Ordinary Mode Research Articles

Characteristics of ordinary mode in fully relativistic electron plasma

Propagation characteristics (resonances, propagation regions, and cutoffs) of ordinary waves (perpendicularly propagating electromagnetic waves) are studied in a relativistic electron plasma by using the kinetic model. The dispersion relation for the ordinary mode (O-mode) in a relativistic electron plasma is investigated by employing the Maxwell-Boltzmann-Jüttner distribution function. As the integration in the relativistic dispersion relation cannot be done analytically so an approximated value is obtained using the trapezoidal rule. Various modes of propagation for the ordinary waves are observed for each harmonic number n due to the relativistic effects defined by the value . We also observe that the high-temperature relativistic plasma environment is more transparent for the O-mode as compared to weakly relativistic and non-relativistic plasma environments. Moreover, the cutoff points are shifted to lower values in the relativistic limit.

Intensification of microwave radiation by hybridized plasmon effect

In recent years, an innovative technology based on modulation and enhancement effects of subwavelength plasma on RF electromagnetic radiation has been proposed, in which the microwave radiation from an electrically small antenna can be significantly enhanced when the antenna is tightly enclosed by a subwavelength overdense plasma shell. But the exact mechanism is still not entirely clear. In this paper, we first use the theory of hybridized Local Surface Plasmon Resonance (LSPR) for visible light in nanometal to explain this cross-domain work of microwave radiation enhancement modulated by a subwavelength overdense plasma layer, and the results show that the LSPR frequency is in good accordance with the frequency of enhanced radiation signals. Furthermore, the relationship between LSPR and antenna impedance as well as their effects on the impedance matching condition between antenna and power supply are investigated. It is indicated that LSPR on the plasma layer changes the impedance of the antenna, which produces circuit resonance (differing from plasmon resonance) between the antenna and power supply, and thus more power is radiated from the power supply to free space.

Annulment of the decision by the Warsaw’s Real Estate Reprivatisation Commission

In the scope of verification of administrative decisions relating to the implementation of the effect of the nationalization of Warsaw real estate after World War II, Polish legislative introduced a number of instruments of a procedural inscribing into the traditional catalogue of extraordinary modes of verification of administrative decisions. One of such instruments was the annulment of the administrative decision introduced into a specific arsenal of legal means available to the Warsaw’s Real Estate Commission. Annulment of the decision by the Warsaw’s Real Estate Reprivatisation Commission is the extraordinary verification issue like special administrative decision described in art. 156 of the Code of Administrative Procedure.

Thermally induced generation and annihilation of magnetic chiral skyrmion bubbles and achiral bubbles in Mn–Ni–Ga magnets

Magnetic chiral skyrmion bubbles and achiral bubbles are two independent magnetic domain structures, in which the former with an equivalent winding number to skyrmions offer great promise as information carriers for further spintronic devices. Here, in this work, we experimentally investigate the generation and annihilation of magnetic chiral skyrmion bubbles and achiral bubbles in the Mn–Ni–Ga thin plate by using Lorentz transmission electron microscopy (L-TEM). The two independent magnetic domain structures can be directly controlled after field cooling manipulation by varying the titled angles of external magnetic fields. By imaging the magnetization reversal with increasing temperature, we found an extraordinary annihilation mode of magnetic chiral skyrmion bubbles and a non-linear frequency for the winding number reversal. The quantitative analysis of such dynamics was performed by using L-TEM to directly determine the barrier energy for the magnetization reversal of magnetic chiral skyrmion bubbles.

Status and Plans for the DIII-D ECH/ECCD System

The DIII-D electron cyclotron heating and current drive (ECH/ECCD) system has been operating with an annual average of 4268 individual gyrotron pulses into the plasma in the last four years and 3-3.6 MW average yearly power availability in the last ten years. This allowed an increase in the number and the range of experiments involving injection of 110 and 117.5 GHz EC power into the DIII-D tokamak plasma. Some of the operational limitations encountered for the 110 GHz X-mode second harmonic resonance scenario launched in overdense plasmas were bypassed with the alternative use of O-mode second harmonic launch and the addition of a new higher frequency gyrotron at 117.5 GHz. A new launcher that will inject the EC waves downward nearly parallel to the resonance layer with higher current drive efficiency and a long absorption path was built and is now installed. Some of the remaining gyrotrons have been successfully in service as long as 14 years and need to be replaced; major plans for commissioning and purchasing a new series of gyrotrons in addition to the repair and refurbishment of the older ones are under way. The number of gyrotrons will increase bringing the generated power up to 10 MW in the next few years.

