstream from the earth's bow shock on eight occasions during first 2 years mission. These events typically last approx.1-2 minutes have very striking magnetic field signatures. The magnitude is strongly reduced within events, with low-field region (the cavity) flanked one or both sides strong enhancements. Within cavity density compared to ambient solar wind, flow velocity much smaller deflected, direction deflection correlated spacecraft location relative sun-earth line. In addition, ion electron temperatures are high (T/sub i/ approx.2 x 10/sup 7/ /sup 0/K T/sub e/ approx.10/sup 6/ 0/K). total pressure an order higher than in this imbalance appears be only partially offset tension. structures interpreted as hot, probably expanding, diamagnetic cavities a scale size few R/sub E/, essentially convecting wind. A number possible originsmore » for been explored, but no clear completely satisfying explanation has found. most promising possibility considered that represent wind signature magnetopause flux transfer events.« less