Benchmarking ICRF Full-wave Solvers for ITER
International Nuclear Information System (INIS)
Budny, R.V.; Berry, L.; Bilato, R.; Bonoli, P.; Brambilla, M.; Dumont, R.J.; Fukuyama, A.; Harvey, R.; Jaeger, E.F.; Indireshkumar, K.; Lerche, E.; McCune, D.; Phillips, C.K.; Vdovin, V.; Wright, J.
2011-01-01
Benchmarking of full-wave solvers for ICRF simulations is performed using plasma profiles and equilibria obtained from integrated self-consistent modeling predictions of four ITER plasmas. One is for a high performance baseline (5.3 T, 15 MA) DT H-mode. The others are for half-field, half-current plasmas of interest for the pre-activation phase with bulk plasma ion species being either hydrogen or He4. The predicted profiles are used by six full-wave solver groups to simulate the ICRF electromagnetic fields and heating, and by three of these groups to simulate the current-drive. Approximate agreement is achieved for the predicted heating power for the DT and He4 cases. Factor of two disagreements are found for the cases with second harmonic He3 heating in bulk H cases. Approximate agreement is achieved simulating the ICRF current drive.
Full-wave modeling of ICRF waves: global and quasi-local descriptions
International Nuclear Information System (INIS)
Dumont, R. J.
2007-01-01
Waves in the Ion Cyclotron Range of Frequencies (ICRF) undergo significant space dispersion as they propagate in magnetic fusion plasmas, making it necessary to incorporate non-local effects in their physical description. Full-wave codes are routinely employed to simulate ICRF heating experiments in tokamaks. The vast majority of these codes rely on a description of the plasma based on a 'quasi-local' derivation of the dielectric tensor, i.e. assuming that the range of space dispersion remains small compared to the system dimensions. However, non-local effects caused by wide particle orbits are expected to play a significant role in current and future experiments featuring wave-driven fast ions, fusion-born alpha particles... Global formalisms have thus been proposed to include these effects in a more comprehensive fashion. Based on a description of the particle dynamics in terms of action-angle variables, a full-wave code, named EVE, is currently under development. Its first version, presented here, incorporates quasi-local expressions valid to second order in Larmor radius, derived from the more general Hamiltonian formalism. The obtained tool has the advantage of being compatible with the current requirements of integrated modeling, and lends itself to direct comparisons with existing codes
Full-wave and Fokker Planck analysis of ICRF heating experiments in the Alcator C-Mod tokamak
International Nuclear Information System (INIS)
Bonoli, P.T.; Golovato, S.; Porkolab, M.; Takase, Y.
1996-01-01
The Alcator C-Mod device is a high field, high density, shaped tokamak with parameters a = 0.22 m, R 0 = 0.67 m, B 0 ≤ 9.0 T, κ ≤ 1.8, δ ≤ 0.8, and 1.0 x 10 20 m -3 n e (0) ≤ 1.0 x 10 21 m -3 . Four megawatt of ICRF power is available at 80 MHz. The wide operating range in magnetic field makes several heating schemes possible: (i) Second harmonic heating of hydrogen (f 0 = 2f CH ) at 2.6 T in (D-H); (ii) Fundamental heating of (H) (f 0 = f CH ) at 5.3T in a D-(H) plasma; and (iii) Fundamental heating of ( 3 He) (f 0 = f C 3 He ) at 7.9 T in a D-( 3 He) plasma. The most successful heating regime to date has been (H)-minority heating at 5.3 T. Pellet enhanced performance (PEP) modes have also been achieved in C-Mod in D-(H) at 5.3 T and in D-( 3 He) at 7.9 T, with a combination of intense ICRF heating and Li-pellet injection. A variety of numerical models are used to analyze these heating schemes. A 1-D full-wave code (FELICE) is used to study open-quotes single passclose quotes damping of the ICRF wavefront and damping of mode-converted ion Bernstein waves. A toroidal full-wave code (FISIC) is used to study interference and focussing effects of the ICRF waves as well as damping of the ICRF power upon multiple passes of the ICRF wavefront. A combined bounce averaged Fokker Planck and toroidal full-wave code (FPPRF) is used to study the ion tail formation, orbit losses, and the power partition of the ICRF tail to the background electrons and ions. Full-wave and Fokker Planck analyses confirm the strong single pass absorption of the ICRF power in D-(H) at 5.3 T. Analysis of PEP-mode plasmas in D-( 3 He) indicates improved wave focussing and 3 He-cyclotron absorption of the ICRF waves relative to L-mode. A dramatic increase in the transfer of 3 He tail power to the background deuterium is also found for PEP-mode plasmas
Modeling of EAST ICRF antenna performance using the full-wave code TORIC
Energy Technology Data Exchange (ETDEWEB)
Edlund, E. M., E-mail: eedlund@pppl.gov [Princeton Plasma Physics Laboratory, Princeton, NJ (United States); Bonoli, P. T.; Porkolab, M.; Wukitch, S. J. [MIT Plasma Science and Fusion Center, Cambridge, MA (United States)
2015-12-10
