Excitation Of Modes Research Articles

A single dielectric nanoparticle for refractive index sensing

Abstract Refractive index sensing has great application potential in a wide range of chemical and biomedical fields, however, these sensors usually require large-area and fabrication-intense arrays of unit cells. Here, we propose an ultracompact sensor based on a single dielectric nanoparticle for refractive index sensing with a footprint smaller than 2 µm^2 and numerically investigate its sensing performance. A single-mode resonance rather than multimodes interaction is adopted for the spectroscopic feature of refractometric sensing. The elaborate resonator geometry facilitates the excitation of the gapped-vortex mode and enables the exposure of electric hotspots outside the dielectric. Such design enhances the coupling to the sensing medium, thus exhibiting high sensitivity at the level of 345 nm/RIU with a figure of merit of 12.78 per RIU. The single-particle nanostructure together with the single-mode resonance exhibits robust sensing performance to dimension deviations. Importantly, a thin annular beam is employed as the illumination to increase the excitation efficiency of the single-mode resonance, which significantly improves the modulation depth without relying on the near-field coupling of array nanostructures. This work provides a miniaturization platform for the dielectric sensors and other application fields based on enhanced light-matter interaction.

Simulation Research on the Dual-Electrode Current Excitation Method for Distance Measurements While Drilling

Based on a comprehensive analysis of the existing methods for measuring adjacent well distances, along with their advantages and disadvantages, this study employs theoretical analysis, simulation experiments, and other comprehensive research methods to investigate a distance measurement method based on current excitation. In response to the need for measuring and controlling the connection of relief wells, a method utilizing dual-electrode current excitation during drilling is proposed. This approach facilitates synchronous excitation measurements while drilling, significantly reducing both time and costs while ensuring safety and efficiency, making it particularly suitable for the connection operation of relief wells that involve safety risks. Firstly, this paper establishes a drilling with measurement model corresponding to the excitation mode, which derives the calculation formulas for the target casing current amplitude attenuation, as well as the induced magnetic field distribution within the formation. Additionally, it provides the calculation methods for determining the target well distance and azimuth direction. Lastly, the impact levels of various key factors are verified through numerical calculations and simulation analyses, which confirm the correctness and effectiveness of this distance measurement method. The findings from this research establish both a core theoretical foundation and a technological basis for the real-time measurement of adjacent well distances during relief well operations.

Advanced terahertz refractive index sensor in all-dielectric metasurface utilizing second order toroidal quasi-BIC modes for biochemical environments

We present a novel design for an all-dielectric metasurface ultra-sensitive refractive index (RI) sensor, characterized by a high-quality factor (Qf) and figure of merit (FOM). This design incorporates two high-order toroidal modes, including electric toroidal quadrupole (\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\:{Q}_{T}^{e}$$\\end{document}​) and magnetic toroidal quadrupole (\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\:{Q}_{T}^{m}$$\\end{document}​) based on quasi‑bound states in the continuum (q-BIC) resonances. Our findings demonstrate the feasibility of switching between \\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\:{Q}_{T}^{e}$$\\end{document} and \\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\:{Q}_{T}^{m}$$\\end{document}​ through various symmetry-breaking mechanisms. To excite these high-order toroidal modes, we explored several symmetry-breaking strategies, including complex structural designs, symmetry disruption, and variations in the incident wave angle. Symmetry breaking in the structure induces new modes in the transmission spectrum, which are highly advantageous for sensing applications due to the presence of dark modes. The designed metasurface exhibits the capability to sense a broad range of RI in diverse environments, particularly in biochemical fields. Sensitivity (S) is significantly enhanced by the excitation of new resonance modes and adjustments in the incidence angle, increasing from 217 GHz/RIU in a symmetrical structure to 512.3 GHz/RIU for \\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\:{Q}_{T}^{e}$$\\end{document}​. The FOM improves from 197 RIU 1 to 8538 RIU− 1 for \\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\:{Q}_{T}^{e}$$\\end{document}​ and 152,395 RIU− 1 for \\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\:{Q}_{T}^{m}$$\\end{document}​. Additionally, the Qf rises from 872 to 17,983 and 921,351 for \\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\:{Q}_{T}^{e}$$\\end{document}​ and \\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\:{Q}_{T}^{m}$$\\end{document}​, respectively.