The beam pulse amplifier in space and laboratory plasmas

We discuss the physical background of the a new mechanism in which short electromagnetic pulses can be strongly amplified by interaction with suprathermal electrons in a near-equilibrium near-uniform magnetised plasma layer. This occurs under the special condition that the wave phase and group speeds along the field lines are equal, a condition met by extraordinary mode electromagnetic waves propagating in the medium. In this case the pulse interacts strongly via the Čerenkov resonance with suprathermal electrons moving along the field lines at the same speed as the pulse, leading to rapid wave growth, the instability within the pulse being shown to be equivalent to that of a monoenergetic electron beam moving along the field lines in an infinite uniform plasma. This effect accounts for basic features of powerful pulsed electromagnetic emissions in planetary magnetospheres, specifically whistler-mode chorus emissions in space plasmas, the remarkable radio emissions observed from brown dwarf objects, as well as in laboratory plasma.

Thermonuclear fusion triggered by collapsing standing whistler waves in magnetized overdense plasmas

Thermal fusion plasmas initiated by standing whistler waves are investigated numerically by two- and one-dimensional particle-in-cell simulations. When a standing whistler wave collapses due to the wave breaking of ion plasma waves, the energy of the electromagnetic waves transfers directly to the ion kinetic energy. Here we find that ion heating by use of standing whistler waves is operational even in multidimensional simulations of multi-ion species targets, such as deuterium-tritium (DT) ices and solid ammonia borane (H_{6}BN). The energy conversion efficiency to ions becomes as high as 15% of the injected laser energy, which depends significantly on the target thickness and laser pulse duration. The ion temperature could reach a few tens of keV or much higher if appropriate laser-plasma conditions are selected. DT fusion plasmas generated by this method must be useful as efficient neutron sources. Our numerical simulations suggest that the neutron generation efficiency exceeds 10^{9} n/J per steradian, which is beyond the current achievements of the state-of-the-art laser experiments. Standing whistler-wave heating would expand the experimental possibility for an alternative ignition design of magnetically confined laser fusion and also for more difficult fusion reactions, including the aneutronic proton-boron reaction.

Effective Gyroresonance Layers in the Transition Region of the Active Region of the Solar Atmosphere. Magnetic Fields and Heights

Abstract—We present a method of determination of numbers of gyroresonance layers most effectively radiating in the transition region of the active solar atmosphere. It is based on determination of frequency in the spectrum of an extraordinary wave of an active region, at which the gradient of this spectrum abruptly rises. Observations of 29 active regions carried out at the RATAN-600 radio telescope have been analyzed. The magnetic field in the transition region was determined from the frequency of bending point in the spectrum of antenna temperatures in an extraordinary mode under condition of emission in the third harmonic of the gyrofrequency. The relation between the photospheric magnetic field strength and the magnetic field strength in the transition region (1.52–2.28) is substantially greater than previously obtained, namely, the field isdecreasedonlyby10–20% in the transition region. The heights in the transition region were determined from the reconstructed magnetic field in the nonlinear force-free approximation, and are in the range of 1.00–3.57 Mm.

