Fast Wave Research Articles

Finite elements method based ICRF waves heating simulation integrating with SOL plasma for EAST tokamak

Abstract Ion cyclotron range of frequency (ICRF) waves heating simulation is often carried out in the core plasma region. However, the inclusion of scrape-off layer (SOL) plasma in the simulation model may lead to new physical phenomenon and needs to be studied. In this paper, we apply finite elements method (FEM) based on the approach of [Vallejos 2019], to simulate ICRF waves heating in account of the realistic SOL plasma for EAST tokamak. In the presence of density pedestal near last closed flux surface (LCFS), a kind of cavity mode is observed for the case of low parallel wave number. Near ion-ion hybrid resonance (IIR) layer in SOL region, mode conversion from fast waves to slow waves takes place. ICRF waves coupling characteristics are roughly consistent with the prediction of the dispersion relation except for some small deviations, which may be caused by fast waves reflection in the high field side. Approximate on axis heating of minority H is observed and power deposition zone broadens with parallel wave number increasing. Waves energy dissipation in SOL plasma is less than 7% and localized near IIR region. Furthermore, the comparison between D(H) and D(He-3) minority heating scenarios is also carried out. The results and conclusions in this paper can provide theoretical reference to ICRF heating experiments and may supply a new insight in ICRF waves form in the plasma edge.

NSTX-U theory, modeling and analysis results

Abstract The mission of the low aspect ratio spherical tokamak NSTX-U is to advance the physics basis and technical solutions required for optimizing the configuration of next-step steady-state tokamak fusion devices. NSTX-U will ultimately operate at up to 2 MA of plasma current and 1 T toroidal field on axis for 5 seconds, and has available up to 15 MW of Neutral Beam Injection (NBI) power at different tangency radii and 6 MW of High Harmonic Fast Wave (HHFW) heating. With these capabilities NSTX-U will develop the physics understanding and control tools to ramp-up and sustain high performance fully non-inductive plasmas with large bootstrap fraction and enhanced confinement enabled via the low aspect ratio, high beta configuration. With its unique capabilities, NSTX-U research also supports ITER and other critical fusion development needs. Super-Alfvénic ions in beam-heated NSTX-U plasmas access energetic particle parameter space that is relevant for both -heated conventional and low aspect ratio burning plasmas. NSTX-U can also generate very large target heat fluxes to test conventional and innovative plasma exhaust and plasma facing component (PFC) solutions. This paper summarizes recent analysis, theory and modelling progress to advance the tokamak physics basis in the areas of macrostability and 3D fields, energetic particle stability and fast ion transport, thermal transport and pedestal structure, boundary and plasma material interaction, RF heating, scenario optimization and real-time control.

Venus mountain waves in the upper atmosphere simulated by a time-invariant linear full-wave spectral model

A 2-D spectral full-wave model is described that simulates the generation and propagation of mountain waves over idealized topography in Venus' atmosphere. Modeled temperature perturbations are compared with the Akatsuki observations. Lower atmosphere eddy diffusivity and stability play a major role in the upward propagation of gravity waves from their mountain sources. Two local times (LT) are considered. For LT = 11 h the waves are blocked by a critical level near 100 km altitude, while for LT = 16 h the waves propagate into the thermosphere. As a result of the small scale height in the Venus thermosphere, for LT = 16 h wave amplitudes grow with increasing altitude up to ~200 km, despite the increasing kinematic viscosity. Although wave amplitudes can become very large in the thermosphere, the value of the total potential temperature gradient suggests that some of these fast waves having extremely large vertical wavelengths may remain convectively stable. Our simulations suggest that the momentum and thermal forcing of the mean state due to the dissipating waves may, at times, be extremely large in the thermosphere. At a given local time, the maximum forcing of the mean state always occurs at an altitude determined by the mean winds and the upper atmospheric viscosity. The surface conditions that determine the forcing (mountain parameters, surface mean wind, eddy diffusivity, and static stability) have little impact on this altitude, but they do significantly impact the magnitude of the forcing.