Access to advanced operating regimes in the EAST tokamak will require a combination of electron-cyclotron resonance heating (ECRH), neutral beam injection (NBI) and ion cyclotron range frequency heating (ICRF), with the addition of lower-hybrid current drive (LHCD) for current profile control. Prior experiments at the EAST tokamak facility have shown relatively weak response of the plasma temperature to application of ICRF heating, with typical coupled power about 2 MW out of 12 MW source. The launched spectrum, at n{sub φ} = 34 for 0-π -0-π phasing and 27 MHz, is largely inaccessible at line-averaged densities of approximately 2 × 10{sup 19} m{sup −3}. However, with variable antenna phasing and frequency, this system has considerable latitude to explore different heating schemes. To develop an ICRF actuator control model, we have used the full-wave code TORIC to explore the physics of ICRF wave propagation in EAST. The results presented from this study use a spectrum analysis using a superposition of n{sub φ} spanning −50 to +50. The low density regime typical of EAST plasmas results in a perpendicular wavelength comparable to the minor radius which results in global cavity resonance effects and eigenmode formation when the single-pass absorption is low. This behavior indicates that improved performance can be attained by lowering the peak of the k{sub ||} spectrum by using π/3 phasing of the 4-strap antenna. Based on prior studies conducted at Alcator C-Mod, this phasing is also expected to have the advantage of nearly divergence-free box currents, which should result in reduced levels of impurity production. Significant enhancements of the loading resistance may be achieved by using low k{sub ||} phasing and a combination of magnetic field and frequency to vary the location of the resonance and mode conversion regions. TORIC calculations indicate that the significant power may be channeled to the electrons and deuterium majority. We expect that
ICRF wave propagation and absorption in tokamak and mirror magnetic fields: a full-wave calculation
International Nuclear Information System (INIS)
Jaeger, E.F.; Batchelor, D.B.; Weitzner, H.; Whealton, J.H.
1985-01-01
Global solutions for the ion cyclotron resonant frequency (ICRF) wave fields in a straight tokamak with rotational transform and a poloidally symmetric mirror are calculated in the cold plasma limit. The component of the wave electric field parallel to vector Bis assumed zero. Symmetry in each problem allows Fourier decomposition in one ignorable coordinate, and the remaining set of two coupled, two-dimensional partial differential equations is solved by finite differencing. Energy absorption and antenna impedance are calculated using a simple collisional absorption model. When large gradients in vertical barBvertical bar along vectorB are present in either geometry, ICRF heating at the fundamental ion cyclotron resonance is observed. For the mirror, such gradients are always present. But for the tokamak, the rotational transform must be large enough that vectorB . delB greater than or equal to 0(1). For smaller transforms more typical of real tokamaks, only heating at the two-ion hybird resonance is observed. This suggests that direct resonant absorption at the fundamental ion cyclotron resonance may be possible in stellarators where vectorB . delB approx. 0(1) + 11
ICRF wave propagation and absorption in tokamak and mirror magnetic fields: a full-wave calculation
International Nuclear Information System (INIS)
Jaeger, E.F.; Batchelor, D.B.; Weitzner, H.; Whealton, J.H.
1986-01-01
Global solutions for the ion cyclotron resonant frequency (ICRF) wave fields in a straight tokamak with rotational transform and in a poloidally symmetric mirror are calculated in the cold plasma limit. The component of the wave electric field parallel to B vector is assumed zero. Symmetry in each problem allows Fourier decomposition in one ignorable coordinate, and the remaining set of two coupled, two-dimensional partial differential equations is solved by finite differencing. Energy absorption and antenna impedance are calculated using a simple collisional absorption model. When large gradients in absolute value B along B vector are present in either geometry, ICRF heating at the fundamental ion cyclotron resonance is observed. For the mirror, such gradients are always present. But for the tokamak, the rotational transform must be large enough that B vector . delB greater than or equal to 0(1). For smaller transforms more typical of real tokamaks, only heating at the two-ion hybrid resonance is observed. This suggests that direct resonant absorption at the fundamental ion cyclotron resonance may be possible in stellarators where B vector . delB approx. 0(1) naturally. 13 refs., 23 figs
ICRF Mode Conversion Studies with Phase Contrast Imaging and Comparisons with Full-Wave Simulations
International Nuclear Information System (INIS)
Tsujii, N.; Bonoli, P. T.; Lin, Y.; Wright, J. C.; Wukitch, S. J.; Porkolab, M.; Jaeger, E. F.; Harvey, R. W.
2011-01-01
Waves in the ion cyclotron range of frequencies (ICRF) are widely used to heat toka-mak plasmas. In a multi-ion-species plasma, the FW converts to ion cyclotron waves (ICW) and ion Bernstein waves (IBW) around the ion-ion hybrid resonance (mode conversion). The mode converted wave is of interest as an actuator to optimise plasma performance through flow drive and current drive. Numerical simulations are essential to describe these processes accurately, and it is important that these simulation codes be validated. On Alcator C-Mod, direct measurements of the mode converted waves have been performed using Phase Contrast Imaging (PCI), which measures the line-integrated electron density fluctuations. The results were compared to full-wave simulations AORSA and TORIC. AORSA is coupled to a Fokker-Planck code CQL3D for self-consistent simulation of the wave electric field and the minority distribution function. The simulation results are compared to PCI measurements using synthetic diagnostic. The experiments were performed in D-H and D- 3 He plasmas over a wide range of ion species concentrations. The simulations agreed well with the measurements in the strong absorption regime. However, the measured fluctuation intensity was smaller by 1-2 orders of magnitudes in the weakly abosorbing regime, and a realistic description of the plasma edge including dissipation and antenna geometry may be required in these cases.
