Frequency-lock system for microwave local oscillators using molecular absorption lines

We describe the frequency-lock (FL) system for local oscillators in receivers in the 130 to 360 GHz range, using the resonance lines of molecules with a known absorption spectrum. The functions of a frequency discriminator, a diplexer, and a noise rejector are performed by a Mach-Zehnder interferometer with a gas cell. Deceased Institute of Applied Physics of the Russian Academy of Sciences, Nizhny Novgorod, Russia. Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Radiofizika, Vol. 41, No. 11, pp. 1399–1404, November, 1998.     

Dissociation of water by microwave radiation

The hydrogen-peroxide concentrations c(H₂O₂) in water irradiated by electromagnetic energy at frequencies of 2500 MHz and 10000 MHz are measured by means of chemiluminescence. It is concluded that water dissociation into H and OH groups is a part of the mechanism of microwave-radiation absorption.Institute of Applied Physics, Russian Academy of Sciences. Institute of Organometallic Chemistry, Russian Academy of Sciences. Translated from izvestiya Vysshikh Uchebnykh Zavedenii, Radiofizika, Vol. 37, No. 1, pp. 149–154, January, 1994.     

Transformation of a single-pulse echo into a two-pulse one upon change in excitation pulse form

Physics Institute, Siberian Branch, Russian Academy of Sciences. Applied Physics Problems Scientific-Research Institute, Belorussian University. Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Radiofizika, Vol. 35, No. 1, pp. 96–98, January, 1992.     

Effect of nonsinusoidal phase modulation on the zero shift in a fiber ring interferometer

Institute of Applied Physics, Russian Academy of Sciences. Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Radiofizika, No. 10, pp. 1345–1349, October, 1994.     

Development of a phase-lock system up to terahertz frequencies in microwave oscillators

The development of a phase-lock system up to the highest frequencies greater than one terahertz in microwave oscillators is considered. Applications of such systems for physical and technical measurements are discussed. Institute of Applied Physics of the Russian Academy of Sciences, Nizhny Novgorod, Russia. Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Radiofizika, Vol. 41, No. 11, pp. 1361–1377, November, 1998.     

High-Harmonic Gyrotrons with Axis-Encircling Electron Beams at IAP RAS

Radiophysics and Quantum Electronics - The Institute of Applied Physics of the Russian Academy of Sciences has for many years been developing sub-terahertz and terahertz large-orbit gyrotrons that...     

Waves,waves, and more waves

Institute of Applied Physics, Russian Academy of Sciences. Edited from Izvetiya Vysshikh Uchebnykh Zavedenii, Radiofizika, Vol. 36, No. 7, pp. 576–587, July, 1993.     

Space plasma under extreme conditions

Attributes of extreme conditions in space and the new properties which plasma acquires in this case are discussed. The discussion is focussed on the features of interaction between plasma and radiation in strong magnetic fields of degenerate stars—white dwarfs or neutron stars. The specific role of cyclotron scattering, radiation pressure at cyclotron frequencies, and vacuum birefringence in the formation of plasma envelopes and the observed spectra of these objects is pointed out. The contents of this paper provided the basis for the report at the scientific session of the General Physics and Astronomy Division of the Russian Academy of Sciences devoted to the eightieth anniversary of Vitaly L. Ginzburg. Institute of Applied Physics, Russian Academy of Sciences, Nizhny Novgorod; Max Plank Institut für Extraterrestrische Physik, Garching, Germany. Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Radiofizika, Vol. 40, Nos. 1–2, pp. 17–36, January–February, 1997.     

Boundary-wave transfer of field energy through supercritical regions of waveguides

Institute of Applied Physics, Russian Academy of Sciences. Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Radiofizika, Vol. 35, No. 2, pp. 171–176, February, 1992.     

Wave-beam passage through dielectric plate

Institute of Applied Physics, Russian Academy of Sciences. Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Radiofizika, Vol. 37, No. 4, pp. 535–538, April, 1994.     

Statistical properties of the acoustic field of a moving source in a random inhomogeneous medium in the presence of a rough boundary

Institute of Applied Physics, Russian Academy of Sciences, Nizhegorodskii State University. Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Radiofizika, Vol. 35, No. 2, pp. 161–170, February, 1992.     

