Electron Bernstein wave aided heating of collisional nanocluster plasma by nonlinear interactions of two super-Gaussian laser beams

In this present theoretical study, we investigate electron Bernstein wave (EBW) aided collisional nanocluster plasma heating by nonlinear interaction of two super-Gaussian laser beams. The interactions of laser beams electric field profiles with electronic clouds of nanoclusters cause the beat wave. The nonlinear ponderomotive force is generated through the beat wave. There may be good potential to excite the EBW aiding cluster plasma to lead electron heating via cyclotron damping of the Bernstein wave. An analytical scheme is proposed for the anomalous heating and evolution of electron temperature by using this mechanism. Graphical discussions were promised to achieve extreme heating rate via the spatial shape of super-Gaussian laser beams and the resonance condition of beat wave to surface plasmon frequency. The heating is controlled by tuning the laser beam width, mode index, collisional frequency, clustered radius, and density.

Interaction between energetic-ions and internal kink modes in a weak shear tokamak plasma

Based on the conventional tokamak HL-2A-like parameters and profiles, the linear properties and the nonlinear dynamics of non-resonant kink mode (NRK) and non-resonant fishbone instability (NRFB) in reversed shear tokamak plasmas are investigated by using the global hybrid kinetic-magnetohydrodynamic (MHD) nonlinear code M3D-K. This work mainly focuses on the effect of passing energetic-ions on the NRK and NRFB instabilities, which is different from the previous works. It is demonstrated that the NRFB can be destabilized by the passing energetic-ions when the energetic-ion beta $\beta_h$ exceeds a critical value. The transition from NRK to NRFB occurs when the energetic-ion beta $\beta_h$ increases to above a critical value. The resonance condition responsible for the excitation of NRFB is interestingly found to be satisfied at $\omega_t+\omega_p\approx\omega$, where $\omega_t$ is the toroidal motion frequency, $\omega_p$ is the poloidal motion frequency and $\omega$ is the mode frequency. The nonlinear evolutions of NRFB's mode structures and Poincar\'{e} plots are also analyzed in this work and it is found that the NRFB can induce evident energetic-ion loss/redistribution, which can degrade the performance of the plasmas. These findings are conducive to understanding the mechanisms of NRFB-induced energetic-ion loss/redistribution through nonlinear wave-particle interaction.

Novel Beam Scan Method of Fabry–Perot Cavity (FPC) Antennas

A new beam scanning method of a Fabry–Perot cavity (FPC) antenna is proposed. To obtain high gain in a target direction with a reduced sidelobe level (SLL), we devised a tapered partially reflective surface (PRS) as a superstrate. Moreover, to attain various beam scanning directions, a phase-controllable artificial magnetic conductor (AMC) ground plane with a broad reflection phase range and high reflection magnitudes was introduced. In the proposed method, a new formula to satisfy an FP resonance condition in a cavity for a scanned beam is also suggested. According to the formula, the FPC antenna can precisely scan the main beam in designed target directions with well-maintained high gain, which has been hardly achievable. In addition, our method demonstrates the potential of electrical beam-scanning antennas by employing active RF chips on the AMC cells. To validate the method, we fabricated a prototype FPC antenna for a scanned beam at θ = 30°. Furthermore, we conducted an additional simulation for a different beam scanning angle as well. Good agreement between the expected and experimental results verifies our design approach.

Nurturing Plasmonic Properties of Nanocomposite Thin Films: The Importance of Optimum Oblate Shape

Metal nanoparticles (MNPs) embedded dielectric thin films are very crucial for many optoelectronic applications. This report investigates various ways of tuning the plasmonic properties of such nanocomposite thin films. For this, the well-known plasmon resonance condition was first generalized to include the shape and volume fraction of MNPs. This was followed by deriving an empirical formula for the resonance position (λR) which was worked out to be the positive root of a quadratic equation. The coefficients of the deduced quadratic relation involve the parameters obtained from the empirical fit to some of the experimental dielectric functions of MNPs available in literature. The derived working formula enables research community to tune the LSPR of nanocomposites in the whole range of visible wavelengths. The derived formula also concluded that with known lower volume fractions, shape of MNPs affects λR the most, compared to the other parameters. The derived formula was validated by calculating the full extinction spectra. It was shown for the first time that there exists an optimum value of oblate shape to give maximum resonance for a given nanocomposite.