Energy Technology Data Exchange (ETDEWEB)
Vdovin V.L.
2005-08-15
In this report we describe theory and 3D full wave code description for the wave excitation, propagation and absorption in 3-dimensional (3D) stellarator equilibrium high beta plasma in ion cyclotron frequency range (ICRF). This theory forms a basis for a 3D code creation, urgently needed for the ICRF heating scenarios development for the operated LHD, constructed W7-X, NCSX and projected CSX3 stellarators, as well for re evaluation of ICRF scenarios in operated tokamaks and in the ITER . The theory solves the 3D Maxwell-Vlasov antenna-plasma-conducting shell boundary value problem in the non-orthogonal flux coordinates ({Psi}, {theta}, {var_phi}), {Psi} being magnetic flux function, {theta} and {var_phi} being the poloidal and toroidal angles, respectively. All basic physics, like wave refraction, reflection and diffraction are self consistently included, along with the fundamental ion and ion minority cyclotron resonances, two ion hybrid resonance, electron Landau and TTMP absorption. Antenna reactive impedance and loading resistance are also calculated and urgently needed for an antenna -generator matching. This is accomplished in a real confining magnetic field being varying in a plasma major radius direction, in toroidal and poloidal directions, through making use of the hot dense plasma wave induced currents with account to the finite Larmor radius effects. We expand the solution in Fourier series over the toroidal ({var_phi}) and poloidal ({theta}) angles and solve resulting ordinary differential equations in a radial like {Psi}-coordinate by finite difference method. The constructed discretization scheme is divergent-free one, thus retaining the basic properties of original equations. The Fourier expansion over the angle coordinates has given to us the possibility to correctly construct the ''parallel'' wave number k{sub //}, and thereby to correctly describe the ICRF waves absorption by a hot plasma. The toroidal harmonics are tightly
ICRF full wave field solution and absorption for D-T and D-3He heating scenarios
International Nuclear Information System (INIS)
Scharer, J.; Sund, R.
1989-01-01
We consider a fundamental power conservation relation, full wave solutions for fields and power absorption in moderate and high density tokamaks to third order in the gyroradius expansion. The power absorption, conductivity tensor and kinetic flux associated with the conservation relation as well as the wave differential equation are obtained. Cases examined include D-T and D- 3 He scenarios for TFTR,JET and CIT at the Fundamental and Second harmonic. Optimum single pass absorption cases for D-T operation in JET and CIT are considered as a function of the K ≡ spectrum of the antenna with an without a minority He 3 resonance. It is found that at elevated temperatures >4 keV, minority (10%) fundamental deuterium absorption is very efficient for either fast wave low or high field incidence or high field Bernstein wave incidence. We consider the effects of a 10 keV bulk and 100 keV tail helium distribution on the second harmonic absorption in a deuterium plasma for Jet parameters. In addition, scenarios with ICRF operation without attendant substantial tritium concentrations are found the fundamental (15%) and second harmonic helium (33%) heating in a the deuterium plasma. For High field operation at high density in CIT, we find a higher part of the K parallel spectrum yields good single pass absorption with a 5% minority helium concentration in D-T
Model for ICRF fast wave current drive in self-consistent MHD equilibria
International Nuclear Information System (INIS)
Bonoli, P.T.; Englade, R.C.; Porkolab, M.; Fenstermacher, M.E.
1993-01-01
Recently, a model for fast wave current drive in the ion cyclotron radio frequency (ICRF) range was incorporated into the current drive and MHD equilibrium code ACCOME. The ACCOME model combines a free boundary solution of the Grad Shafranov equation with the calculation of driven currents due to neutral beam injection, lower hybrid (LH) waves, bootstrap effects, and ICRF fast waves. The equilibrium and current drive packages iterate between each other to obtain an MHD equilibrium which is consistent with the profiles of driven current density. The ICRF current drive package combines a toroidal full-wave code (FISIC) with a parameterization of the current drive efficiency obtained from an adjoint solution of the Fokker Planck equation. The electron absorption calculation in the full-wave code properly accounts for the combined effects of electron Landau damping (ELD) and transit time magnetic pumping (TTMP), assuming a Maxwellian (or bi-Maxwellian) electron distribution function. Furthermore, the current drive efficiency includes the effects of particle trapping, momentum conserving corrections to the background Fokker Planck collision operator, and toroidally induced variations in the parallel wavenumbers of the injected ICRF waves. This model has been used to carry out detailed studies of advanced physics scenarios in the proposed Tokamak Physics Experiment (TPX). Results are shown, for example, which demonstrate the possibility of achieving stable equilibria at high beta and high bootstrap current fraction in TPX. Model results are also shown for the proposed ITER device
Slow wave antenna coupling to ion Bernstein waves for plasma heating in ICRF
International Nuclear Information System (INIS)
Sy, W.N-C.; Amano, T.; Ando, R.; Fukuyama, A.; Watari, T.