Theoretical studies of low and high frequency electrostatic solitary waves in the magnetopause associated with asymmetric magnetic reconnection

In a comprehensive analysis of Cluster data, Graham et al. (2015) have reported the existence of slow and fast electrostatic solitary waves (ESWs) associated with asymmetric magnetic reconnection arising from the merger of the magnetic fields, and mixing, of the hot tenuous magnetospheric plasma and the cooler dense magnetosheath plasma. Their analysis also reveals the presence of four electron species, two background Maxwellian distributions and a pair of counter-streaming electron beams. Using the measured plasma parameters and a plasma model consistent with the observations, together with an ion component for charge neutrality, we use fluid dynamic theory in an attempt to identify the plasma modes associated with the ESWs, as well as the polarity and admissible range in speed of the fast and slow structures. It can be inferred from the data sets in Figure 4 in Graham et al. (2015) obtained during the crossing of the Cluster satellites C3 and C4 of the separatrix near the ion diffusion region that the distributions of the two counterstreaming electron beams vary from having identical characteristics to showing small differences over the period during which the ESWs were observed. Accordingly, we align the theoretical parameters in our study with Cluster observations by considering the effect of identical and non-identical counterstreaming electron beam distributions on the existence of ESWs.

A Planar Acoustic Field Reconstruction Method Based on Fast Wave Superposition Spectrum and Sparse Sampling

Based on the fast Fourier wave superposition spectrum method, a new equivalent source method (ESM) with a sparse sampling technique is proposed. First, the equivalent source intensities are expanded on a rectangular virtual surface using a bidirectional Fourier series, resulting in a semi-analytic and half-numerical acoustic pressure expression. The Fourier coefficients result in good sparsity for continuous acoustic pressures from structural vibration sources, and the proposed sparse sampling method can further reduce correlation in the measurement matrix. Better results can be obtained by solving the l1 norm optimization problem. Finally, the method was verified using several examples. The proposed method offers two main advantages compared with the traditional compressive equivalent source method: (1) the unknown source intensity vector is expanded into a bidirectional Fourier series, thereby transforming an unknown source intensity vector into a sparse Fourier coefficient vector, which has better sparsity; (2) the proposed method constructs a random sampling matrix, which is expanded into a sparse sampling matrix by random distribution, thereby improving the reconstruction accuracy of planar near-field acoustic field compared with the traditional random position sampling method reducing correlation in the transfer matrix.

Persistent fast kink magnetohydrodynamic waves detected in a quiescent prominence

Small-scale, cyclic, transverse motions of plasma threads are usually seen in solar prominences, which are often interpreted as magnetohydrodynamic (MHD) waves. Here, we observed small-scale decayless transverse oscillations in a quiescent prominence, and they appear to be omnipresent. The oscillatory periods of the emission intensity and a proxy for the line-of-sight Doppler shift are about half period of the displacement oscillations. This feature agrees well with the fast kink-mode waves in a flux tube. All the moving threads oscillate transversally spatially in phase and exhibit no significant damping throughout the visible segments, indicating that the fast kink MHD waves are persistently powered and ongoing dissipating energy is transferred to the ambient plasma in the quiet corona. However, our calculations suggest that the energy taken by the fast kink MHD waves alone can not support the coronal heating on the quiet Sun.

Observation of a transition to a localized ultrasonic phase in soft matter

Anderson localization arises from the interference of multiple scattering paths in a disordered medium, and applies to both quantum and classical waves. Soft matter provides a unique potential platform to observe localization of non-interacting classical waves because of the order of magnitude difference in speed between fast and slow waves in conjunction with the possibility to achieve strong scattering over broad frequency bands while minimizing dissipation. Here, we provide long sought evidence of a localized phase spanning up to 246 kHz for fast (sound) waves in a soft elastic medium doped with resonant encapsulated microbubbles. We find the transition into the localized phase is accompanied by an anomalous decrease of the mean free path, which provides an experimental signature of the phase transition. At the transition, the decrease in the mean free path with changing frequency (i.e., disorder strength) follows a power law with a critical exponent near unity. Within the localized phase the mean free path is in the range 0.4–1.0 times the wavelength, the transmitted intensity at late times is well-described by the self-consistent localization theory, and the localization length decreases with increasing microbubble volume fraction. Our work sets the foundation for broadband control of localization and the associated phase transition in soft matter, and affords a comparison of theory to experiment.

