E. Brüche and A. Recknagel, Die Elektronengeräte.
(Prinzipien und Systematik). 1941, 447 pp., 597 figs.

(E. Brüche and A. Recknagel, Electronic Devices).

The authors regard the present book as a kind of sequel to the old monograph, well known to everyone, by Brüche and Scherzer, Geometrical Electron Optics, 1934 (Russian translation with additions—Lenizdat, 1943), which, because of the enormous development of this field of physical electronics, naturally requires further updating. The book under review differs, however, in its character from the earlier monograph chiefly in that it emphasizes not the examination of the further development of the general methods of electron optics, but rather the application of these methods to problems of designing various modern electronic devices. This is evident from the consideration of the contents of the book, which is divided into two large parts: 1) the motion of electrons from the technical point of view and 2) the structure of electronic devices.

The first—smaller—part of the book (pp. 1–145) begins (Chs. I and II) with a discussion of the known features of electron motion in various electric and magnetic fields from the standpoint of electron-optical analogies, including questions of focusing with respect to directions and phases. Then follows (Ch. III) an elementary exposition of electronic emission, an examination of electron-optical methods of use and control of electron beams, and of the role of the external circuit. Ch. IV considers the features of the application of electric and magnetic fields in electronic and electron-optical systems, the role of geometry and velocities in the beam, and certain features of the dynamic regime. Ch. V examines electron sources, elementary designs of electric and magnetic lenses, prisms, mirrors and diaphragms, methods of observing electron beams, their behavior in a rarefied gas, the cathodoluminescence caused by them, and their photographic action.

The second—larger—part of the book (pp. 146–422) begins with a systematics of electronic devices, which the authors divide into 5 categories, namely: 1) devices with variable intensity of the electron current, 2) Lenard and X-ray tubes, 3) electron-beam devices, 4) devices for obtaining images, and 5) spectral devices. According to this somewhat debatable classification, various electronic devices are considered here in Chs. VI–XI. Ch. VI deals, in an elementary way, with vacuum and gas-filled photocells, photomultipliers, counters and, finally, various electron tubes from diodes to multi-electrode and beam switching tubes inclusive. Ch. VII considers Lenard and X-ray tubes and certain sources of high voltage. Ch. VIII examines cathode oscillographs of various types and beam tubes for cathode television, as well as the functions of their individual elements. Ch. IX considers questions of electron microscopy, i.e. the elements of the construction of ordinary microscopes and ultramicroscopes and some of their practical applications; it is strange here that in this chapter, very awkwardly, an entire section has been inserted devoted to electron-optical image converters (10 pp. and 20 figs.). Ch. X examines a very important group of questions devoted to high-frequency devices, where the essential role is played by the electron transit time: the features of electron deflection in high-frequency fields and lenses, measurement of velocities with ta

chemical instruments, high-frequency accelerators and multipliers, and certain methods of exciting oscillations. Finally, Ch. XI considers general methods of spectroscopy of corpuscular rays, focusing according to directions and velocities, and designs of certain modern mass spectrographs.

Turning to the characterization of this book, it must first of all be pointed out that the presentation of the material is somewhat popular and not very profound, and is chiefly descriptive in character; in this sense it is, on the whole, very close in style to the second part (Applications, Chs. V–VII) of the old monograph by Brüche and Scherzer. One may regretfully note that the authors, as a rule, do not go very deeply into the consideration of the questions they set forth; that almost all calculation formulas are usually given without derivation, in final and not always obvious form, and so on. The book has the character of a small encyclopedia on this very broad problem and, incidentally, contains a very detailed (754 titles) index of the original literature. Nevertheless, despite all the foregoing, the book is read with considerable interest, since the presentation of the material is very fresh and original in conception: here, for the first time, a systematic consideration of modern electronic devices is conducted from the standpoint of methods of electron optics which, though by now no longer very new, are nevertheless highly promising and distinctive; the authors themselves made a very substantial contribution to their creation. It should be noted that such an approach—convenient, very interesting, and important—to the analysis of processes in electronic devices is usually little used in most modern textbooks and monographs on this subject, which is undoubtedly a considerable shortcoming. Therefore the example of this book once again emphasizes the pressing necessity for the wide introduction of the electron-optical method of analyzing physical processes in modern electronic devices, which will inevitably lead to their more complete understanding, use, and further improvement.

N. D. Morgulis