1984-10-01
The coupling of ICRF power from a slow wave antenna to a plasma with finite temperature is examined theoretically and compared to an independent computer calculation. It is shown that such antennas can be highly efficient in trasferring most of the antenna power directly to ion Bernstein waves, with only a very small fraction going into fast waves. The potentiality of this coupling scheme for plasma heating in ICRF is briefly discussed. (author)
Tokamak wave coupling and heating in the ICRF
International Nuclear Information System (INIS)
Romero, H.; Scharer, J.; Sund, R.
1983-01-01
The authors consider wave propagation in the vicinity of the Ion Cyclotron Range of Frequencies (ICRF) in general tokamak geometries. The problem of wave coupling by means of waveguides is addressed. In particular, the reflection coefficient for a simple TE 10 waveguide is obtained by taking into account both the z and y spectrum of the launcher. In order to take into account spatial gradients in the plasma medium, they use a one-dimensional slab model of the plasma. Good coupling and heating results are obtained for the first few harmonics for sufficiently weak edge density gradient and > about 1 keV core temperatures. To analyze the heating of the plasma interior in the presence of ICRF, a 2-D differential equation is being developed which takes into account spatial gradients and mode coupling
Alpha-particle simulation using NBI beam and ICRF wave
International Nuclear Information System (INIS)
Ogawa, Y.; Hamada, Y.
1984-07-01
A new idea to produce the distribution function similar to that of alpha-particles in an ignited plasma has been proposed. This concept is attributed to the acceleration of the injected beam up to about 1 MeV/nucleon by the ICRF wave with cyclotron higher harmonics. This new method makes it possible to perform the simulation experiments for alpha-particles under the condition of moderate plasma parameters (e.g., Tsub(e) = 4 keV, nsub(e) = 3.5x10 19 m -3 and B sub(T) = 3 T). And it is found that 3ωsub(ci) ICRF wave is preferable compared with other cyclotron harmonics, from the viewpoints of the effective tail formation with smaller bulk ion heating and lower amplitude of the applied electric field. The formula for the maximum energy of the extended beam is also derived. (author)
Simulations of ICRF-fast wave current drive on DIIID
International Nuclear Information System (INIS)
Ehst, D.A.
1990-06-01
Self-consistent calculations of MHD equilibria, generated by fast wave current drive and including the bootstrap effect, were done to guide and anticipate the results of upcoming experiments on the DIIID tokamak. The simulations predict that 2 MW of ICRF power is more than adequate to create several hundred kiloamperes in steady state; the total current increases with the temperature and density of the target plasma. 12 refs., 12 figs., 1 tab
Global analysis of ICRF wave coupling on Tore Supra
International Nuclear Information System (INIS)
Goniche, M.; Bremond, S.; Colas, L.
2003-01-01
The Tore Supra tokamak is equipped with a multi-megawatt ion cyclotron range of frequency (ICRF) system for heating and current drive. The coupling of the fast wave to the plasma, characterized by the distributed coupling resistance along the radiating straps, is a crucial issue in order to launch large RF powers. Many factors can have an effect on ICRF wave coupling. Quantitative prediction from theoretical modelling requires the knowledge of the local inhomogeneous plasma density profile in front of the antenna for running sophisticated antenna codes. In this work, we have rather followed a 'global' approach, based on Tore Supra experimental results, for the parametric study of the coupling resistance. From a large data base covering seven experimental campaigns (∼2250 shots), a scaling law of the coupling resistance including the main parameters of the plasma and of the antenna configuration is established. This approach is found to be reliable for the analysis of coupling in the different scenarios: He/D 2 gas filling, gas/pellets for plasma fuelling, plasma leaning on inner wall/low field side limiter, limiter/ergodic divertor configuration, minority heating/direct electron heating. From one scenario to another, a significant variation of the coefficients of the scaling law is found. The study of these variations allows to get some insight on the main physical mechanisms which influence the ICRF wave coupling in a tokamak operation, such as the wall conditioning and recycling conditions, RF sheaths or frequency. (author)
Bulk Ion Heating with ICRF Waves in Tokamaks
DEFF Research Database (Denmark)
Mantsinen, M. J.; Bilato, R.; Bobkov, V. V.
2015-01-01
Heating with ICRF waves is a well-established method on present-day tokamaks and one of the heating systems foreseen for ITER. However, further work is still needed to test and optimize its performance in fusion devices with metallic high-Z plasma facing components (PFCs) in preparation of ITER...... when 3 MW of ICRF power tuned to the central 3He ion cyclotron resonance was added to 4.5 MW of deuterium NBI. The radial gradient of the Ti profile reached locally values up to about 50 keV/m and the normalized logarithmic ion temperature gradients R/LTi of about 20, which are unusually large for AUG...
ICRF Traveling Wave launcher for fusion devices
International Nuclear Information System (INIS)
Ragona, R
2017-01-01
Ion Cyclotron Resonance Heating and Current Drive is a method that has the ability to heat directly the ions in the Deuterium-Tritrium fuel to the high temperature needed for the fusion reaction to works. The capability of efficiently couple the Radio Frequency power to the plasma plays a big role in the overall performance of a fusion device. A Traveling Wave Antenna in a resonant ring configuration is a good candidate for an Ion Cyclotron Resonance Heating and Current Drive system. It has the capability to increase the coupled power with respect to present designs and to have a highly selective power spectrum that can be peaked around the maximally absorbed wave. It is also insensitive to the loading variations due to fluctuation of the plasma edge increasing the reliability and the efficiency of the system. It works as a low power density launcher due to the possible large number of current carrying elements. (paper)
International Nuclear Information System (INIS)
Phillips, C.K.