Resonant wave–filament interactions as a loss mechanism for HHFW heating and current drive

Perkins et al (2012 Phys. Rev. Lett. 109 045001) reported unexpected power losses during high harmonic fast wave (HHFW) heating and current drive in the National Spherical Torus Experiment (NSTX). Recently, Tierens et al (2020 Phys. Plasmas 27 010702) proposed that these losses may be attributable to surface waves on field-aligned plasma filaments, which carry power along the filaments, to be lost at the endpoints where the filaments intersect the limiters. In this work, we show that there is indeed a resonant loss mechanism associated with the excitation of these surface waves, and derive an analytic expression for the power lost to surface wave modes at each filament.

Development and testing of prototype interdigital TWA for fast wave current drive in SST-1 tokamak

Fast Wave Current Drive (FWCD) has the potential to drive non-inductive current in high beta plasmas. A novel interdigital type Travelling Wave Antenna (TWA) was proposed by the authors to launch fast waves inside SST-1 plasma at an operating frequency of 500 MHz and a parallel refractive index of 4.0. A prototype interdigital TWA has been fabricated and tested for its RF response at low power. The simulated and measured frequency responses with vacuum loading are in excellent agreement and the TWA exhibits band-pass like characteristics with a return loss of > 25 dB and insertion loss of 0.45 dB to 1.0 dB. Measurement studies have also been carried out with saltwater loading for various gaps between antenna mouth and saltwater edge and with different conductivity in water. Simulated and measured results are found to be in good agreement with saltwater loading as well. The n∥ spectrum is also measured and it has been observed that n∥ spectrum peaks at a value of 4.0.

Therapeutic Benefits of Short-Arm Human Centrifugation in Multiple Sclerosis-A New Approach.

Short-arm human centrifugation (SAHC) is proposed as a robust countermeasure to treat deconditioning and prevent progressive disability in a case of secondary progressive multiple sclerosis. Based on long-term physiological knowledge derived from space medicine and missions, artificial gravity training seems to be a promising physical rehabilitation approach toward the prevention of musculoskeletal decrement due to confinement and inactivity. So, the present study proposes a novel infrastructure based on SAHC to investigate the hypothesis that artificial gravity ameliorates the degree of disability. The patient was submitted to a 4-week training programme including three weekly sessions of 30 min of intermittent centrifugation at 1.5–2 g. During sessions, cardiovascular, muscle oxygen saturation (SmO2) and electroencephalographic (EEG) responses were monitored, whereas neurological and physical performance tests were carried out before and after the intervention. Cardiovascular parameters improved in a way reminiscent of adaptations to aerobic exercise. SmO2 decreased during sessions concomitant with increased g load, and, as training progressed, SmO2 of the suffering limb dropped, both effects suggesting increased oxygen use, similar to that seen during hard exercise. EEG showed increased slow and decreased fast brain waves, with brain reorganization/plasticity evidenced through functional connectivity alterations. Multiple-sclerosis-related disability and balance capacity also improved. Overall, this study provides novel evidence supporting SAHC as a promising therapeutic strategy in multiple sclerosis, based on mechanical loading, thereby setting the basis for future randomized controlled trials.

Граничная задача для плоских нелинейных уединённых волн в холловской МГД

The equations for plane nonlinear traveling waves in the Hall MHD are derived. The first integral of the “energy” of the equations of traveling waves is obtained and their Hamiltonian property in Lagrangian coordinates is proved. A classification of singular points of the equations of traveling waves is carried out. For an isothermal plasma resting at infinity, the boundary problem of finding plane solitary waves whose parameters have given values at infinity and propagating through space with a given phase velocity is also posed. The ranges of change in the phase velocity are analytically found for which the boundary value problem is solvable. It is shown that there are two families of solutions to the boundary value problem, which differ in the magnitude of the phase velocity – fast waves, the phase velocity of which is greater than the sonic one, and slow waves with a phase velocity less than the sonic one. The solitary waves found were verified by substituting them into the Hall MHD equations.

Neutrino beam driven instability of magnetosonic waves in the presence of oblique magnetic field and ion-neutral collisional effect in plasmas

The neutrino beam driven instability of fast and slow magnetosonic waves with oblique applied magnetic field in multi-component ion, electron and neutrino beam plasma is studied. The dissipation effects of ion-neutral collisions are also included in the model. The neutrino and electron interactions through electro-weak force are included. It is found that the dissipation of ion collisions has significant effect on the phase velocity of the wave propagation and growth rate of the neutrino beam driven instability. The analytical expression of the growth rate of the fast and slow magnetosonic waves instability is found under the weak neutrino beam approximation and in the absence of ions and neutrals (atoms) collision effect. The numerical illustration of growth rates of the fast and slow magnetosonic waves are also presented with variations of magnetic field angle, neutrino beam energy, neutrino beam density, magnetic field intensity. It is found that the growth rate of the fast magnetosonic wave is maximum in case of the perpendicular directed magnetic field to the direction of wave propagation, while growth rate of slow magnetosonic wave is minimum in that case. It is also noticed that growth rate of fast magnetosonic wave comes out to be larger (of the order tens) than the slow magnetosonic wave case, which is quite different from earlier published results of Type II core-collapse supernova.