420 Vortex formation in the pre-ejection phase in the left ventricle

Abstract Funding Acknowledgements Central Norway Regional Health Authority Background/Introduction: Vortex formation during left ventricular filling have been described since the 1980’s. We have investigated vortices in the left ventricle (LV) in healthy adults with a new technology based on high frame rate vector flow imaging (VFI) using blood speckle tracking. Purpose In this study we investigated the intraventricular flow pattern during the pre-ejection period. Material and methods We examined 21 healthy volunteers with a GE E95 ultrasound scanner, both in ordinary clinical mode and with an experimental setup. The latter was developed to achieve high frame rates by utilizing plane waves in combination with ECG-gating over multiple (5-6) heart cycles, allowing continuous acquisition of > 3500 FPS. Blood speckle tracking followed by model based regularization was used to obtain vector flow velocity measurements. Results During the pre-ejection phase we observed blood flow from the apex to the basis of the LV along the septum. At the base, the flow is deflected. A basal vortex is then created just above the mitral valve, which persists into the isovolumetric contraction (IVC). The lateral part of the vortex is then seen as an apically directed flow during IVC, as shown in the illustration. The vortex is also visible in the first phase of the ejection; the part of the blood in the LV not passing through the aortic valve is deflected and continues to conserve this vortex. These findings correspond to patterns found in colour M-Mode (CMM), showing a column of blood toward the apex in the IVC/early ejection phase. Time from peak R to the first sighting of this IVC vortex, and to the pre-ejection spike in tissue Doppler imaging (TDI), are similar, as reported in table 1. Conclusion(s): Our imaging setup allows for a very high temporal resolution (>3500 FPS), and enables VFI using blood speckle tracking, without using a contrast agent. We observed an intraventricular vortex during pre-ejection and into early ejection, with the same direction as the later vortices seen in filling. Initiation of this vortex may be conserved energy from late filling. This vortex is simultaneous with the pre-ejection spike in TDI. We postulate that this IVC vortex contributes to the closing of the anterior mitral leaflet in the IVC. As we also observe this vortex during the early ejection phase, we believe it may conserve rotational energy into early filling. Table 1 Timing of the IVC vortex and the pre-ejection spike in TDI Mean Median SD Min Max Time between R and the basal vortex during IVS (ms) 16,7 16 15,1 -13 47 Time between R and the pre-ejection spike TDI (ms) 16,3 21 14,4 -10 36 Abstract 420 Figure.

Performance Evaluation of NOMA for Sidelink Cellular-V2X Mode 4 in Driver Assistance System With Crash Warning

This article presents the performance characteristics of a potential extension of sidelink cellular-vehicle-to-everything mode 4 (simply called mode 4) with uplink non-orthogonal multiple access (UL-NOMA), named SPS-NOMA, in driver assistance systems with a crash warning. In SPS-NOMA, multiple nodes (e.g., cars or pedestrians with communication equipment) simultaneously broadcast their data frames at a time-frequency resource selected by sensing-based semi-persistent scheduling (sensing-based SPS), the distributed random access protocol of mode 4. The transmitted signals are superposed at the receiver sides, and successive interference canceller (SIC) supports decoding the superposed signal. In SPS-NOMA, sensing-based SPS is expected to enhance the signal-to-interference-plus-noise ratio at each SIC iteration. The effect boosts the performance gains of the SIC in broadcast cases and mitigates the channel congestion. Our computer simulations highlighted that SPS-NOMA improved the performance of the ordinary mode 4 by 38% in the fundamental node distribution model. In conclusion, SPS-NOMA is expected to be the next generation sidelink C-V2X as the extended mode 4.

Study Electron Cyclotron Double Mode Conversion in Overdense Plasma

Double mode conversion from ordinary mode O to extraordinary mode X is used to achieve electron Bernstein wave (EBWs) for the electron cyclotron resonance heating (ECRH). The efficiency of the mode conversion depends on many parameters including the density gradient Ln, magnetic field source B0 and optimum launching angle Nz. An analytical formalism together with a numerical computation have been employed, considering W7X stellarator main parameters, such as 140 GHz, k0 = 29 cm−1, 2.5 T and 2.4 ×1020 m−3, in order to investigate the efficiency of the mode conversion. The values of the density gradient Ln, obtained by numerical simulation, are from 1 to 10 cm. These values of Ln correspond to the power transmission window TOSX from 88 to 29%. Moreover, the dispersion relation of the EBW mode propagation up to 10 harmonics, ω = 10ωce, has been plotted to help a better visualization of the EBW mode heating. Finally, the power deposition profiles around the resonance layers were calculated and presented.

Deflection of a reflected intense circularly polarized light beam induced by asymmetric radiation pressure.

A deflection effect of an intense laser beam with spin angular momentum is revealed theoretically by an analytical modeling using radiation pressure and momentum balance of laser plasma interaction in the relativistic regime as a deviation from the law of reflection. The reflected beam deflects out of the plane of incidence with a deflection angle up to several milliradians, when a nonlinear polarized laser, with the intensity I_{0}∼10^{19}W/cm^{2} and duration around tens of femtoseconds, is obliquely incident and reflected by an overdense plasma target. This effect originates from the asymmetric radiation pressure caused by spin angular momentum of the laser photons. The dependence of the deflection angle of a Gaussian-type laser on the parameters of laser pulse and plasma foil is theoretically derived, which is also confirmed by three-dimensional particle-in-cell simulations of circularly polarized laser beams with the different intensity and pulse duration.