1985-12-01
This lecture provides a survey of the methods used to model fast magnetosonic wave coupling, propagation, and absorption in tokamaks. The validity and limitations of three distinct types of modelling codes, which will be contrasted, include discrete models which utilize ray tracing techniques, approximate continuous field models based on a parabolic approximation of the wave equation, and full field models derived using finite difference techniques. Inclusion of mode conversion effects in these models and modification of the minority distribution function will also be discussed. The lecture will conclude with a presentation of time-dependent global transport simulations of ICRF-heated tokamak discharges obtained in conjunction with the ICRF modelling codes. 52 refs., 15 figs
Resonance absorption of ICRF wave in edge plasma
International Nuclear Information System (INIS)
Sugihara, Ryo; Yamanaka, Kaoru.
1987-07-01
An edge plasma is shown to significantly absorb ICRF wave when a resonant triplet, a cutoff-resonance-cutoff triplet, is constructed in the evanescent region. Two-ion-component plasmas in a torus are considered though the plasmas are modeled by a slab in which the density changes linearly along the x-axis. The resonance is a perpendicular-ion-cyclotron resonance, i.e., an Alfven resonance, and is formed when the applied frequency ω is smaller than the local cyclotron frequency, at the edge of the antenna side, of the lighter species of ions. Roughly the absorption rate A b is given by M 2 for M 2 >> S 2 and S 4 for S 2 >> M 2 where M = k y l and S ≅ k z l and l is a scale length of the order of the plasma minor radius and k y and k z are the perpendicular and the parallel components of the wave vector. It is noted that the both quantities, M and S, readily become of the order of unity. Since A b is not very sensitive to the density ratio of the two ion species, a few percent of impurities may cause a significant absorption. As the mass ratio of the two ion species comes close to unity the triplet forms readily. Therefore a D-T plasma seems to suffer more easily this kind of resonance absorption than a D-H plasma. (author)
Directory of Open Access Journals (Sweden)
Jacquot Jonathan
2017-01-01
Full Text Available A sequence of simulations is performed with RAPLICASOL and SSWICH to compare two AUG ICRF antennas. RAPLICASOL outputs have been used as input to SSWICH-SW for the AUG ICRF antennas. Using parallel electric field maps and the scattering matrix produced by RAPLICASOL, SSWICH-SW, reduced to its asymptotic part, is able to produce a 2D radial/poloidal map of the DC plasma potential accounting for the antenna input settings (total power, power balance, phasing. Two models of antennas are compared: 2-strap antenna vs 3-strap antenna. The 2D DC potential structures are correlated to structures of the parallel electric field map for different phasing and power balance. The overall DC plasma potential on the 3-strap antenna is lower due to better global RF currents compensation. Spatial proximity between regions of high RF electric field and regions where high DC plasma potentials are observed is an important factor for sheath rectification.
Plasma edge modelling with ICRF coupling
Directory of Open Access Journals (Sweden)
Zhang Wei
2017-01-01
Full Text Available The physics of Radio-Frequency (RF wave heating in the Ion Cyclotron Range of Frequencies (ICRF in the core plasmas of fusion devices are relatively well understood while those in the Scrape-Off Layer (SOL remain still unresolved. This paper is dedicated to study the ICRF interactions with the plasma edge, mainly from the theoretical and numerical point of view, in particular with the 3D edge plasma fluid and neutral transport code EMC3-EIRENE and various wave codes. Here emphasis is given to the improvement of ICRF coupling with local gas puffing and to the ICRF induced density convection in the SOL.
Recent progress with ICRF heating on EAST
International Nuclear Information System (INIS)
Zhang Xinjun; Zhao, Y.P.; Mao, Y.Z.
2014-01-01
Radio Frequency (RF) power in the ion cyclotron range of frequencies (ICRF) is one of the primary auxiliary heating techniques for Experimental Advanced Superconducting Tokamak (EAST). The ICRF system for the EAST has been developed to support long-pulse, high-β, advanced tokamak fusion physics experiments. The ICRF system can deliver 12 MW of RF power to the plasma for 1000 seconds through two antennas located in B- and I-ports. Each ICRF transmitter with high power up to 1.5 MW has been successfully tested on a dummy load. The main technical features of the ICRF system is described. Two simulation codes, TORIC (a full wave solver) and SSFPQL (the quasilinear Fokker-Planck solver), are combined to simulate the ICRF heating in the EAST 2D magnetic configuration. The fast wave propagation and absorption characteristics, power partitions among the plasma species and the RF driven energetic tails have been analyzed. (author)
Density convection near radiating ICRF antennas and its effect on the coupling of lower hybrid waves
International Nuclear Information System (INIS)
Ekedahl, A.; Colas, L.; Beaumont, B.; Bibet, Ph.; Bremond, S.; Kazarian, F.; Noterdaeme, J.M.; Tuccillo, A.A.
