Vol 193, No 10 (2023)

We review the development of modern models of the magnetic field of Earth's inner magnetosphere, from the selection of experimental results to the approximation and presentation of the model output data. In particular, we discuss all principal sources of the magnetic field, their description in various models, and approaches to parameterizing the field. We briefly recall the history of the study of Earth's magnetic field and discuss modern-day and earlier experimental data used in model building and the underlying core mathematical tools. The main features of the majority of modern models describing Earth's magnetic field in the inner magnetosphere are discussed.

The operating principles and capabilities of X-ray grating interferometry are described using Talbot and Talbot–Lau interferometers as examples. Various types of diffraction gratings and methods for their production are described. Methods for collecting data in radiography and computed tomography, the origin of artifacts in X-ray images, and methods of suppressing them are considered. Particular attention is devoted to dark-field X-ray imaging and its application in medicine.

A solemn meeting (scientific session) of the Physical Sciences Division (PSD) and the Nanotechnology Division of the Russian Academy of Sciences (RAS), as well as the Scientific Councils of the P N Lebedev Physical Institute (LPI) RAS and the A M Prokhorov General Physics Institute (GPI) RAS, On the 100th Anniversary of the Birth of N G Basov: the ‘BASOV READINGS,’ was held in the Assembly Hall of the P N Lebedev Physical Institute on November 28, 2022.Opening remarks were made by:Kolachevsky N N (LPI), Kveder V V (PSD RAS), Garnov S V (GPI RAS)The scientific program of the joint meeting, published on the website of the PSD RAS (http://www.gpad.ac.ru), included the following reports and speeches:Session 1. Chair: Academician G A Mesyats1. Zubarev I G (LPI, National Research Nuclear University (NRNU) Moscow Engineering Physics Institute (MEPhI), Moscow). N G Basov: a pioneer and organizer of laser research in the USSR.2. Kolachevsky N N (LPI, Moscow). From the first masers to optical frequency standards.3. Pikhtin N A (A F Ioffe Physico-Technical Institute (PTI) RAS, St. Petersburg). High-power near-IR laser diodes: history, state of the art, and development prospects.4. Konov V I (Natural Science Research Center, GPI RAS, Moscow). Modern micro- and nanotechnologies of laser processing of materials.Session 2. Chair: Academician I A Shcherbakov5. Gus'kov S Yu (LPI, Moscow). N G Basov: laser thermonuclear fusion and high energy density physics.6. Mikaelyan G T (LASSARD LLC, NPP Inzhekt LLC, Moscow). One- and two-D diode laser arrays. Technology of production and application.7. Starodubtsev M V (FRC Institute of Applied Physics RAS, Nizhny Novgorod). Research in the field of plasma physics and particle acceleration with the PEARL petawatt laser.8. Evtikhiev N N (STA IRE Polyus, NRNU MEPhI, Moscow). On the application of laser technologies in industry and medicine.9. El'tsov K N (GPI RAS). Surface physics for heterogeneous catalysis, quantum computing, and two-dimensional materials.10. Zvorykin V D (LPI, Moscow). \textit{N G Basov's role in work on excimer laser research: a half-century history from the launch of the first $ Xe{_2}$ laser at the LPI to modern laser systems.}For the 100th anniversary of N G Basov's birth, scientific and biographical materials were published in the journal Uspekhi Fizicheskikh Nauk (UFN) (see Refs [1–3]), as was a special issue of the journal Quantum Electronics (QE) [4]. Papers written on the basis of reports 1, 3, and 5 were published in QE (see [5–7]), and those written on the basis of reports 2 and 10 are published below in this issue of UFN (see [8, 9]).

In a review dedicated to the 100th anniversary of the birth of academician N G Basov, the fate of one of his scientific predictions is traced: obtaining lasing at bound-free transitions of liquid xenon. Launched at the Lebedev Physical Institute (LPI) of the Academy of Sciences of the USSR in 1970, the $ Xe_2$ laser pumped by an electron beam marked a new dimension in laser physics: the advent of high-power excimer lasers generating radiation in the range from visible to vacuum ultraviolet. The main types and excitation methods of excimer lasers and the properties of their gain medium are considered. The most powerful pulsed excimer laser systems designed for laser thermonuclear fusion and amplification of UV multiterawatt ultrashort pulses are described, as well as repetition-rate lasers for applications in medicine, microelectronics, material processing, etc.

Progress in the generation of extremely short pulses of electromagnetic radiation makes the question of the properties of the limiting form of their shortening—unipolar pulses with a significant zero-frequency component of the spectrum, that is, the electric area of the pulse—relevant. Recently, it has been established that it is the electric area that determines the effectiveness of the impact of extremely short pulses on micro-objects. At the same time, unipolar pulses have a number of unusual properties, which makes some researchers doubt the possibility of their existence and propagation. Here, we show that a uniformly moving relativistic electric charge creates a short unipolar pulse of the electromagnetic field. Unipolarity is realized as well for transition radiation. We also present the unipolarity condition for a pair of charges—a dipole—and for a more general system of moving charges. This confirms the reality of unipolar electromagnetic pulses, which are promising for applications of extremely short pulses.