We present new orbital solutions for 15 binaries, which were astrometrically measured by our team during 2010–2013, using the FastCam ‘lucky-imaging’ camera installed at the 1.5-m Carlos Sánchez Telescope (CST) at the Observatorio del Teide, Tenerife (Spain). We present first orbital solutions for BU 1292, STF 147, HDS 1898, and STT 325 and revise orbital solutions for AG 14, D 5 AB, A 1581, HO 525 AB, WOR 19, A 1999, HU 572, HU 742, COU 227, BU 696 AB, and A 893. We apply two orbital calculation techniques, the ‘three-dimensional grid search method’, first described by Hartkopf, McAlister, & Franz (1989), and the Docobo’s analytical method (Docobo 1985). We use our tool ‘Binary Deblending’, based on deblending the entire observed multiband photometry into fundamental and photometric parameters for each stellar component based on PARSEC isochrones. We also obatain the total mass for all systems. Our findings include the identification of a binary system consisting of two M-type dwarfs (WOR 19), a binary of evolved components (twin F6IV-V stars) in BU 1292, accompanied by a newly discovered wide (10.5") and faint companion with G = 17.05 mag. Additionally, we explore the X-ray emission system STF 147 and a very young quadruple system, WDS 04573+5345. This comprehensive analysis significantly contributes to our understanding of the formation and evolution of stellar systems.

We are showing a significant enhancement in the temporal contrast by reducing the coherent noise of the 10 PW laser system at the Extreme Light Infrastructure - Nuclear Physics facility. The temporal contrast was improved by four orders of magnitude at 10 picoseconds and by more than one order of magnitude at 50 picoseconds before the main peak. This improvement of the picosecond contrast is critical for the experiments using thin solid targets.

The emerging era of big data in radio astronomy demands more efficient and higher-quality processing of observational data. While deep learning methods have been applied to tasks such as automatic radio frequency interference (RFI) detection, these methods often face limitations, including dependence on training data and poor generalisation, which are also common issues in other deep learning applications within astronomy. In this study, we investigate the use of the open-source image recognition and segmentation model, Segment Anything Model (SAM), and its optimised version, HQ-SAM, due to their impressive generalisation capabilities. We evaluate these models across various tasks, including RFI detection and solar radio burst (SRB) identification. For RFI detection, HQ-SAM (SAM) shows performance that is comparable to or even superior to the SumThreshold method, especially with large-area broadband RFI data. In the search for SRBs, HQ-SAM demonstrates strong recognition abilities for Type II and Type III bursts. Overall, with its impressive generalisation capability, SAM (HQ-SAM) can be a promising candidate for further optimisation and application in RFI and event detection tasks in radio astronomy.

In this paper, we prove that the third near-infrared (NIR-III) window high-power laser with wavelength in the range of 1600–1800 nm can be obtained by the coherent Raman fiber amplification technique through theoretical and experimental study. Detailed numerical simulation reveals that the nonlinear dynamics of the Raman fiber amplification in the polarization-maintaining double-clad erbium-ytterbium co-doped fiber is similar to that of the Mamyshev oscillator. Through the spectral filtering effect induced by finite Raman gain, we can obtain a high-quality Raman pulse. According to the theoretical results, we design a simple Raman fiber amplification laser and finally obtain a high-quality watt-level NIR-III window laser pulse in which the central wavelength is about 1650 nm and the pulse width can reach 85 fs. The experimental results correspond to the simulation results. Such nonlinear effect is universal in all kinds of fibers, and we think this technology can provide a great contribution to the development of ultrafast fiber lasers.

