Gas Discharge Physics, RAIZEK Y. P., 1991~ 449 pp. Springer. Heidelberg, DM 148.00 hb, ISBN 3-540-19462-2.

From time to time it is valuable for solar-terrestrial plasma physicists to cast their thoughts more widely. A good way of doing so, in the direction of the theory and the modus oper- andi of laboratory plasma devices, is this up-to-date text. Based upon a longer book published in Russian in 1987 it is clearly and refreshingly written-but in cgs units, with pressures in Torr. However, no magnetic fields, or their effects. are considered.

It starts with a discussion of an evacuated d.c. discharge tube, and the phenomena of breakdown, electron avalanche, and glow, arc or corona discharge. The positive column of a glow discharge is a nonequilibrium plasma, whereas that of a high-pressure arc is an equilibrium plasma. An example of an a.c. discharge in the optical range is gas breakdown by laser radiation. Chapters 2 and 3 treat the behaviour of a ‘mean’ electron in an ac. field, introducing the concepts of effective collision frequency, drift velocity, mobility, Cou- lomb cross-section, energy balance, relaxation and diffusion, similar properties for ions, ambipolar diffusion, and the definition of a plasma. They cover the hydrodynamic equa- tions for an electron gas, the motion ofelectrons in oscillating fields, electromagnetic wave propagation and the dielectric permittivity of a plasma, the critical plasma frequency (for reflection), and the plasma frequency. Chapter 4 is on the production and decay (loss) of charged particles, diffusion, and electron emission from solids-work functions, therm- ionic emission and secondary emission.

The kinetic theory for electrons in a weakly ionized gas in an electric field is the tooic of Chauter 5. Liouville’s theorem, the collision integral, elastic and inelastic collisions are covered. as are numerical results for nitrogen and air. The theory of probes for studying the gas discharge plasma are considered in Chapter 6.

Paschen curves (breakdown potentials), breakdown in microwave fields, and sparks in air more than 60 m long obtained using a 5GW mean power neodymium laser in 1976 are discussed in Chapter 7. The next chapter covers stable glow discharges. their current-voltage characteristics, the dark discharge, and discharge in a fast-flowing gas. Chapter 9 is on glow discharge instabilities, their growth rates and their consequences such as striations and filamentation. Chapter IO is on the arc discharge in air. Chapter I1 is on producing and sustaining an equilibrium plasma by ac. fields, for example, the inductively coupled RF discharge or plasmatrons. Spark and corona discharges (such as in lightning) are the topic of Chapter 12, with capacitively couoled RF discharges being discussed in Chapter 13. Dis- charges in high power coltinuous wave CO, lasers are covered in the final chapter.

M. J. RYCROFT

Cranfield Institute of Technology

Satellite as Microscope, SCORER R. S., 1990, 268 pp. Ellis Horwood. New York, c37.50 hb, ISBN 13-79 1344-3.

OO?l-YlhYiY3$6.00+ 00 Pcrgamon Press Lid

Professor Scorer is a well-known figure in the fields of cloud physics and satellite meteorology. He has been responsible for a number of books on cloud classification and, more recently, on the capabilities of satellite observing systems to aid cloud investigations. As described in the Introduction, it was originally intended that this present book should have had the word ‘pollution’ in the title. However, this was dropped since the scope of the book increased during its preparation to encompass additional areas of cloud physics to deal fully with the central theme of the book which is the information on cloud and aerosol microphysical properties that can be deduced from the emitted and reflected signals received by Earth observation satellites. It is concerned pri- marily with the interpretation of imagery from the Advanced Very High Resolution Radiometer (AVHRR) on the U.S. TIROS-N/NOAA series of polar orbiting meteorological satellites, although some imagery from the Coastal Zone Color Scanner (CZCS) on Nimbus 7 is also included. The AVHRR instrument has a horizontal resolution of about 1 km and a swath width of 3ooO km making it ideal for cloud studies since the two instruments in orbit at any one time can provide coverage of any location on the Earth at least four times a day. The five channels in the visible and infra-red regions of the spectrum also provide a wealth of information when viewed singly or when the images are compared. Although the AVHRR was originally conceived as a meteorological instrument it soon proved valuable in many other fields including oceanography, land applications, crop monitoring and pollution investigations. The broad appli- cability of the imagery to environmental studies comes through in this book.

The early sections describe the spectral characteristics of the channels of the AVHRR and CZCS instruments and the interactions of radiation at these wavelengths with various types of surface and with atmospheric aerosol, haze and cloud. It is shown that the signals received by the instrument can depend on many factors including cloud droplet size, the relative angle of the Sun and satellite, cloud depth and sur- face properties. Perhaps the most interesting, and the most underused, channel on the AVHRR is that at 3.7 pm. There is a great deal of valuable information on interpreting these images which, at various times, include both emitted ter- restrial and reflected solar radiation. Although often appear- ing strange at first sight, which is presumably why they have had little use operationally, they are shown to contain more information than any other single channel provided that the user understands the processes affecting radiation at this wavelength.

The remainder of the book is concerned with the under- standing of various atmospheric phenomena through the interpretation of satellite imagery. There are chapters on plumes over the land and ocean, high altitude cloud gen- erated by mountains and aircraft, haze and other aerosols. deposition of pollution and newly discovered cloud forms. Each contains many satellite pictures with accompanying text and the author frequently provides detailed explanations of how he interprets the images.