Electron heating of over-dense plasma with dual-frequency electron cyclotron waves in fully non-inductive plasma ramp-up on the QUEST spherical tokamak

A 28 GHz system with a high-power gyrotron tube has been used for the QUEST spherical tokamak to form an over-dense plasma for electron Bernstein wave (EBW) heating and current drive with an 8.2 GHz-wave. Non-inductive high-density plasma ramp-up experiments with dual-frequency (dual-f ) electron cyclotron (EC) (8.2 GHz and 28 GHz) waves were conducted. A spontaneous density jump (SDJ) to an over-dense state was first observed as a bifurcation phenomenon in the dual-f wave experiment. The over-dense plasma on the 8.2 GHz wave was non-inductively ramped up to 25 kA, and was maintained for 0.4 s under stable plasma equilibrium after two such jumps in one shot. Heating to mildly energetic electrons and bulk electrons was observed even in the over-dense region. The electrostatic EBW heating effect on the mildly energetic electrons in the over-dense region is assessed following a dispersion analysis of the 8.2 GHz wave. The bulk electron heating effect observed is explained as heat exchange from mildly energetic electrons heated by the electrostatic EBW. Remarkably, a high hard-x-ray-radiation temperature of ∼500 keV was also observed in tangential viewing for current-carrying electrons in the over-dense core region. Synergetic heating from the overlap of different 28 GHz EC harmonic resonances as well as higher harmonic heating is discussed for maintaining the highly energetic electrons in the over-dense core region. In addition, the SDJ process and mechanism are considered based on the discussion of the electron heating effects with the 8.2 GHz wave.

Thermal Bremsstrahlung of Local Sources Over Solar Spots Based on Microwave Observations

The paper presents the results of a study of microwave thermal bremsstrahlung of local sources above sunspots. Special attention is paid to the transition from thermal bremsstrahlung to the dominant gyroresonance radiation in the high-frequency part of the spectrum of 12–20 GHz (1.5–2.5 cm). At high frequencies, for which the magnitude of the magnetic field is not enough to generate gyroresonance radiation, thermal bremsstrahlung is the main factor. The presented calculations demonstrate an increase in brightness in an extraordinary mode and a decrease in its intensity in an ordinary mode, as well as corresponding examples of observations. The possibilities and advantages of determination of the field with one polarization corresponding to ordinary radiation are revealed. The studied spectral-polarization features of the radiation, estimates of the effective radiation height, and the characteristic features of the change in the sizes of sources with the wave frequency will make it possible to correctly interpret the observations and to improve the accuracy of magnetic field measurement and the diagnostics of the transition region temperature.

Numerical investigation on special modes with narrow amplification diagram in harbor oscillations

In the studies of harbor oscillations, some modes with extremely narrow amplification diagram are significantly common. An extended mild-slope equation and a fully nonlinear Boussinesq equation are used to study those modes (termed as extreme modes in this paper). The difference between the extreme modes for various harbor shapes, the influence of nonlinearity, and the formation mechanism is comprehensively investigated. The obtained results show that the entrance width has a significant effect on extreme modes, which causes a variation in the extreme modes for different harbor shapes. The smaller a harbor entrance is, the more severe the response of the extreme modes will be. Wave nonlinearity can mitigate the response of extreme modes significantly by transporting the energy to superharmonic components, thereby reducing the time required to reach a steady state. The wave energy inside the harbor increases very slowly because of the unusually weak flow field through the entrance excited by the extreme modes, thus resulting in an exceedingly long time required for the development of the extreme modes. Only a few special wave frequencies can result in such a flow field. Therefore, for extreme modes, the widths of their resonant peaks in the amplification diagram are narrow. Hence, extreme modes can have a significant effect on the harbor only under remarkably ideal conditions. During the plan-shape design of a harbor based on numerical simulation, attention can be focused on ordinary modes, and extreme modes can be ignored to a certain extent.

Ultrafast wave-particle energy transfer in the collapse of standing whistler waves.

Efficient energy transfer from electromagnetic waves to ions has been demanded to control laboratory plasmas for various applications and could be useful to understand the nature of space and astrophysical plasmas. However, there exists the severe unsolved problem that most of the wave energy is converted quickly to electrons but not to ions. Here, an energy-to-ion conversion process in overdense plasmas associated with whistler waves is investigated by numerical simulations and a theoretical model. Whistler waves propagating along a magnetic field in space and laboratories often form standing waves by the collision of counter-propagating waves or through the reflection. We find that ions in standing whistler waves acquire a large amount of energy directly from the waves over a short time scale comparable to the wave oscillation period. The thermalized ion temperature increases in proportion to the square of the wave amplitude and becomes much higher than the electron temperature in a wide range of wave-plasma conditions. This efficient ion-heating mechanism applies to various plasma phenomena in space physics and fusion energy sciences.