2003-01-01
Combined operation of lower hybrid (LH) and Ion Cyclotron Resonance Frequency (ICRF) waves can result in a degradation of the LH wave coupling, as observed both in the Tore-Supra and Jet tokamaks. The reflection coefficient on the part of the LH launcher magnetically connected to the powered ICRF antenna increases, suggesting a local decrease in the electron density in the connecting flux tubes. This has been confirmed by Langmuir probe measurements on the LH launchers in the latest Tore-Supra experiments. Moreover, recent experiments in Jet indicate that the LH coupling degradation depends on the ICRF power and its launched k / spectrum. The 2D density distribution around the Tore-Supra ICRF antennas has been modelled with the CELLS-code, balancing parallel losses with diffusive transport and sheath induced ExB convection, obtained from RF field mapping using the ICANT-code. The calculations are in qualitative agreement with the experimental observations, i.e. density depletion is obtained, localised mainly in the antenna shadow, and dependent on ICRF power and antenna spectrum. (authors)
Density Convection near Radiating ICRF Antennas and its Effect on the Coupling of Lower Hybrid Waves
International Nuclear Information System (INIS)
Ekedahl, A.; Colas, L.; Beaumont, B.; Bibet, Ph.; Bremond, S.; Kazarian, F.; Mayoral, M.-L.; Mailloux, J.; Noterdaeme, J.-M.; Tuccillo, A.A.
2003-01-01
Combined operation of Lower Hybrid (LH) and Ion Cyclotron Resonance Frequency (ICRF) waves can result in a degradation of the LH wave coupling, as observed both in the Tore Supra and JET tokamaks. The reflection coefficient on the part of the LH launcher magnetically connected to the powered ICRF antenna increases, suggesting a local decrease in the electron density in the connecting flux tubes. This has been confirmed by Langmuir probe measurements on the LH launchers in the latest Tore Supra experiments. Moreover, recent experiments in JET indicate that the LH coupling degradation depends on the ICRF power and its launched k//-spectrum. The 2D density distribution around the Tore Supra ICRF antennas has been modelled with the CELLS-code, balancing parallel losses with diffusive transport and sheath induced ExB convection, obtained from RF field mapping using the ICANT-code. The calculations are in qualitative agreement with the experimental observations, i.e. density depletion is obtained, localised mainly in the antenna shadow, and dependent on ICRF power and antenna spectrum
Operation of ICRF antennas in a full tungsten environment in ASDEX Upgrade
Bobkov, Vl.; Braun, F.; Dux, R.; Giannone, L.; Herrmann, A.; Kallenbach, A.; Müller, H. W.; Neu, R.; Noterdaeme, J.-M.; Pütterich, Th.; Rohde, V.; ASDEX Upgrade Team
2009-06-01
In the 2007 and early part of 2008 experimental campaigns, ASDEX Upgrade operated with full tungsten (W) wall without boronization. Use of ICRF power results in a significant increase of W source. Low temperature conditions at the plasma facing components, achieved by a large clearance between the separatrix and the antenna (>6 cm) and by elevated gas puff rates (>5×1021 s) help to lower W sputtering yield during ICRF. Operation of neighboring ICRF antennas at the phase difference close to -90° can lead to a reduction in the W source. However, a reduction of parallel near-fields by antenna design is needed to further minimize the W source. A relation has been established between the HFSS code calculations predicting a dominant role of box currents in the formation of parallel antenna near-fields and the experiment. The shapes of the measured vertical profile of effective sputtering yields and the calculated sheath driving voltages show a qualitative agreement. This confirms that the existing tools are a good basis to design an improved antenna.
Operation of ICRF antennas in a full tungsten environment in ASDEX Upgrade
International Nuclear Information System (INIS)
Bobkov, Vl.; Braun, F.; Dux, R.; Giannone, L.; Herrmann, A.; Kallenbach, A.; Mueller, H.W.; Neu, R.; Noterdaeme, J.-M.; Puetterich, Th.; Rohde, V.
2009-01-01
In the 2007 and early part of 2008 experimental campaigns, ASDEX Upgrade operated with full tungsten (W) wall without boronization. Use of ICRF power results in a significant increase of W source. Low temperature conditions at the plasma facing components, achieved by a large clearance between the separatrix and the antenna (>6 cm) and by elevated gas puff rates (>5x10 21 s -1 ) help to lower W sputtering yield during ICRF. Operation of neighboring ICRF antennas at the phase difference close to -90 deg. can lead to a reduction in the W source. However, a reduction of parallel near-fields by antenna design is needed to further minimize the W source. A relation has been established between the HFSS code calculations predicting a dominant role of box currents in the formation of parallel antenna near-fields and the experiment. The shapes of the measured vertical profile of effective sputtering yields and the calculated sheath driving voltages show a qualitative agreement. This confirms that the existing tools are a good basis to design an improved antenna.
International Nuclear Information System (INIS)
Todd, A.M.M.; Phillips, M.W.
1986-04-01
A numerical code called GARFIELD has been developed to calculate the structure of ICRF electric fields in axisymmetric mirrors. It is being used to investigate ICRF wave structure of central cells of tandem mirror experiments. Fields are solved on a 2-D grid in the axial and radial directions. This permits us to study the effect that axial as well as radial variations of the magnetic field and density have on ICRF wave propagation and absorption. Much of this time frame was spent writing the code and refining the numerics. Initial calculations have been completed for the Phaedrus tandem mirror. These show that there is an evanescent fast wave structure in the radial direction, a standing wave formation in the axial direction, and a small amount of propagating ion cyclotron wave towards a shallow magnetic beach in the center of the mirror. In general, the fields peak on the outside which would show that the resulting pondermotive force would tend to stabilize the plasma
Resonance localization in tokamaks excited with ICRF waves
International Nuclear Information System (INIS)
Kerbel, G.D.; McCoy, M.G.