The book is written in Professor Scorer’s robust, no-

14X8 Book reviews

nonsense style that we have come to know from earlier works. He obviously has little time for those who manipulate and combine the data on computer systems while lacking a basic knowledge of the cloud physics. This book is therefore not for those looking to develop empirical algorithms from sat- ellite data. Rather it provides a thorough grounding in the aspects of cloud physics and radiation theory relevant to interpreting visible and infra-red satellite pictures. It can be recommended wholeheartedly to researchers in satellite meteorology, pollution and tropospheric physics as well as weather forecasters who want to make better USC of the imagery that is available routinely.

J. TURNER British Antarctic Survey, Cambridge

Physics of the Outer Heliosphere, Cospar Colloquia Series Vol. I, GKZEDZIEISKI S. and PAGE D. E. (eds). 1990. 408 pp. Pergamon Press, Oxford, &50 hb, ISBN O-08040-780-3.

This book records the contributions to the COSPAR meeting held at Warszawa between 19 and 22 September 1989. In the last few years, several spacecraft, having passed the orbits of the outer planets, carried out in-G/u investigations of the solar wind at large distances. In the immediate future. the shock transition of the solar wind from supersonic to sub- sonic flow will be observed and the outer heliosphere will be open to direct measurements. Many reports in the collection are concerned with the status of these deep space missions, but there are also valuable discussions of the theoretical background and the implications of the observations.

In more detail, the volume contains (after an introductory lecture on the historical development of our knowledge on the matter in question) about 65 papers. They are subdivided into six chapters, corresponding to the sessions of the sym- posium. The first contains some observational results on the structure of the (very) local interstellar medium (LISM), which counteracts the flow of matter from the Sun and thus is responsible for the limitation of the heliosphere, i.e. the realm of dominance of the solar wind. The most important problems in that respect are the more or less exact deter- mination of the speed and direction of the LISM (with respect to the Sun) and its density. as well as the strength and orientation of the interstellar magnetic field. They give a reasonable overview of what is known today.

In the second session. the main object is the interaction of UV radiation with the neutral component of the outer solar wind regime. The observations of scattering, especially in the Lyman-cc and -/l lines give important information on the behaviour of the mass flow close to the heliopause (the outer boundary of the solar system). As yet, no direct measure- ments are available, although there is some possibility that plasma noise generated at the heliopause may have been seen in spacecraft data.

Another aspect is highlighted in the third section, namely the generation and spectral characteristics of the so-called ‘anomalous’ cosmic ray component. This has been a matter ofmuch debate in the recent past. It is hoped that the detailed study of cosmic rays will ultimately lead to a better under- standing of the physics of the heliosphere and the geometric and physical structure of the heliopause. Here also, theor- etical achievements are discussed at length, in particular the question of whether the heliosphere and its geometry are stable. It is obvious that pulsations of the configuration as a whole will have a strong and possibly observable inlluence on the cosmic ray spectra ; several papers consider how to

recover information on the physics close to the heliopausc from these.

As mentioned above, there are some hints that plasma waves excited at the outer heliospheric shock, or even at the heliopause itself, might have been recorded by the instru- ments onboard the Pioneer spacecraft. This. and many other related questions. are the topic of the fourth part of the book. Here, some theoretical approaches are given which demonstrate the surprisingly complicated picture of the flow and magnetic fields,

The subject of the fifth chapter is what happens at the boundary of the LISM and solar wind, the heliopause itself. Clearly, the studies are mainly theoretical here, but never- theless much can be said with confidence. Included are, among others, a few papers on the plasmaawave interaction at the heliopause. most of them based on MHD theory. This is a very active field, and up to now there is no universal agreement on the correct description. The papers in this section consider some of the proposed ideas.

The sixth and last session is on spacecraft missions, their present situation and plans for the near future. There are also some other contributions included which are concerned with several side-phenomena.

In summary, the editors did a good job in preparing this volume (and the meeting itself). It can be recommended without hesitation for everybody who is interested in plasma physics or astronomy. In comparison to many other con- ference reports, it can be hoped to be of value for a relatively long time span, since some of the papers will prove to be of fundamental importance for future research.

H. J. FAHR

Institut fur Astrophysik. Universitiit Bonn. F.R.G.

Ozone Measuring Instruments for the Stratosphere, GRANT

W. B. (ed.), 1989, 538 pp. Optical Society of America, Washington. D.C., $77.00 pb, ISBN l-55752-043-9.

This helpful and worthwhile reference book is a must for those of us in the rapidly-growing field of ozone-layer research who are so often called upon to give opinions about the value of someone else’s measurements. The book is organized into brief reviews of instruments and techniques, followed by a selection of papers which describe them in greater detail. The introductions are mostly very good and simply written. Usually, the papers are those which first announced the technique, and the breadth of their selection is a tribute to the editor’s thoroughness. For example, Dob- son’s paper is not in common circulation, yet it is an excellent introduction to the philosophy of the instrument-it should be mandatory reading for anyone who will be using the Dobson spectrophotometer and we shall be making sure that all our new recruits read it. In those papers where in- sufficient detail is given (e.g. the Russian equivalent of the Dobson). the reader is rescued by the comprehensive sets of references.

The book is not without its faults. Some parts of the format could have been handled better, particularly the classification ofinstruments. This could be confusing to new- comers to the subject, and conflicts with the histories of instrument development that are wjell known to some of us. It might have been better to avoid any groupings and describe each instrument separately. Fortunately. there is a com- prehensive index.

Also, the book shows signs of haste during preparation in the large number of minor errors (for example, the acronyms