Real-time multi-threaded reflectometry density profile reconstructions on COMPASS Tokamak

In COMPASS tokamak, the ordinary mode (O-mode) microwave reflectometry diagnostic has been equipped with an upgraded acquisition system and dedicated computational node running the Multi-Threaded Application Real-Time executor (MARTe). This upgrade aims at the deployment of a real-time (RT) plasma position reflectometry (PPR) diagnostic system for future application in closed-loop plasma position control experiments. The system is synchronized with COMPASS MARTe main controller slow cycle, running at 500 μs, and allows a maximum measurement delivery latency of 450 μs. The RT signal processing algorithms, used to reconstruct the O-mode density profiles are the most time consuming step in the control cycle. This is due to the computation of a large number of Fast Fourier Transforms (FFT) over long data arrays, produced for each reflectometry profile measurement. MARTe is a software control framework that allows the integration of external C/C++ libraries and code such as the FFTW3 C library, a highly optimized and performant implementation of the FFT algorithm into the real-time designs. The framework also provides a set of tools to handle the execution of parallel threads, which can be used to expedite the execution of computationally demanding signal processing algorithms. Herein, we present the processing architecture implemented for the multi-threaded reflectometry density profile reconstruction on MARTe framework, using the FTTW3 library. Consistent systematic results have shown that the implemented solution satisfies COMPASS slow control cycle maximum data latency requirement. Moreover, the obtained reduced latency opens the possibility to either increase the number of processed measurements, leading to a more robust plasma position estimate or even to provide multiple position measurements during each control cycle.

Higher-order harmonic generation of laser radiation due to relativistic plasma resonance at nonrelativistic laser intensity

The well-known plasma resonance (transformation into plasma waves) at a critical density in an inhomogeneous plasma easily becomes relativistic nonlinear even at nonrelativistic laser intensities because the generated electrostatic field is significantly increased. Therefore, the widely used theory of harmonic generation by plasma resonance in a laser-produced plasma should be re-examined. We formulate the corresponding analytical theory of higher-order harmonic generation by nonrelativistic intense laser radiation propagating in a spatially inhomogeneous plasma. We find the spectral and angular characteristics of the harmonic radiation field and demonstrate the role of relativistic nonlinearity at plasma resonance in forming the harmonic spectra. The applicability range of the developed theory is determined by the plasma wave-breaking condition in the vicinity of the critical plasma density, which we analyze explicitly. The proposed theory is compared with the standard perturbation approach. Because the latter corresponds to low laser intensities, this comparison clearly shows the failure of the theory of harmonic generation via linear plasma resonance. The presented relativistic theory, which is applicable up to the laser intensity corresponding to plasma wave breaking, demonstrates the formation of a smooth power-law energy spectrum of higher-order laser harmonics in contrast to the standard perturbation theory. A spectral modulation of harmonics is also shown, which is a unique feature of relativistic nonlinearity.

Investors Perception towards Investments in Derivatives

The most significant aspect of derivatives is risk management not about the elimination of risk. For Conducting ordinary mode of business operations financial derivatives affords a powerful tool for limiting risks to the investors. There are various derivative instruments like index futures. Stock futures, index option, stock options, interest rate futures, currency option, currently traded in these exchanges. The derivative investors ought to perceive the market trend, market reforms, government policies, market regulations; factors influencing derivatives investment [Motivating Factors], return, investment opportunities obviously and adequately take prudent investment decisions. The present study investigates the investors perception towards investments in the derivatives market at Hyderabad region. The data were collected through questionnaire survey from 322 respondents in Hyderabad region.

Investors Perception towards Investments in Derivatives

The most significant aspect of derivatives is risk management not about the elimination of risk. For Conducting ordinary mode of business operations financial derivatives affords a powerful tool for limiting risks to the investors. There are various derivative instruments like index futures. Stock futures, index option, stock options, interest rate futures, currency option, currently traded in these exchanges. The derivative investors ought to perceive the market trend, market reforms, government policies, market regulations; factors influencing derivatives investment [Motivating Factors], return, investment opportunities obviously and adequately take prudent investment decisions. The present study investigates the investors perception towards investments in the derivatives market at Hyderabad region. The data were collected through questionnaire survey from 322 respondents in Hyderabad region