Region of cometary ions in the head of the Halley comet from the data of the Vega-2 space probe

Experimental data are presented and peculiarities of physical characteristics of comet plasma are discussed. Experimental data are obtained by wide-angle (14x32 deg) electrostatic analyser oriented by space probe velocity vector relatively the comet. Ion energy spectra were measured every second in 120 logarithmically arranged energy intervals in the 15-3500 eV/Q (Q-charge number) energy range with energy resolution ΔE/E=0.055. Possible causes of quasiperiodic modulation of heavy ion concentration with the period of 10 c observed in comet plasma are discussed