Since August 2014, a monitoring survey at a frequency of 111 MHz has been conducted on the Large Phased Array (LPA) radio telescope of the P.N. Lebedev Physical Institute (LPI). We report the discovery of a bright pulse having a dispersion measure (DM) equal to $134.4\pm2\ \text{pc cm}^{-3}$, a peak flux density ($S_p$) equal to $20\pm4$ Jy, and a half-width ($W_e$) equal to $211\pm6$ ms. The excessive DM of the pulse, after taking into account the Milky Way contribution, is $114\ \text{pc cm}^{-3}$ that indicates its extragalactic origin. Such value of DM corresponds to the luminosity distance 713 Mpc. The above parameters make the pulse to be a reliable candidate to the fast radio burst (FRB) event, and then it is the second FRB detected at such a large $\lambda\sim2.7$ m wavelength and the first one among non-repeating FRBs. The normalised luminosity $L_\nu$ of the event, which we have designated as FRB 20190203, estimated under assumption that the whole excessive DM is determined by the intergalactic environment towards the host galaxy, is equal to $\simeq 10^{34}\ \text{erg s}^{-1} \text{Hz}^{-1}$. In addition to the study of radio data we analysed data from the quasi-simultaneous observations of the sky in the high energy ($\geq 80$ keV) band by the omnidirectional detector SPI/ACS aboard the INTEGRAL orbital observatory (in order to look for a possible gamma-ray counterpart of FRB 20190203). We did not detect any transient events exceeding the background at a statistically significant level. In the INTEGRAL archive, the FRB 20190203 localisation region has been observed many times with a total exposure of $\sim 73.2$ days. We have analysed the data but were unable to find any reliable short gamma-ray bursts from the FRB 20190203 position. Finally, we note that the observed properties of FRB 20190203 can be reproduced well in the framework of a maser synchrotron model operating in the far reverse shock (at a distance of $\sim 10^{15}$ cm) of a magnetar. However, triggering the burst requires a high conversion efficiency (at the level of 1%) of the shock wave energy into the radio emission.

This paper presents a theoretical model of plasma equilibrium in the diamagnetic confinement mode in an axisymmetric mirror device with neutral beam injection. The hot ionic component is described within the framework of the kinetic theory, since the Larmor radius of the injected ions appears to be comparable to or even larger than the characteristic scale of the magnetic field inhomogeneity. The electron drag of the hot ions is taken into account, while the angular scattering of the hot ions due to Coulomb collisions is neglected. The background warm plasma, on the contrary, is considered to be in local thermal equilibrium, i.e. has a Maxwellian distribution function and is described in terms of magnetohydrodynamics. The density of the hot ions is assumed to be negligible compared with that of the warm plasma. Both the conventional gas-dynamic loss and the non-adiabatic loss specific to the diamagnetic confinement mode are taken into account. In this work, we do not consider the effects of the warm plasma rotation as well as the inhomogeneity of the electrostatic potential. A self-consistent theoretical model of the plasma equilibrium is constructed. In the case of the cylindrical bubble, this model is reduced to a simpler one. The numerical solutions in the limit of a thin transition layer of the diamagnetic bubble are found. Examples of the equilibria corresponding to the gas-dynamic multiple-mirror trap device are considered.

An ionized gas medium (plasma state) turns to a complex state of plasma or dusty plasma if micrometre- to submicrometre-sized solid dust particles are introduced in it. The dusty plasma medium exhibits fluid- as well as solid-like characteristics at different background plasma conditions. It supports various linear and nonlinear dynamical structures because of external perturbation and internal instabilities. The vortical or coherent structure in the dusty plasma medium is a kind of self-sustained dynamical structure that is formed either by instabilities or by external forcing. In this review article, the author discusses the past theoretical, experimental and computational investigations on vortical and coherent structures in unmagnetized and magnetized dusty plasmas. The possible mechanisms of the formation of vortices in a dust-grain medium are discussed in detail. The studies on the evolution of vortices and their correlation with turbulence are also reviewed.

