Observation and Study of the Tornado-like Prominence on August 29,1990

On August 29, 1990, a tornado-like prominence erupted at the eastern limb of the sun(E90, S12, NOAA/USAF 6241). The morphological analysis and spectral diagnosis of the prominence have been given in this paper. It is found that:(1) The material in the prominence spirally rose in the regular way, then after reaching the climax, it irregularly dropped in succession. The helix motion is possibly explained as the interaction between the magnetic field frozen in the prominence and the electric field caused by the double pole diffusion in plasma.(2) The tornado-shaped prominence had the shape changed quickly, and finally appeared as a regular loop structure.(3) The shape of a prominence and its changes with time could be an important factor for studing its properties. A qualitative model of the magnetic configuration which gives a possible explanation of the observed results has been proposed in this paper.