1985-01-01
Advanced wave models used to evaluate ICRH in tokamaks typically use warm plasma theory and allow inhomogeneity in one dimension. The majority of these calculations neglect the fact that gyrocenters experience the inhomogeneity via their motion parallel to the magnetic field. The non-local effects of rotational transform and toroidicity can play a significant role in both the propagation and the absorption physics. In strongly driven systems, wave damping can distort the particle distribution function supporting the wave and this produces changes in the absorption. The most common approach is to use Maxwellian absorption rates. We have developed a bounce-averaged Fokker-Planck quasilinear computational model which evolves the population of particles on more realistic orbits. Each wave-particle resonance has its own specific interaction amplitude within any given volume element; these data need only be generated once, and appropriately stored for efficient retrieval. The wave-particle resonant interaction then serves as a mechanism by which the diffusion of particle populations can proceed among neighboring orbits. The local specific spectral energy absorption rate is directly calculable once the orbit geometry and populations are determined. The code is constructed in such fashion as to accommodate wave propagation models which provide the wave spectral energy density on a poloidal cross-section. Information provided by the calculation includes the local absorption properties of the medium which can then be exploited to evolve the wave field
Study of ICRF wave propagation and plasma coupling efficiency in a linear magnetic mirror device
International Nuclear Information System (INIS)
Peng, S.Y.
1991-07-01
Ion Cyclotron Range of Frequency (ICRF) wave propagation in an inhomogeneous axial magnetic field in a cylindrical plasma-vacuum system has historically been inadequately modelled. Previous works either sacrifice the cylindrical geometry in favor of a simpler slab geometry, concentrate on the resonance region, use a single mode to represent the entire field structure, or examine only radial propagation. This thesis performs both analytical and computational studies to model the ICRF wave-plasma coupling and propagation problem. Experimental analysis is also conducted to compare experimental results with theoretical predictions. Both theoretical as well as experimental analysis are undertaken as part of the thesis. The theoretical studies simulate the propagation of ICRF waves in an axially inhomogeneous magnetic field and in cylindrical geometry. Two theoretical analysis are undertaken - an analytical study and a computational study. The analytical study treats the inhomogeneous magnetic field by transforming the (r,z) coordinate into another coordinate system (ρ,ξ) that allows the solution of the fields with much simpler boundaries. The plasma fields are then Fourier transformed into two coupled convolution-integral equations which are then differenced and solved for both the perpendicular mode number α as well as the complete EM fields. The computational study involves a multiple eigenmode computational analysis of the fields that exist within the plasma-vacuum system. The inhomogeneous axial field is treated by dividing the geometry into a series of transverse axial slices and using a constant dielectric tensor in each individual slice. The slices are then connected by longitudinal boundary conditions
Collision broadened resonance localization in tokamaks excited with ICRF waves
International Nuclear Information System (INIS)
Kerbel, G.D.; McCoy, M.G.
1985-08-01
Advanced wave models used to evaluate ICRH in tokamaks typically use warm plasma theory and allow inhomogeneity in one dimension. The authors have developed a bounce-averaged Fokker-Planck quasilinear computational model which evolves the population of particles on more realistic orbits. Each wave-particle resonance has its own specific interaction amplitude within any given volume element. These data need only be generated once, and appropriately stored for efficient retrieval. The wave-particle resonant interaction then serves as a mechanism by which the diffusion of particle populations can proceed among neighboring orbits. Collisions affect the absorption of rf energy by two quite distinct processes: In addition to the usual relaxation towards the Maxwellian distribution creating velocity gradients which drive quasilinear diffusion, collisions also affect the wave-particle resonance through the mechanism of gyro-phase diffusion. The local specific spectral energy absorption rate is directly calculable once the orbit geometry and populations are determined. The code is constructed in such fashion as to accommodate wave propagation models which provide the wave spectral energy density on a poloidal cross-section. Information provided by the calculation includes the local absorption properties of the medium which can then be exploited to evolve the wave field
Effects of Radial Electric Fields on ICRF Waves
International Nuclear Information System (INIS)
Phillips, C.K.; Hosea, J.C.; Ono, M.; Wilson, J.R.
2001-01-01
Equilibrium considerations infer that large localized radial electric fields are associated with internal transport barrier structures in tokamaks and other toroidal magnetic confinement configurations. In this paper, the effects of an equilibrium electric field on fast magnetosonic wave propagation are considered in the context of a cold plasma model
Antenna loading and electron heating experiments of ICRF wave in TNT-A tokamak
International Nuclear Information System (INIS)
Shinohara, Shunjiro; Asakura, Nobuyuki; Naito, Masahiro; Miyamoto, Kenro
1984-01-01
Antenna loading resistance and electron heating effects of ICRF wave were investigated in TNT-A tokamak. Lodaing resistance increased with the mean plasma density and decreased with the input power. The effect of the distance between the plasma and antenna surface on loading resistance was studied and had good agreements with the calculated results. The increase in the soft Xray emissivity was larger in the presence of ion-ion hybrid and/or ion cyclotron resonance layer in the plasma than that in the absence of them. With the absorbed power up to two times of the ohmic power, the central electron temperature increased by 20%, the soft Xray emissivity increased by 80% and the mean plasma density decreased by 10%, while the total radiation loss increased slightly (by 15%). (author)
Ion heating up to 1 MeV range with higher harmonic ICRF wave on JT-60U
International Nuclear Information System (INIS)
Nemoto, M.; Kusama, Y.; Hamamatsu, K.; Kimura, H.; Fujii, T.; Moriyama, S.; Saigusa, M.; Afanassiev, V.I.