Propagation of the Alfvén Wave and Induced Perturbations in the Vicinity of a 3D Proper Magnetic Null Point

Abstract The aim of the present work is to study the propagation of the Alfvén wave around a 3D proper magnetic null point and its accompanying perturbations. In this line, the shock-capturing Godunov-type PLUTO code is used to solve the magnetohydrodynamic (MHD) equations. It is found that the Alfvén wave propagates toward the null point at the fan plane and the wave−wave interaction could be the main reason for the Alfvén wave energy dissipation, ehile, at two other planes including the spine axis, the Alfvén wave spreads toward the spine axis and accumulates along it. Furthermore, the fast magnetoacoustic wave moves toward the null point at the fan plane and also at two other planes including the spine axis. The fast magnetoacoustic wave also refracts around the null point without any significant accumulation along the spine axis. Finally, the slow mode moves toward the null point at the fan plane. It is illustrated that, at the x,z plane, in addition to the refraction of the slow wave around the null point, there is an accumulation of the slow mode along the spine axis, while, at the other plane including the spine axis, the slow magnetoacoustic wave refracts around the null point. Moreover, it is found that the 3D structure results in the high amplitude of MHD wave energy in comparison with the 2.5D structure. Finally, it is found that the Alfvén wave gives its energy to the induced fast and slow magnetoacoustic waves and they have more time to heat the plasma.

Analysis by Asymptotic Boundary Conditions of Strip-Grated Dielectric Pipe Over Dielectric Rod With Wide Total Band-Gap as Multifrequency Cylindrical Leaky-Wave Antennas

In this paper, the method of classical vector potential analysis along with the asymptotic strips boundary conditions (ASBC) is used to treat conducting strip grated dielectric pipes wrapped over core dielectric cylindrical rods. By virtue of the periodically-textured surface, this structure is able to exhibit plasmonic behaviors that facilitate strong surface field localization and wave propagation, thereby offering itself as cylindrical surface-wave waveguides or antennas. It can also be configured to exhibit electromagnetic band-gap (EBG) properties, yielding what is known as cylindrical EBG structures. As opposed to a typical counterpart whose core rod is instead conducting, the core dielectric is herein demonstrated to be vital in realizing wide total band-gaps in which neither slow surface nor fast space waves exist, something that the conducting core rod version is incapable of, being only able to offer surface-wave band-gaps, as do many others in the literature that have neglected the suppression of fast space waves as well. By coaxially connecting various such rod structures, each with its own distinct total band-gap, multi-frequency, multi-functional cylindrical antennas with mitigated inter-band interference even under simultaneous operations can be achieved when the pass-band of any one rod (in which its operating frequency lies) falls within the total band-gaps of all others, as herein investigated. Manufactured prototypes are also measured, yielding experimental results that agree well with theoretical predictions.

S-wave anisotropy from two dipole sonic data processing methods, confronted with fracture permeability, logs and cores