This study investigates the impact of local thermal non-equilibrium on the stability analysis of partially ionized plasma within a porous medium. The plasma, heated from below, is enclosed by various combinations of bounding surfaces. Both nonlinear (via the energy method) and linear (utilizing the normal mode analysis method) analyses are performed. Eigenvalue problems for both analyses are formulated and solved using the Galerkin method. The study also explores the effects of compressibility, medium permeability and magnetic fields on system stability. The collisional frequency among plasma components and the thermal diffusivity ratio significantly influence energy decay. The results reveal that the Rayleigh–Darcy number is identical for both nonlinear and linear analyses, thus eliminating the possibility of a subcritical region and confirming global stability. The principle of exchange of stabilities is validated, indicating the absence of oscillatory convection modes. Medium permeability, heat-transfer coefficient and compressibility delay the onset of convection, demonstrating stabilizing effects. Conversely, the porosity-modified conductivity ratio hastens the convection process, indicating destabilizing effects. Rigid–rigid bounding surfaces are found to be thermally more stable for confining the partially ionized plasma. Additionally, the magnetic field exerts a stabilizing influence.

Kinetic theory of particles near resonances is a current topic of discussion in plasma physics and astrophysics. We extend this discussion to the kinetic theory of the interaction between alpha particles (energetic particles predicted to exist in large quantities in next-generation fusion experiments) and a neoclassical tearing mode (NTM), a resistively-driven perturbation which sometimes exists in a tokamak. We develop a quasilinear treatment of the interaction between alpha particles and an NTM, showing why an NTM can be a source of significant passing alpha particle transport in tokamaks. The limitations on quasilinear theory constrain our theory's applicability to small amplitude NTMs, highlighting the importance of nonlinear studies.

It is common wisdom that collisionless shocks become non-planar and non-stationary at sufficiently high Mach numbers. Whatever the shock structure, the upstream and downstream fluxes of the mass, momentum and energy should be equal. At low Mach numbers, these conservation laws are satisfied when the shock front is planar and stationary. When this becomes impossible, inhomogeneity and time dependence, presumably in the form of rippling, develop. In this study, we show that the shock structure changes as a kind of ‘phase transition’ when the Mach number is increased while other shock parameters are kept constant.

For the pulse shaping system of the SG-II-up facility, we propose a U-shaped convolutional neural network that integrates multi-scale feature extraction capabilities, an attention mechanism and long short-term memory units, which effectively facilitates real-time denoising of diverse shaping pulses. We train the model using simulated datasets and evaluate it on both the simulated and experimental temporal waveforms. During the evaluation of simulated waveforms, we achieve high-precision denoising, resulting in great performance for temporal waveforms with frequency modulation-to-amplitude modulation conversion (FM-to-AM) exceeding 50%, exceedingly high contrast of over 300:1 and multi-step structures. The errors are less than 1% for both root mean square error and contrast, and there is a remarkable improvement in the signal-to-noise ratio by over 50%. During the evaluation of experimental waveforms, the model can obtain different denoised waveforms with contrast greater than 200:1. The stability of the model is verified using temporal waveforms with identical pulse widths and contrast, ensuring that while achieving smooth temporal profiles, the intricate details of the signals are preserved. The results demonstrate that the denoising model, trained utilizing the simulation dataset, is capable of efficiently processing complex temporal waveforms in real-time for experiments and mitigating the influence of electronic noise and FM-to-AM on the time–power curve.

External seeded free-electron lasers (FELs) have exhibited substantial progress in diverse applications over the last decade. However, the frequency up-conversion efficiency in single-stage seeded FELs, particularly in high-gain harmonic generation (HGHG), remains constrained to a modest level. This limitation restricts its capability to conduct experiments within the ‘water window’. This paper presents a novel method for generating coherent X-ray FEL pulses in the water window region based on the HGHG scheme with multi-stage harmonic cascade. Without any additional modifications to the HGHG configuration, simulation results demonstrate the generation of intense 3 nm coherent FEL radiation using an external ultraviolet seed laser. This indicates an increase of the harmonic conversion number to approximately 90. A preliminary experiment is performed to evaluate the feasibility of this method. The proposed approach could potentially serve as an efficient method to broaden the wavelength coverage accessible to both existing and planned seeded X-ray FEL facilities.