Theoretical investigation of the excitation of leaky modes for multi-layered models

Summary The dispersion analysis with array-based methods enables us to detect and analyse the multi-mode dispersive waves with weak amplitudes. Over the past years, there has been widespread extraction of higher normal modes from earthquake records and ambient noise, which have been extensively employed in near-surface and crustal investigations. Notably, the frequent reporting of leaky modes in recent observations has gained significant attention. This is because leaky modes can provide more constraints on subsurface structures. Particularly, a subset of leaky modes is found to be sensitive to P-wave velocities, which has the potential to compensate for the limitations of traditional surface wave inversion. Nevertheless, due to the lack of knowledge of the excitation and practical application of leaky modes, it is urgent to have an effective guide in selecting certain leaky modes for practical inversion combined with other imaging methods. To this end, the theoretical investigation into the excitation of leaky modes for multi-layered models is undertaken. By computing theoretical seismograms for various source mechanisms and source depths with the discrete wavenumber method and the normal-mode summation method respectively, the qualitative evaluation of the leaky-mode contributions to the synthesized seismograms is conducted. Additionally, the impact of the source depth for the same source mechanism is meticulously examined by the dispersion spectra. Furthermore, with the accurate computation of leaky modes, we categorize the leaky modes into PL and OP (organ-pipe) modes according to their distinctive properties, i.e., their attenuation and eigen-displacements, which may be used to explain very well the occurrence of certain leaky modes on the dispersion spectrum and be indicative of the reasonable choice of PL modes to put them into practical inversion for P-velocity structures.

Measurement of temporal evolution of antiferromagnetic domain change in nickel oxide driven by 2TO phonon mode excitation via pump-probe experiment

Abstract The temporal evolution of antiferromagnetic domain pattern changes under resonant excitation of the second-order transverse optical (2TO) phonon mode in nickel oxide was investigated using mid-infrared free electron laser (MIR-FEL) pulses and visible nanosecond probe laser pulses at room temperature. We visualized the domain patterns through magneto-optical polarized microscopy in transmission and observed their temporal variation after the phonon excitation via MIR-FEL. We evaluated the differences throughout the timeline using the structural similarity index measure (SSIM) technique from domain images with and without MIR-FEL irradiation. We found that the MIR-FEL irradiation induces significant structural changes in the domain patterns. The maximum difference was observed at the timing of the MIR-FEL irradiation and exponentially recovered with the time constant of 1.4 ± 0.2 ms. This rather long-time constant could be owing to the spin relaxation, whilst further investigation is needed to confirm the underlying mechanism.

Electromagnetic fields transformation in UWB infinite antenna arrays in the cluster excitation mode

Infinite ultra-wideband (UWB) arrays of TEM horns and Vivaldi antennas were considered. At the first stage we used an array model in the quasi-periodic excitation mode in the form of a Floquet channel. It was implemented in the HFSS electromagnetic modeling system. At the second stage the array parameters in the cluster excitation mode were determined using the calculated scattering matrix of the Floquet channel. Two clusters of TEM horns and Vivaldi antennas were analyzed. They were finite along one coordinate and infinite along the other. It was investigated how the cluster size, frequency, amplitude distribution of exciting waves, scanning in the sector of angles affect the shape of the amplitude-phase distribution of the field in the array aperture. It was shown that the field distribution in the emitting aperture may differ significantly from the distribution of exciting waves at the inputs of the array elements. An explanation of this effect based on the representation of the field in the array in the form of a superposition of its eigen waves was proposed.

Role of nonthermal solar wind protons in the excitation of electromagnetic proton-cyclotron instability: a kinetic theory based exact numerical investigation

Free transverse kinetic energy i.e. perpendicular temperature anisotropy of protons excite the electromagnetic ion/proton cyclotron instability which is pertained to waves associated with prevalent electromagnetic ion/proton cyclotron emissions in various natural regions of plasmas. The transverse dielectric response function of left hand circularly polarized electromagnetic proton cyclotron (EPC) instability is calculated for two models of nonthermal Cairns distributed plasmas. These models are distinguished according to the effective thermal velocities of protons. For the energetic nonthermal protons populations, nonthermality dependent effective temperature model is proposed which significantly contributes in the excitation of aforementioned plasma mode and cause an appreciable enhancement in the instability growth rate. Exact numerical solution of dispersion relation yields oscillatory real frequency and growth rate of instability. A comparative analysis is also carried out to examine the instability behavior in distinct nonthermal and thermal plasma models. Contemporary numerical investigations are highly beneficial to understand the intricate dynamics of space plasmas.

