THE PARTICIPATION OF NUCLEI IN TYPE-III-RELATED ELECTRON STREAMS

We study 27 increases of the flux of 300-800 keV electrons on board HE LIOS A or B, associated with intense type III radio bursts close to pe rihelion passages of the two spacecraft, during the solar minimum. Ele ctrons can be detected inside cones with an angular width between 30 d egrees and 60 degrees. Though only intense type III bursts are associa ted with recognizable electron events in space, such an association do es not exist for all of them; this fact and great differences in fluxe s of the individual events indicate that, apart from the intensity, al so some other characteristic of the type III burst acceleration or pro pagation process determines the resulting flux of electrons in space; the energy spectrum of the accelerated electrons is one of the likely candidates. A comparison of the electron flux in these events with the flux of 1.7-3.7 MeV nucl(-1) helium reveals very large variations of the helium/electron flux ratio, by a factor of at least 15 and possibl y much higher. We demonstrate that these variations are not caused by propagation effects in interplanetary space. Therefore, they must be d ue either to propagation effects in the solar corona or, more likely, to intrinsic variations in the relative production of electrons and nu clei in the type III burst process. An extrapolation of the observed f luxes to 1 AU shows that in only 7 of the 27 electron events studied m ight a marginal > 1.7 MeV helium flux be recognized at the Earth dista nce.