Although there are, in addition to the classic but somewhat dated books'l-, some excellent recent books on ionospheric physics and aeronomy'l-... , their scope is quite different from that of the present monograph. This monograph concentrates on the fundamental physical and chemical processes in an idealized planetary ionosphere as a general abstraction, with actual planetary ionospheres representing special cases. Such an approach appears most appropriate for a concise in troduction to the field, at a time when increasing experimental in formation on the ionospheres of other planets can be anticipated. The main purpose of this monograph, in line with that of the whole series, is to appraise where we stand, what we know and what we still need to know. It is mainly addressed to graduate students and researchers who are in the process of getting acquainted with the field. Within the scope of this monograph it would be impossible to do justice to all relevant publications. Hence, references are somewhat selective and largely limited to the more recent original papers and to authoritative reviews, the latter generally providing also detailed references regarding the historical development of the particular topic. Cgs (gaussian) units are generally used in this book, except where practical units are more appropriate. This book has evolved from a graduate course of the same title which I gave at the Catholic University of America, Washington, D. C.

Inhalt
I Neutral Atmospheres.- I.1 Nomenclature.- I.2 Barosphere: Distribution Laws.- I.3 ThermosphereThermal Structure.- I.4 ExosphereAtmospheric Escape (Evaporation).- I.5 Physical Properties of Planetary Atmospheres.- II Sources of Ionization.- II.1 Solar EUV Radiation and X-Rays.- 1I.2 Corpuscular Radiation.- II.3 Meteor Ionization.- III Thermal Structure of Planetary Ionospheres.- III.1 Departures from Thermal Equilibrium.- I1I.2 Electron and Ion Temperatures.- III.3 Heat Sources not Related to Photoionization.- IV Chemical Processes.- IV.1 General Comments.- IV.2 Recombination.- IV.3 Charge Exchange Reactions.- IV.4 Negative Ion Reactions.- IV.5 Chemical Reactions and Airglow.- V Plasma Transport Processes.- V.1 Plasma (Ambipolar) Diffusion.- V.2 Plasma Drift and Winds.- V.3 Plasma Escape.- VI Models of Planetary Ionospheres.- VI.1 Equilibrium Models.- VI.2 Observables and Derived Parameters.- VI.3 Ionospheric Regions.- VI.4 Realistic Models of Planetary Ionospheres.- VI.5 The Extent of Planetary Ionospheres.- VII The Ionosphere as a Plasma.- VII.1 General Plasma Properties.- VII.2 The Ionosphere as a Dispersive Medium.- VII.3 Ionospheric Plasma Instabilities.- VIII Experimental Techniques.- VIII.1 Remote Sensing Radio Techniques.- VIII.2 Direct Measurement Techniques.- IX Observed Properties of Planetary Ionospheres.- IX.1 The Terrestrial Ionosphere.- IX.2 The Ionosphere of Mars.- IX.3 The Ionosphere of Venus.- IX.4 The Ionosphere of Jupiter.- Appendix. Physical Data for the Planets and their Atmospheres.- References.- List of Symbols.