All-Russian Scientific Research Institute of Physical-Technical and Radiotechnical Measurements

The numerical values of the van der Waals interaction constant C6 are determined between alkaline earth atoms in singlet Rydberg |n1S0〉 states with large principal quantum numbers, n > 20. The results of calculations using the semiempirical quantum defect theory (QDT) method are approximated by quadratic polynomials. The polynomial coefficients are tabulated and can be used for simplified quantitative estimates of interatomic interaction-induced energy shifts, determination of the Rydberg state excitation blockade radius, and limitations on the wavelengths of radiation forming Rydberg lattices for group IIA atoms. The numerical values of the contributions of various diatomic states to the constant C6 are calculated. States providing the main contribution, analogous to that of the Förster resonance, are identified.

This work presents a description of the software (SW) developed for a test bench designed to study the high-precision relative gravimeter "Peshekhod" using the tilting method. The software fully automates the measurement cycle: controlling the actuators to tilt the platform according to a specified algorithm, synchronous data acquisition from the gravimeter and inclinometer, and subsequent mathematical processing. Two methods for determining the gravimeter's sensitivity axis position are discussed in detail: the classical two-parabola method and an advanced paraboloid method developed to account for cross-coupling during tilts in different planes. Data processing employs the least squares method (LSM) to accurately determine the sensitivity axis coordinates. Experimental testing demonstrated that the paraboloid method refines the sensitivity axis position by approximately 16″ compared to the two-parabola method. The developed software proves to be an effective tool for the precise adjustment of the "Peshekhod" gravimeter.

The article discusses a field geophysical complex that includes the Earth's gravity and magnetic fields parameters meters — an digital zenith camera (DZC), a relative gravimeter, onboard quantum magnetometer and ground magnetovariation station. This complex allows determining such parameters of the Earth's gravity field as acceleration and anomalies of gravity, plumb line deviations, horizontal components of the acceleration of gravity and gravitational gradients, and parameters of the Earth's magnetic field — absolute and anomalous values of induction. Maps of the Earth's gravity and magnetic fields can be used in various fields, in particular, in the creation and testing of integrated autonomous navigation systems using the parameters of these fields. The paper presents examples of parameter maps created using this complex. The measurement error of acceleration and gravity anomaly is 10 µGal, plumb line deviation is ≈ 0.2″, horizontal components of gravity acceleration are ≈ 1 mGal, gravitational gradients are 10 Eötvös at a distanc

Abstract The author proves that many inhomogeneous plasma structures with characteristic sizes from 10−15 to 1026 m are formed (in plasma with current) by convective cumulative and dissipative processes. Electrical phenomena are observed in non-uniform atmospheres and ionospheres of all planets of the Solar System. The author has constructed for the first time the most complete non-stationary nonlinear 4D perturbation theory for describing the nonlinear interaction of a non-uniform plasma with current with an electric field. A modified non-stationary Navier-Stokes 4D equation for the electron concentration is obtained (with the violation of plasma electroneutrality in the approximation of small ion current compared to electron current) and its quasi-stationary solution is visualized, describing Vysikaylo’s plasma nozzles (analogue of Laval’s nozzles) and Vysikaylo’s shock waves (electric field). The work is of scientific and practical interest for interdisciplinary research and the development of a method for transfer of mathematical models from some areas of physical sciences to others, where their development is not yet sufficiently complete. This work is of interest to researchers of nonlinear 4D self-organization of plasma in the electric field of cumulative-dissipative structures in semiconductors, plasma in gas discharges, the ionosphere of the Earth and other planets, the heliosphere, stellar spheres, lightning, intergalactic lightning, etc.

The spectrum of the high harmonics generated by a Ga+ ion exposed to an intense femtosecond laser pulse simultaneously with short-wavelength radiation whose frequency is multiple of the fundamental harmonic and intensity is much lower than the laser intensity has been theoretically investigated. The calculation results show significant enhancement of the radiation of the odd harmonic that is in a multiphoton resonance with the transition from the ion ground state to the autoionizing state 3d94s24p 1P1 and single-photon resonance for the short-wavelength radiation with an increase in its intensity to 109 W/cm2. The effect of the enhancement due to the single-photon resonant pump may explain the resonant enhancement of the harmonic observed in experiments with a gallium plasma target.

The results of the investigations of the waveguide precision thermoelectric power sensors in the mode of the continuous automatic substitution of the microwave power by the Direct Current power are presented. The results were obtained by measurements in a microcalorimeter and by the method of comparison with the standard bolometric power sensors.

The paper considers the possibility of constructing a device for a acceleration measurement based on an optical interferometer instead of a capacitive measuring system. The design of polarization single-frequency interferometer is considered. The layout of the accelerometer sensing element and a bench for measuring its sensitivity are also described. The results of the study are presented and prove the possibility of achieving sensitivity not worse than $10^{-8} \mathrm{~m} / \mathrm{s}^{2}$.

We report on the operation of the cesium fountain primary frequency standard (SU-CsFO2), the rubidium fountain frequency standard (Rb5) and the pair of rubidium frequency standards (Rb1, Rb2) at the Russian metrological institute of technical physics and radio engineering (VNIIFTRI (SU)). We present measurements of their performance in long term frequency stability to be less than 2·10<sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">−16</sup>. The frequency of SU-CsFO2 with total B uncertainty 2.2·10<sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">−16</sup> agreed well with other primary and secondary frequency standards within the uncertainty according to the Circular T data during the last 10 years.