Characterizing temporal stability of supercontinuum generation in higher-order modes supported by liquid-core fibers

The generation of tailored supercontinua is essential for studying ultrafast light-matter interactions and for a variety of practical applications requiring broadband light. Liquid-core fibers (LCFs) have emerged as an innovative nonlinear photonic platform, demonstrating high efficiency in nonlinear frequency conversion. In this study, we showcase that LCFs provide a stable platform for ultrafast supercontinuum generation in a selected higher-order vector mode at 1.55μm\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$1.55\\;\\upmu \\hbox {m}$$\\end{document}. Specifically, we demonstrate soliton fission and double-dispersive wave generation using a radially polarized mode in a CS2\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\hbox {CS}_{2}$$\\end{document}-silica liquid-core fiber. The experiments were performed in a temperature-controlled laboratory, showing excellent stability with no evidence of fiber degradation, material degradation, or drift-induced changes in mode excitation over extended periods under standard environmental conditions. Our results confirm that liquid-core fibers are a reliable platform for nonlinear photonics, suitable for applications such as computationally tailored supercontinuum generation, single pulse spxectroscopy, and tailored light sources, all of which rely on consistent and stable nonlinear frequency conversion.

Transverse magnetic supermodes in plasmonic optical fibers excited by radially polarized light

The overlap integrals method, with a fully vectorial formulation, is used to model the selective excitation of the TM01 mode in a few-mode optical fiber with a radially polarized donut beam, and its coupling to guided modes having a plasmonic character (supermodes). The analyses were performed on a waveguide formed as a step-index few-mode optical fiber coated with a thin gold film, at an operating wavelength of 1310 nm. The waveguide was found to support modes having optical fiber, circular metallic waveguide, and surface plasmon characteristics, depending on geometrical and material parameters. Three purely bound transverse magnetic (radially polarized) supermodes were identified: Two symmetric, labeled sTM01 and sTM02 modes, and one asymmetric, labeled ab mode, where symmetry pertains to the transverse electric field distribution over the gold film. The effective mode indices of the supermodes were studied as a function of the thickness of the gold film and its proximity to the fiber core. Considerations for the selective excitation of the sTM01 mode are discussed along with its possible applications. The transmittance of the supermodes is found to be robust even at sharp waveguide transitions. The results predict that effective excitation of TM supermodes with strong plasmonic character, without significant coupling losses, can be achieved by exciting the fiber with a radially polarized donut beam.

Plasma-based base flow modification on swept-wing boundary layers: dependence on flow parameters

This work examines the control of cross-flow instabilities (CFIs) and laminar–turbulent transition on a swept wing, through the plasma-based base flow modification (BFM) technique. The effect of experimentally derived plasma body forces on the steady boundary layer base flow is explored through numerical simulations. Linear stability theory is subsequently used to predict the net BFM effect on CFIs. Based on these preliminary predictions, experiments are conducted in a low-turbulence wind tunnel where a spanwise-invariant plasma actuator is installed near the wing leading edge and operated at constant input voltage and frequency. Various flow parameters governing the plasma-based BFM technique are investigated, namely the Reynolds number, angle of attack and wavelength of excited stationary CFI modes. Stationary and travelling CFIs are quantified by planar particle image velocimetry while the transition topology and location are recorded by infrared thermography. The results confirm the stabilising effect of BFM on the swept-wing boundary layer. However, the plasma-based BFM is found to render the boundary layer more susceptible to travelling CFIs. In the presence of both net BFM effect and intrinsic plasma unsteady perturbations, the plasma-based BFM technique achieves transition delay with specific combinations of Reynolds number, angle of attack and wavelength of excited stationary CFI modes. The present findings provide insights into the fundamental principles of operating plasma actuators within the context of BFM control.

Measurement of Oscillatory and Dissipative Resonator Characteristics of Solid-State Wave Gyroscopes: Algorithms for Operational Correction of Systematic Signal Drift

The article discusses the possibilities of increasing the output signal accuracy of integrating solid-state wave gyroscopes manufactured with a reduction in the requirements for the residual characteristics of the multi-frequency and multi-factor ratios of their resonators, as well as for the centering of the control ring electrode. These capabilities involve the use of a more complex output function that includes an additional part due to the effect of these errors on the systematic drift function. However, its formation requires introduction of an interval shutdown of the parametric excitation system so as to increase the purity of identification of the listed factors. To reveal this topic, the following is sequentially described: mathematical formulation of the problem; general analysis of the systematic drift of the integrating gyroscope signal caused by mechanical errors in the design of its resonator; autonomous algorithmic reduction of the influence of the dominant residual differentials in the mode of interval disconnection of excitation; autonomous algorithmic reduction of the influence of the dominant residual frequency difference in the mode of interval disconnection of excitation; simultaneous algorithmic compensation of the influence of residual Q and Frequency in the interval disconnection mode of excitation; estimation of the signal drift component of the integrating gyroscope, due to errors in the control loops, as well as the possibility of its reduction. The analysis of these problems is carried out on the basis of a model of wave processes in the gyroscope resonator, obtained only on the basis of the laws of classical mechanics. There were no additional errors due to the imperfection of the electrical circuits for processing measurement and control signals. Various computational schemes discussed in the article can also be useful for performing operational adjustments of the gyroscope measurement system, which may be required as a result of the design aging factor, as well as after its intensive use in a wide range of external disturbances.