The present paper consists in two parts, determined by the historical emerging production of Dipole Sonic Imager (DSI) measurements and results in the early 1990’s. The DSI data were processed following two methods simultaneously developed in France and in USA by Schlumberger. In the first part the early dipole sonic S-wave velocity results obtained in late 1993 are confronted with the other borehole data obtained in the scientific borehole MM-1, entirely cored and extensively logged, as part of the comprehensive scientific project named Géologie Profonde de la France (GPF), conducted by the Bureau de Recherches Géologiques et Minières (BRGM, i.e. the French Geological Survey), in Ardèche, southern France. In 1994, José Perrin summarized and integrated all the borehole information including the preliminary results from an azimuthal “rotation scan” of S-wave sonic slowness determination method quickly developed in Schlumberger-France and aiming at detecting only the presence of S-wave velocity anisotropy in a first step. The initial results were presented to the French industrial logging community in April 1994, prior to the commercialization of any S-wave splitting computer detection routine applied to dipole sonic data. The second part focuses on the comparison of the dipole sonic S-wave anisotropy detection results from two methods produced at a later time by Schlumberger, namely: a) results from the commercial S-wave anisotropy detection routine based on cross energy minimization, obtained in October 1994, and b) principal S-wave azimuth results sorted from the “rotation scan” azimuthal method, produced in 1995 and further improved in July 1997. After discussing the discrepancies of the principal fast S-wave azimuth derived from the two methods with diverse specialists in Schlumberger, over several years, and on a spare time basis, the authors expose constructive explanations in the present paper. A limited overview of the latest dipole sonic data processing developments has also been attempted to better understand the differing S-wave birefringence results obtained in MM-1, suggesting that the rock formation in the immediate borehole vicinity, up to three times the borehole radius, may not be homogeneous along the borehole depth depending on the local geological context. Besides, the Fast Azimuth split S-wave (FAZ) fits with the strike of major regional faults and parallel to the maximal horizontal palaeo-stress, which happens to be nearly orthogonal to the local present stress direction accepted by the geologists! The present case study suggests that the S-wave anisotropy results ought to become more reliable, mainly on the accuracy and precision of the FAZ. Additionally, the efficiency of the semblance parameter for S-wave attenuation anisotropy detection is pondered, where no S-wave velocity anisotropy is detected over the dipole sonic receiver array.

COMPOUND HETEROZYGOTE REASON FOR JUVENILE FORM OF TAY-SACHIS DISEASE -CASE REPORT

Tay-Sachs diseases are group of rare autosomal recessive lysosomal disorders, GM2-gangliozidoses. They are progressive neurodegenerative diseases, caused by a mutation in the enzyme β-hexosaminidase A. Depending on the time of presentation of symptoms, there are three forms: infantile, juvenile and adult. We present a 8 year old patient, who is presented at the age of 4 with progressive deterioration in psychomotor and speech skills, pyramidal symptoms, ataxia and muscle weakness. The EEG showed bihemispheric fast spike waves and the MRI showed no findings of organic disease. Finally a molecular genetic testing was made, which proved the diagnosis of juvenile form of Tay-Sachs disease. It was determined that the patient is a compound heterozygote, with two different mutations in the alleles of the HEXA gene, one  inherited from the mother and the other one from the father. The juvenile Tay-Sachs disease is characterized with beginnig between the age of 2 to 10 years old. Clinically it is presented with muscle weakness, incoordination, ataxia, dysarthria, dysphagia and progressive spasticity. It progresses to development of dementia, convulsions, blindness and vegetative state with decerebrate rigidity and death by the age of 15. It is inherited autosomal recessive with one mutation present on both alleles of the HEXA gene. Treatment options for Tay-Sachs disease currently are only symptomatic and supportive. There are ongoing researches for curative treatments for Tay-Sachs, like enzyme replacement, chaperone, substrate reduction and gene therapy. Keywords: Tay-Sachs disease, juvenile form, compound heterozygote.  

Parametrization of suppressing hypersonic second-mode waves by transverse rectangular microgrooves

Aiming at delaying boundary-layer transition of hypersonic vehicles, the second-mode wave in the boundary layer of a Mach 6 flat plate is studied. Linear stability theory (LST) and direct numerical simulations (DNS) are used to investigate the discrete modes and the relation between the suppressing effect of second-mode wave and the location of transverse rectangular micro-groove (0.4 mm in width), respectively. The LST results show that vortex/entropy waves cause the branch types of Mack’s second mode and “mode I” modes (usually derived from fast acoustic waves) to change. The DNS results show that the influence of the grooved surface on the base flow depends on the streamwise location (or boundary-layer thickness). As the grooved surface shifts backward (or thickness increases), the influence of intensity on the base flow decreases, and the friction resistance coefficient <inline-formula><tex-math id="M1">\begin{document}$ C{d_{\text{f}}} $\end{document}</tex-math><alternatives><graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="19-20220851_M1.jpg"/><graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="19-20220851_M1.png"/></alternatives></inline-formula>, differential pressure resistance coefficient <inline-formula><tex-math id="M2">\begin{document}$ C{d_{\text{p}}} $\end{document}</tex-math><alternatives><graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="19-20220851_M2.jpg"/><graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="19-20220851_M2.png"/></alternatives></inline-formula> and total resistance coefficient <inline-formula><tex-math id="M3">\begin{document}$ C{d_x} $\end{document}</tex-math><alternatives><graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="19-20220851_M3.jpg"/><graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="19-20220851_M3.png"/></alternatives></inline-formula> of the grooved surface also decrease. It is found that the grooves located in front of the synchronization region of the fast mode and slow mode still have an inhibitory effect on the second-mode wave, which is different from the effect of small-sized (micrometer scale) micro-pores reported in the literature. It is also found that the suppression effect on the second-mode wave is best when the grooves are arranged in the vicinity of the maximum growth-rate point or at the location of the synchronization interval of the fast mode and slow mode.

