On the Initial Motion of Artificial Comets in the Ampte Releases

The early time (t < 300 s) interaction of the Ba + cloud with the solar wind during the AMPTE comet release is examined, with an emphasis on the issue of the Ba + ion magnetization. It is shown that the observed magnetic field profile is consistent with the Ba + ions being magnetized, in the sense that the cloud radius L > Ra,•+, where RBa+ is the Ba + gyroradius. As a consequence, any momentum coupling force F between the Ba + cloud and the solar wind in their relative streaming direction will produce an F x B acceleration drift in a direction consistent with the observations. The drift will cease when the cloud expands to the extent that the magnetic field inside the cloud is reduced to satisfy L < RBa+. The implications of the model to observables of the interaction are discussed.