Orientation and structure of different components in the tail of comet West /1975n/

The orientation and structure of various components in the tail of comet West are studied from plates obtained March 4-11, 1976, with a 60-cm Schmidt telescope. A wavelike structure appears on March 10 and 11 in the type I tail. The mechanism for these waves is very probably excitation of surface waves in the ion tail due to Kelvin-Helmholtz instability at the interface between the comet plasma and the solar wind. According to this model, the measured wavelengths increase with distance from the comet head. The average wavelength of observed waves is 0.009 plus or - 0.002 AU.