Reply to the Comment on “A New Boson Expansion Theory Utilizing a Norm Operator”

Abstract The comment is based on misunderstandings and, as a result, does not evaluate the norm operator method. We refute the comment. The structure of the norm operator composed of all the excitation modes determines whether the form of a practical boson expansion is a small parameter expansion. KT-3 is chimerical. It should be taken seriously that the small parameter expansions do not hold with truncating the contributions of all phonon excitation modes that are not adopted as boson excitations. The formulation using the boson expansion of the projection operator on to the boson vacuum does not allow the limitation of the phonon excitation number beforehand.

Theoretical Study on Transverse Mode Instability in Raman Fiber Amplifiers Considering Mode Excitation.

Raman fiber lasers (RFLs), which are based on the stimulated Raman scattering effect, generate laser beams and offer distinct advantages such as flexibility in wavelength, low quantum defects, and absence from photo-darkening. However, as the power of the RFLs increases, heat generation emerges as a critical constraint on further power scaling. This escalating thermal load might result in transverse mode instability (TMI), thereby posing a significant challenge to the development of RFLs. In this work, a static model of the TMI effect in a high-power Raman fiber amplifier based on stimulated thermal Rayleigh scattering is established considering higher-order mode excitation. The variations of TMI threshold power with different seed power levels, fundamental mode purities, higher-order mode losses, and fiber lengths are investigated, while a TMI threshold formula with fundamental mode pumping is derived. This work will enrich the theoretical model of TMI and extend its application scope in TMI mitigation strategies, providing guidance for understanding and suppressing TMI in the RFLs.

All-dielectric ellipsoidal tetramer metasurface sensor with multi-resonances from the bound states in the continuum.

We demonstrate an all-dielectric tetramer metasurface that achieves high-precision refractive index sensing through the excitation of toroidal dipole, magnetic dipole, and electric quadrupole modes, driven by bound states in the continuum (BIC). The metasurface exhibits exceptional performance, with a quality factor of 4.65 × 104, a sensitivity parameter of 649 nm/RIU, and a figure of merit of 1.51 × 104 RIU-1, achieved by optimizing symmetry and lattice perturbations in periodic silicon tetramer ellipsoidal nanodisks on a SiO2 substrate. Additionally, the sensor effectively distinguishes analytes with extinction coefficient differences as small as 0.01 through enhanced broadband absorption. This innovation demonstrates substantial potential for label-free sensing applications in microfluidic chip integration.

The influence of the tyre air cavity on the rolling noise

Road traffic is the main source of environmental noise. While combustion noise has been reduced over the years, it appears to be difficult to reduce rolling noise. Even for electrical vehicles at moderate speeds rolling noise is a main contributor to the exterior noise. The main cause of rolling noise is the excitation of vibrations on the tyre structure by contact forces due to varying road roughness and/or tyre profile. However, we know that when rolling over obstacles like rails or bridge joints, the cavity noise due to the excitation of tyre cavity modes is clearly audible. Therefore, one can assume that cavity modes also contribute to tyre/road noise on rough roads. This paper makes the attempt to demonstrate the contribution of cavity noise as function of road roughness and tyre profile. The Chalmers tyre/road interaction model is used for the simulations. A modified radiation model allows for calculating the contribution of each individual tyre mode to the radiated sound. In this way the contribution of the cavity modes can be determined. Results indicate that at least for rough road surfaces the contribution of the cavity modes is of importance for the exterior sound.