Suppression of coupling between orthogonally polarized modes in weakly anisotropic light guides when winding fiber

Institute of Applied Physics, Russian Academy of Sciences, Nizhny Novgorod. Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Radiofizika, Vol. 38, No. 6, pp. 604–607, June, 1995.     

A decade of optical coherence tomography in Russia: From experiment to clinical practice

We give a retrospective review of studies performed by a joint team of researchers from the Institute of Applied Physics of the Russian Academy of Sciences and the Nizhny Novgorod State Medical Academy and related to practical implementation of optical coherence tomography and its use as a novel method for biomedical diagnostics.     

The role of excited species in UV-laser materials ablation

UV-laser ablation is described in terms of a two-level system in which the excitation energy is dissipated via stimulated emission, thermal relaxation, and activated desorption of excited species. For thermal relaxation times t _T>10^–9 s and E* E (activation energies for excited-state and ground-state species) the model predicts high ablation rates at moderate surface temperatures, typically below 2000° C.On leave from General Physics Institute, Russian Academy of Sciences, 117942 Moscow, RussiaOn leave from Institute of Applied Physics, Russian Academy of Sciences, 603600 Nizhnii Novgorod, RussiaOn leave from L.D. Landau Theoretical Physics Institute, Russian Academy of Sciences, 142432 Chernogolovka, Moscow region, Russia     

Clear-air millimeter-wave scattering

Clear-air millimeter-wave backscattering is observed experimentally by means of a high-power gyrotron generator and a superheterodyne receiver.Institute of Applied Physics, Russian Academy of Sciences. Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Radiofizika, Vol. 36, No. 10, pp. 942–944, October, 1993.     

Interferential algorithm for ocean bottom diagnostics

The efficiency of determining sound velocity, sound density, and acoustic attenuation factor in the bottom is evaluated by a numerical experiment, using the method of interferential ocean bottom tomography proposed by the authors. Simulation is performed in the presence of random noise when the source power is unknown.Deceased.Institute of Applied Physics, Russian Academy of Sciences, Nizhny Novgorod. Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Radiofizika, Vol. 38, Nos. 3–4, pp. 202–205, March–April, 1995.     

Gas-filled position-sensitive detectors of thermal neutrons at the Konstantinov Petersburg Nuclear Physics Institute of the Russian Academy of Sciences

The manufacturing line for the development and fabrication of position-sensitive detectors of thermal neutrons has been organized at the Petersburg Nuclear Physics Institute of the Russian Academy of Sciences. Three detectors with sensitive regions 300 × 170 (prototype), 200 × 200, and 300 × 300 mm in size have been constructed to date. The detectors represent multiwire proportional chambers with cathode data readout to a delay line. The devices are filled with the ³He/CF₄ gas mixture. These detectors are intended for modernizing the detector systems of the Vector and Membrana-2 diffractometers (VVR-M reactor, Konstantinov Petersburg Nuclear Physics Institute of the Russian Academy of Sciences, Gatchina, Russia).     

Application of a mobile seismoacoustic system for studying geological structure and prospecting for inhomogeneities to a depth of 100 m

The results of a practical evaluation of a mobile seismoacoustic system intended for the search for underground engineering structures and their imaging are presented. The system was designed at the Institute of Applied Physics of the Russian Academy of Sciences and consists of an electrodynamic radiator of seismoacoustic waves that operates in the frequency range 200–800 Hz, an array of receivers, and a computer-based control unit. The signal is controlled digitally, which allows the system to store up to 10³ realizations. The signal is received by high-sensitivity seismic sensors, amplified by low-noise amplifiers, supplied to a 16-channel A/D converter, and displayed on the computer monitor. The system was used in a field experiment to determine the location of an antilandslide drainage adit.     

On the transmittance of the polar atmosphere for millimeter radioastronomy

We discuss the discrepancy between experimental and calculated values of attenuation in water vapor, which is observed for a sufficiently low tropospheric temperature (of the order of −30°C). We indicate the high correlation of excessive attenuation with the quadratic component of tropospheric humidity. Institute of Applied Physics, Russian Academy of Sciences, Nizhny Novgorod, Russia. Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Radiofizika, Vol. 40, No. 12, pp. 1479–1488, December, 1997.