The Numerical Analysis for Parametric Resonance of Multicable System considering Interaction between Adjacent Beam Portions

The investigation aims to propose a refined model to analyze the parametric resonance under multicable systems such as cable-stayed bridges. Considering the interaction between the adjacent beam portions, the shear difference is applied to modify the vibration equations derived from the multi-degree-of-freedom stiffness method. Furthermore, the difference method is adopted to make the equations more accessible for numerical analysis. The comparison results indicate that the refined model exhibits the key character of parametric resonance and also further verified the simulation methods. The consequences show that the cable will resonate at the fundamental frequency under the support excitation. In particular, when resonance occurs, most of the energy in the subsystem is transferred to the cable, resulting in the resonance amplitude of the beam portion being weakened to some certain extent. Moreover, the global resonance will have a sufficient excitation on the local resonance only when the resonance condition is satisfied.

Efficient Optical Sensing Based on Phase Shift of Waves Supported by a One-Dimensional Photonic Crystal

Interferometric methods of optical sensing based on the phase shift of the Bloch surface waves (BSWs) and guided waves (GWs) supported by a one-dimensional photonic crystal are presented. The photonic crystal, composed of six SiO2/TiO2 bilayers with a termination layer of TiO2, is employed in the Kretschmann configuration. Under resonance condition, an abrupt phase change is revealed, and the corresponding phase shift is measured by interferometric techniques applied in both the spectral and spatial domains. The spectral interferometric technique employing a birefringent quartz crystal is used to obtain interference of projections of p- and s-polarized light waves reflected from the photonic crystal. The phase shifts are retrieved by processing the spectral interferograms recorded for various values of relative humidity (RH) of air, giving the sensitivity to the RH as high as 0.029 rad/%RH and 0.012 rad/%RH for the BSW and GW, respectively. The spatial interferometric technique employs a Wollaston prism and an analyzer to generate an interference pattern, which is processed to retrieve the phase difference, and results are in good agreement with those obtained by sensing the phase shift in the spectral domain. In addition, from the derivative of the spectral phase shifts, the peak positions are obtained, and their changes with the RH give the sensitivities of 0.094 nm/%RH and 0.061 nm/%RH for the BSW and GW, respectively. These experimental results demonstrate an efficient optical sensing with a lot of applications in various research areas.

Inflation based on a classically scale invariant extended standard model

We extend a classically scale invariant model where the electroweak symmetry breaking is triggered by the dynamical chiral symmetry breaking in a hidden QCD sector, and a real singlet scalar [Formula: see text] mediates these two sectors. Our model can explain cosmic inflation without unitarity violation in addition. Slow-roll inflation occurs along a valley in scalar potential. In the original model, the coupling [Formula: see text] between the Higgs field [Formula: see text] and [Formula: see text] is always negative and therefore, the potential has its valleys in [Formula: see text]-[Formula: see text] mixed directions. For large value of the top Yukawa coupling [Formula: see text], the potential along the valley becomes negative since the Higgs quartic coupling [Formula: see text] becomes negative at inflationary scale. Then slow-roll inflation cannot occur. For inflation to definitely occur, we render the coupling [Formula: see text] positive at inflationary scale and consider the [Formula: see text]-inflation case. This is achieved by introducing a new singlet scalar [Formula: see text] with the large coupling [Formula: see text] to [Formula: see text]. By this extension, [Formula: see text] can also always be positive, and we consider this case as the simplest case. We consider inflation with the nonminimal coupling [Formula: see text] between [Formula: see text] and gravity. Although [Formula: see text] is large such as [Formula: see text], unitarity is not violated since couplings between [Formula: see text] and other fields are sufficiently small. [Formula: see text] is odd under a new symmetry [Formula: see text] not to mix with [Formula: see text] regardless of largeness of [Formula: see text]. Because of this symmetry, [Formula: see text] may have its relic abundance [Formula: see text] comparable with the observational value [Formula: see text] of the dark matter relic abundance. However, the spin-independent elastic cross-section [Formula: see text] of [Formula: see text] exceeds the observational bound [Formula: see text] cm2. Hence, we impose the resonance condition [Formula: see text] and reduce [Formula: see text] to much smaller than [Formula: see text]. Constraints from the electroweak scale physics and inflationary scale physics are much strong, and the allowed parameter space is very narrow.

The Helical Resonator: A Scheme for Radio Frequency Plasma Generation

The helical resonator is a scheme for the production of high voltage at radio frequency, useful for gas breakdown and plasma sustainment, which, through a proper design, enables avoiding the use of a matching network. In this work, we consider the treatment of the helical resonator, including a grounded shield, as a transmission line with a shorted end and an open one, the latter possibly connected to a capacitive load. The input voltage is applied to a tap point located near the shorted end. After deriving an expression for the velocity factor of the perturbations propagating along the line, and in the special case of the shield at infinity also of the characteristic impedance, we calculate the input impedance and the voltage amplification factor of the resonator as a function of the wave number. Focusing on the resonance condition, which maximizes the voltage amplification, we then discuss the effect of the tap point position, dissipation and the optional capacitive load, in terms of resonator performance and matching to the power supply.