Compact Substrate Integrated Waveguide Cubical Dielectric Resonator Antenna for fifth-generation applications

A comprehensive analysis of a wideband Cubical Dielectric Resonator Antenna is presented, specifically designed for 5G-NR wireless communication applications, focusing on the N257, and N258 frequency bands. This antenna exhibits symmetrical radiation patterns, a wider bandwidth, improved efficiency, and substantial gain characteristics. The design employs a low-loss substrate-integrated waveguide structure to enhance gain while reducing cross-polarization effects. This is accomplished through an innovative approach of establishing boundary conditions using copper wire stitching for vias, superseding the conventional soldering iron method, which guarantees minimal radiation leakage, compact dimensions, and reduced losses. The perforated dielectric resonator antenna possesses higher mode excitations, and implementing metallic strips on two resonator surfaces facilitates the simultaneous excitation of fundamental and higher-order modes, thereby yielding a broadband response. The overall dimensions of the antenna are 15.29 × 8.42 × 3.8 mm3(1.3×0.7×0.3)λ03, which facilitates a measured impedance bandwidth of 8.2 GHz, spanning from 24.4 to 32.6 GHz (28.7%), accompanied by a high gain of 8.1 dBi and efficiency levels reaching up to 94%. The prototype is constructed utilizing the standard printed circuit board technique, and simulation outcomes are derived using the High-Frequency Structure Simulator (HFSS).

Spatiotemporal chiroptical behavior of dielectric and plasmonic nanoparticles.

We theoretically examine the spatiotemporal evolution of near-field optical chirality (OC) in both plasmonic and dielectric nanospheres when excited by ultrashort optical pulses. We demonstrate distinct spatiotemporal variations in the near-field OC arising from the differing natures of plasmonic and dielectric resonators. The electric dipole resonant plasmonic nanosphere generates an instantaneous near-field OC that relies on the interference between incident and scattered (induced) fields. Conversely, a resonant dielectric nanosphere sustains a long-lasting OC even after the incident field vanishes, due to the scattered field from resonant electric and magnetic dipoles. We further demonstrate the control over the near-field OC using vector beams to tune electric and magnetic mode excitations. Our work opens up opportunities for spatiotemporal control of nanostructure-enhanced chiral light-matter interactions.

Excitation of the Gyrotropic Mode in a Magnetic Vortex by Time-Varying Strain.

We demonstrate the excitation of the gyrotropic mode in a magnetostrictive vortex by time-varying strain. The vortex dynamics is driven by a time-varying voltage applied to the piezoelectric substrate and detected electrically by spin rectification at subthreshold values of rf current. When the frequency of the time-varying strain matches the gyrotropic frequency at a given in-plane magnetic field, the strain-induced in-plane magnetic anisotropy leads to a resonant excitation of the gyration dynamics in the magnetic vortex. We show that nonlinear gyrotropic dynamics can be excited already for moderate amplitudes of the time-varying strain.

Spiking activities in small neural networks induced by external forcing.

Neurons in an excitable mode do not show spiking activity and, therefore, do not contribute to information transfer transmission and its processing. However, some external influences, coupling, or time delay can lead to the appearance of oscillations in individual systems or networks. The main goal of this paper is to uncover the connection parameters and parameters of external influences that lead to the arising of spiking behavior in a small network of locally coupled FitzHugh-Nagumo oscillators. In this study, we analyze the dynamics of a small network in the absence and presence of several types of external influences. First, we consider the impact of periodic-pulse exposure generated as a periodic sequence of Gaussian pulses. Second, we show what behavior can be induced by far less regular pulsed influence (Lévy noise) and its special case called white Gaussian noise. For all types of influences, we have identified the appropriate parameters (local coupling strength, intensity, and frequency) that induce spiking activity in the small network.

Full-wave simulations on helicon and parasitic excitation of slow waves near the edge plasma

Helicon waves are thought to be promising in various tokamaks, such as DIII-D, because they can penetrate reactor-grade high-density cores and drive the off-axis current with higher efficiency. In the frequency regime ∼ 476 MHz, both slow electrostatic and fast electromagnetic helicon waves can coexist in DIII-D. If the antenna parasitically excites the slow mode, these waves can propagate along the magnetic field line into the scrape-off layer (SOL). Although the importance of the misalignment of the Faraday screen and the electron density in the SOL on the excitation and propagation of slow modes is well known, the conditions for minimizing slow mode excitation have yet to be optimized. Using the Petra-M simulation code in the 2D domain, we analyze the effects of the misalignment of the antenna in the poloidal direction, the misalignment of the Faraday screen in the toroidal direction, and the density in front of the antenna on slow mode generation. Our results suggest that the misalignment of the Faraday screen is a critical factor in reducing the slow mode and that the misalignment angle should be below ∼ 5° to minimize the slow wave excitation. When the electron density is higher than 3.5×1018 m−3 in the SOL, the generation of the slow mode from the antenna is minimized and unaffected by the misalignment of the Faraday screen.