The European Physical Journal D最新文献

In the present work, we studied electron-assisted molecular processes for plasma feed gases, TiCl_x and CF_x (x = 1 − 4). These radicals and their parent molecules are of great interest due to their importance for developing plasma reactors and other industrial applications. It is imminent to study charge transport for these molecules to model various phenomena involving ionization. We have calculated total ionization ((Q_{{{text{ion}}}})), elastic ((Q_{{{text{el}}}})), and total ((Q_{{{text{tot}}}})) cross sections using the quantum spherical complex optical potential (SCOP) formalism aided with the complex scattering potential–ionization contribution (CSP-ic) method. The present results are the first report for TiCl_x (x = 1 − 3) radicals in this work.

Graphical Abstract

Partial and total ionization

To understand ion transport properties, such as ion mobility, using the classical approach of diatomic ions in atomic gas at low temperatures, we employed two methods to calculate the mobility of ({text{CO}}^{+}) ions in helium gas. Both methods are performed using the ab initio potential energy surfaces provided by Gharibi et al. We used the modified version of Monchick–Mason approximation MMA2 to calculate the effective transport cross sections and effective potentials. The results obtained are compared with the available experimental data.

Graphical abstract

Comparison of effective cross-section MMA2Q and effective potential MMA2V non-zero-field mobilities K_0 of ({text{CO}}^{+}) ions in He gas with experimental data, at T=300 K as a function of E/N. The solid line is obtained from the effective cross-section MMA2Q, the dashed line is from the effective potential MMA2V, and the solide circle with error bars corresponds to experimental data. The horizontal line indicate the polarization limit (K_{(pol)}=16.35;{rm{cm}}^2 V^(-1) s^(-1).)

The integration of topological principles with rainbow trapping techniques presents a transformative approach in photonic device design, particularly in developing photonic topological rainbow based on quantum Hall effect. In this paper, we propose a quantum spin Hall photonic crystal with gradient radius of circles to achieve topological rainbow trapping, demonstrating trapping effect within topological edge states through fine-tuning. Theoretical and numerical analyses show that the topological rainbow is capable of capturing photonic states across a range of frequencies. Moreover, by modulating the group velocity of the edge states, we can effectively direct the path of light propagation, enabling selective light trapping within specific regions. The strategy outlined in this study offers a universal approach to topological rainbow trapping, which is anticipated to significantly advance the research and development in the domain of topological photonic devices.

Graphical abstract

The solutions to the classical problem of initial perturbation development (PIPD) for various types of flow instabilities (FI) in dissipative plasma are presented as well as the consequences. FI are due to the relative motion of plasma components (beam-plasma instabilities (BPI), the Buneman instability, etc.). The problem provides the most complete information on developing instabilities. The usual stumbling block in such type problems—the integral for the developing fields with the dispersion relation in the denominator of the integrand—for the first is overcome by direct integration. The holistic and versatile pictures of various FI spatiotemporal evolutions are presented. They show that with an increase in the level of dissipation any FI transforms into dissipative flow instability (DFI). Until recently, only one type of DFI in beam-plasma systems was known. Its maximal growth rate is (sim sqrt {n_{b} /nu }) ((n_{b}) is the beam density, (nu) is the plasma collision frequency). All BPI regardless on type (Cherenkov, cyclotron, etc.) transform into it. Two new, previously unknown types of DFI follow from PIPD solutions. The first one develops in systems where the e-beam and the plasma are spatially separated by a significant distance. Its growth rate is (sim sqrt {n_{b} } /nu). The second new DFI develops in a uniform cross-section magnetized plasma-filled waveguide with an over-limiting e-beam. Its maximal growth rate is (sim n_{b} /nu). Both new dissipative instabilities in beam-plasma systems (DIBPSs) develop in geometry similar to geometry of plasma microwave devices based on relativistic e-beams. The geometry is cylindrical waveguide with thin tubular plasma and thin tubular e-beam of grater radius. The study on these devices has two basic trends of development: increasing power and operating frequency. To increase the power it is necessary to increase beam current up to over-limiting values. Increasing frequency leads to decreasing of the skin-depth in the walls of resonators. Dissipation increases and the conditions for the new DIBPS development may be satisfied. This emphasizes importance of investigations on new DIBPS.

Graphical abstract

Multilayered spherical particles play a significant role in modern science and technology. Morphology-dependent resonances (MDRs) in these particles are critical due to their extensive applications across various fields. However, the complexity of MDRs in multilayered spherical particles surpasses that of homogeneous particles. As a result, existing models mainly focus on MDRs in homogeneous particles or MDRs at the outermost interior interface of coated or multilayered sphere particles. In this paper, MDRs in three-layered spherical particles are investigated by reformulating the internal scattering efficiency of each layer. This redefinition allows for an independent and straightforward analysis of resonances layer-by-layer, enabling researchers to examine the resonance characteristics of specific inner layers and accurately identify resonance locations. The study explores the relationships between MDRs in each layer, outermost scattering efficiency and partial wave to confirm the source of resonance. The findings of this study provide a theoretical foundation for studying MDRs of multilayered particles and their measurement.

Graphical abstract

The outermost scattering efficiency (k_{{{text{sca}}}}^{(4)}) curve exhibits resonant structures that correspond to the Morphology-dependent resonances (MDRs) in the inner layers, which can be effectively represented by the reformulated efficiencies k₁, k₂ and k₄. The MDRs in the lth layer are determined by the maxima of the Mie coefficients (left| {a_{n}^{(l + 1)} } right|)(or (left| {b_{n}^{(l + 1)} } right|)), leading to an enhancement of the electromagnetic fields in lth layers.