In precis, we will be able to finish that the contributions of the various ionization strategies to the whole ionization expense for the main plentiful interstellar species are essentially recognized. The ionization of the noble gases He and Ne is sort of thoroughly ruled via photoionization, while for H charge-exchange with the sun wind is most crucial. For different species, resembling zero and Ar, either tactics give a contribution considerably. Electron influence ionization can in general give a contribution by means of '" 10% to the entire expense within the internal sun method. simply because direct measurements of the sunlight EUV flux usually are not but regularly to be had, the adaptation of the ionization expense over the sunlight cycle nonetheless incorporates a quite huge uncertainty. the hot measurements of pickup ion distributions and of the impartial helium gasoline supply an self sustaining device to figure out the whole ionization price that may be used to go calibrate with the implications bought for the person ionization procedures. Acknowledgements The authors are thankful to M. Allen for offering us with new facts on photoioniza­ tion cross-sections compiled by means of him. We thank additionally M. Gruntman for drawing our awareness to and help in gathering the latest facts on charge-exchange cross-sections. D. R. used to be supported through provide No. 2 P03C. 004. 09 from the Com­ mittee for clinical examine (Poland). This paintings used to be additionally supported partly via NASA agreement NAS7-918, NSF furnish INT-911637, NASA provide NAGW- 2579.