Uncertainty quantification in a mechanical submodel driven by a Wasserstein-GAN

The analysis of parametric and non-parametric uncertainties of very large dynamical systems requires the construction of a stochastic model of said system. Linear approaches relying on random matrix theory Soize (2000) and principal component analysis can be used when systems undergo low-frequency vibrations. In the case of fast dynamics and wave propagation, we investigate a random generator of boundary conditions for fast submodels by using machine learning. We show that the use of non-linear techniques in machine learning and data-driven methods is highly relevant.Physics-informed neural networks Raissi et al. (2017) are a possible choice for a data-driven method to replace linear modal analysis. An architecture that supports a random component is necessary for the construction of the stochastic model of the physical system for non-parametric uncertainties, since the goal is to learn the underlying probabilistic distribution of uncertainty in the data. Generative Adversarial Networks (GANs) are suited for such applications, where the Wasserstein-GAN with gradient penalty variant Gulrajani et al. (2017) offers improved convergence results for our problem.The objective of our approach is to train a GAN on data from a finite element method code (Fenics) so as to extract stochastic boundary conditions for faster finite element predictions on a submodel. The submodel and the training data have both the same geometrical support. It is a zone of interest for uncertainty quantification and relevant to engineering purposes. In the exploitation phase, the framework can be viewed as a randomized and parametrized simulation generator on the submodel, which can be used as a Monte Carlo estimator.

Use of the Normalized Design Parameters for Designing a Strip Speaker Operated by the Traveling-Wave Control Method

A strip speaker is the simplified panel speaker adopting a thin beam as the radiator, which is operated under the traveling-wave control method (TCM) with three actuators. The structural resonances are suppressed fundamentally by nullifying the reflected bending waves near the boundary, thus radiating a smooth sound spectrum in a wide frequency band. This study develops the design guidelines for such TCM-controlled strip speakers by investigating the effect of design variables on acoustic performances, such as the effective frequency range and the radiation efficiency. To this end, the acoustic performances are normalized by the size and physical properties of the beam so that a parametric study in the normalized domain can generalize the conditions for the desired acoustic performances. The result shows that the effective frequency range becomes wider when the beam material has a fast wave speed, and the radiation efficiency is enhanced as the beam density decreases. It is found that the two acoustic performances require a trade-off in selecting the actuator location and beam thickness. The suggested design procedure is validated using acrylic and aluminum beams having the same size. The aluminum beam has a faster wave speed, thus covering the effective bandwidth of 5800 Hz, 2.5 times wider than the acrylic case. On the other hand, the acrylic beam has five times higher radiation efficiency due to its low density. As a result, one can select the dimension and material of the beam appropriately to achieve the desired acoustic performance by using the suggested design method.

Full-wave 2D modeling of helicons propagation and absorption in thespherical tokamak Globus-M2

Numerical modeling of propagation and absorption of fast waves(helicons) with frequency 200 MHz in 2D inhomogeneous plasma of thespherical tokamak Globus-M2 was carried out with 2D full-wave code. Toroidal effects, poloidal magnetic field and the actual shape of the fluxsurfaces were taken into account. The full wave electric field and RF powerabsorption profiles were computed by solving plasma wave equation withelectron Landau damping term. The modeling demonstrated a fairly highefficiency of helicons absorption in the bulk plasma within a wide range ofexperimental parameters. The waves propagate to the inner regions of theplasma column and are mainly absorbed there; less than 20% of RF energyreturns back to the plasma periphery. Keywords: high temperature plasma, nuclear fusion, tokamak, high frequency plasma waves, helicons, plasma wave equation, full-wave code.\