Ion distribution function dynamics near the strong shock front (Project Intershock)

Thestructureof the iondistributionfunctiondownstreamof thebowshockfrontisanalyzedwith theuseof ionenergyspectrameasuredwithhightemporalresolution(0.64sec) by severaldifferentlyorientednarrow—angleelectrostatic analyzersonboardPrognoz-1OIntercosmossatellite.Withina relativelyextendedregiondownstreamof the shockthe ionenergyspectraexhibitfinestructureconsistingof severalrapidlyvaryingnarrow peaks. Someevidenceexiststhatthe iondistributionfunctionbehinda strongquasiperpendicular shockconsistsof manynarrowbunches. Theelectrostaticpotentialjumpat thefrontof an obliqueshockmayoccurin a distanceof about2 km. Observations of the iondistributionfunctionis an importanttestand information source forthetheoreticaldescriptionof thecollisionlessshock. Observationsof doublepeakedionflowat theshockfront/1/provedtheimportanceof thereflectedbeamin the shockprocesses.Subsequentobservationson ISEE—1and—2 /2,3,4/and Prognoz-8/5/as wellas theoreticaldevelopments(e.g.,/6/)showeda moredetailedpictureof the reflectedbeamdynamicsand theroleof reflectedinnsin thedissipativeprocessesnear theshockfront. Itwasone of the importanttopicsof the INTERSHOCKproject/7/to provideadditionaldataon thestructureof theiondistribution function. Itwasexpectedthatthehighertemporalresolutionwouldhelpthedevelopmentof the incompletely solvedproblemof thedissipationin theshock.