Chronicle

The Laboratory of Electromagnetism at the Faculty of Physics of Moscow State University

(On the 30th Anniversary of Its Founding)

In April of this year it will be 30 years since the establishment of the Laboratory of Electromagnetism, founded and continuously headed by a pupil of P. N. Lebedev, Corresponding Member of the Academy of Sciences of the USSR, Prof. V. K. Arkadiev.

The activity of the Laboratory was directed chiefly toward an in-depth elaboration and further development of Prof. V. K. Arkadiev’s investigations carried out by him in 1908–1914. These include the discovery of the disappearance of the magnetic properties of ferromagnetic metals in high-frequency fields (in centimeter waves), the broadening of the concept of “magnetic permeability” by introducing the concept of “complex magnetic permeability” on the basis of the dependence, experimentally established by V. K. Arkadiev, of the latter on the length of electromagnetic waves, and the introduction of the concept of “magnetic conductivity” and the resulting generalization of Maxwell’s equations by introducing into them an added term for the case of sinusoidal processes. In connection with this, the dependence of the propagation of electromagnetic waves (their dispersion and absorption) on the microstructure of a ferromagnetic metal and on the time of the intrinsic oscillations of molecular magnets was clarified. Thus a theory of electromagnetic phenomena in ferromagnetic metals was created, and at the same time the first theory of magnetic resonance, which now bears the name “nuclear magnetic resonance.”

The development of these works by the Laboratory of Electromagnetism resulted above all in Prof. V. K. Arkadiev’s detailed elaboration of the theory of the electromagnetic field, which made it possible to study and theoretically illuminate electromagnetic processes in metals, predominantly in ferromagnetic ones; to provide methods for the analytical and graphical determination of magnetic permeability for various cases, especially as a function of the frequency of the external magnetic field; and to build on this basis a theory of magnetic spectra, creating a new extensive section of the theory of magnetism—magnetodynamics, which studies the magnetization of metals in the nonstationary state (as a function of time).

Prof. V. K. Arkadiev’s works opened the way to consideration of various questions of theoretical electrical engineering on the basis of the general theory of the electromagnetic field; they outlined new ways of studying superconductivity at low temperatures, etc. In particular, the study of the skin effect led to the discovery of the interaction of a moving magnetic field and a superconductor—an interaction that made it possible to find a new phenomenon: the levitation of a magnet in space above a superconductor—

...opened a new type of equilibrium of bodies in world space, in the indicated case of the “Earth—Magnet” system. These works made it possible experimentally to demonstrate the law of constancy of the magnetic flux (the law of Mitkevich), to begin the development of the design of a magnetic compressor, etc. Along with this, it became possible to solve certain practical problems of electrical engineering (saving copper), apparatus construction (radio engineering, telephony, telegraphy, etc.), or to indicate paths toward their solution. The determination of magnetic-field strength in measurements of permeability at ultrahigh frequencies required observations of the electric spark that served to obtain short radio waves, which led to the determination of discharge potentials at high frequency, and further, to the discovery of the unexpected fact that oscillations of small Hertz vibrators, along with damped waves, also produce undamped centimeter waves. This may have application in radio engineering even at the present time, provided that the corresponding constructive forms of these vibrators are developed.

The construction of a mass emitter of short waves, theoretically developed in 1914 by V. K. Arkad’ev and practically realized by A. A. Glagoleva-Arkad’eva, made it possible to fill an existing gap in the electromagnetic spectrum; this interval of wavelengths (6.0–0.343 mm), not long before yielded especially to physicists, was considerably overlapped in 1922, since with the aid of the mass emitter waves with lengths from 50 to 0.082 mm were obtained. Thus the unity of the electromagnetic nature of radio waves and light waves was definitively proved, and at the same time it became possible to complete the construction of the scale of electromagnetic waves. Microwaves were used in the Laboratory as a new means for studying the homogeneity of the structure of bodies and for detecting foreign inclusions. Developing the analogy between light waves and Hertzian waves, Prof. V. K. Arkad’ev came to the idea of the possibility of recording the latter on a correspondingly sensitive plate, and in 1934 experimentally confirmed this idea: on special photographic paper Hertz waves were recorded in the form of more or less dense accumulations of small spots. Thus was laid the beginning of a new method of physical investigation—stictography, which opened broad prospects for transferring methods of photography into radio engineering, for transillumination in those cases when X-rays prove powerless: to detect foreign inclusions in semiconductors and dielectrics. At present, magnetic resonance, spark excitation of undamped microwaves, and stictography are being widely developed both in our country and abroad.

The achievements of the Laboratory of Electromagnetism are set forth in the work of Prof. V. K. Arkad’ev, Electromagnetic Processes in Metals (Part I, 1935, and Part II, 1936), as well as in the collections published under his editorship: Contemporary Problems of Electromagnetism (1931), Problems of Electrotechnical Metal (1938), Practical Problems of Electromagnetism (1939), Problems of Ferromagnetism and Magnetodynamics (1946), in Collected Works of A. A. Glagoleva-Arkad’eva (1948), and in numerous articles published both in domestic and foreign journals.

At the present time the Laboratory of Electromagnetism faces the tasks of the further development and practical use of the theory of magnetic spectra, the development of technical conditions for obtaining the most perfect magnetic insulating materials in communications technology, the manufacture of the technical design of a mass emitter, the improvement of methods of stictography, the detailed study of the question of spark excitation of undamped oscillations, etc. Prof. V. K. Arkad’ev, under whose direction the Laboratory has achieved such...

major results, continues tirelessly to work in the Laboratory he created and is preparing the second, expanded edition of his work Electromagnetic Processes in Matter, which constitutes a systematic summary and generalization of the numerous results obtained in the Laboratory, and a vivid illustration of the achievements of Russian science.

N. D. Shostak