1997-01-01
The properties of protons under accleration by an ion cyclotron range of frequency (ICRF) waves with the second to fourth hydrogen harmonics have been investigated in the JT-60U tokamak at the Japan Atomic Energy Research Institute (JAERI). Protons have been accelerated up to 1 MeV in the presence of an ICRF wave of fixed frequency, neutral beams (NB), and a fixed toroidal magnetic field which is scanned through several plasma discharges. The tail temperature of the protons, which is evaluated in the range 0.32-0.86 MeV, has been observed to increase in the second to third harmonics, however increase of the tail temperature in the third to fourth harmonics has not been observed clearly. Furthermore, the dependence of tail temperature on the harmonic number has been found to be in qualitative agreement with results from a simulation code analysis based upon the one-dimensional Fokker-Planck equation coupled with the kinetic wave equation. Experimental values for the stored energy of the accelerated ions have shown, however, that the response of stored energy to changes in absorbed ICRF power is much stronger than the response to changes in harmonic number. Also, the incremental energy confinement times for heating discharges matching the third and fourth harmonics (3 ω CH) and 4 ω CH) of hydrogen have been observed to be less than half that for those matching the second harmonic. It has been found that suppression of the absorbed ICRF power accompanied with the occurence of cavity resonance in the 3ω CH and 4ω CH heating discharges reduces the stored energy of the accelerated ions and the incremental energy confinement time. (Author)
International Nuclear Information System (INIS)
Tsujii, N.; Porkolab, M.; Bonoli, P. T.; Lin, Y.; Wright, J. C.; Wukitch, S. J.; Jaeger, E. F.; Green, D. L.; Harvey, R. W.
2012-01-01
Radio frequency waves in the ion cyclotron range of frequencies (ICRF) are widely used to heat tokamak plasmas. In ICRF heating schemes involving multiple ion species, the launched fast waves convert to ion cyclotron waves or ion Bernstein waves at the two-ion hybrid resonances. Mode converted waves are of interest as actuators to optimise plasma performance through current drive and flow drive. In order to describe these processes accurately in a realistic tokamak geometry, numerical simulations are essential, and it is important that these codes be validated against experiment. In this study, the mode converted waves were measured using a phase contrast imaging technique in D-H and D- 3 He plasmas. The measured mode converted wave intensity in the D- 3 He mode conversion regime was found to be a factor of ∼50 weaker than the full-wave predictions. The discrepancy was reduced in the hydrogen minority heating regime, where mode conversion is weaker.
International Nuclear Information System (INIS)
Gaudreau, M.P.J.
1981-09-01
Due to the versatility of the high power apparatus, the fast magnetosonic branch is used with ω 0 = 1,2,3,4 ω/sub ci/, unlike most other ICRF experiments. Unusually high magnetic field (B 0 = 40 to 80 kG), plasma density (n/sub e/ = 10 13 - 5 x 10 14 /cm 3 ), generator frequency (f 0 = 90 to 200 MHz) and transmitter power, with shielded and unshielded antennas, are the key parameters of the experiment. This wide parameter range allows a direct comparison between fundamental and second harmonic regimes, and shielded and unshielded antennas, our prime goals. The real and imaginary parts of the parallel and perpendicular wave numbers are measured with extensive magnetic probe diagnostics for a spectrum of plasma parameters and compared with theory. Qualitative and quantitative evaluations of the wave structure and scaling laws are derived analytically in simple geometries and computed numerically for realistic plasma parameters and profiles. General figures of merit, such as radiation resistance and quality factor, are also derived and compared with the experiment. Secondary effects of the high power wave launching, such as changes in plasma current, density, Z/sub eff/, energetic neutral flux, soft x-rays, neutron flux, and impurities are also discussed. Most important, a general synthesis of the many engineering, physics, and experimental problems and conclusions of the Alcator A ICRF program are inspected in detail. Finally, the derived and experimentally determined scaling laws and engineering constraints are used to estimate the ICRF requrements, advantages, and potential pitfalls of the next generations of experiments on the Alcator tokamaks
Slow Wave Propagation and Sheath Interaction for ICRF Waves in the Tokamak SOL
International Nuclear Information System (INIS)
Myra, J. R.; D'Ippolito, D. A.
2009-01-01
In previous work we studied the propagation of slow-wave resonance cones launched parasitically by a fast-wave antenna into a tenuous magnetized plasma. Here we extend the previous calculation to ''dense'' scrape-off-layer (SOL) plasmas where the usual slow wave is evanescent. Using the sheath boundary condition, it is shown that for sufficiently close limiters, the slow wave couples to a sheath plasma wave and is no longer evanescent, but radially propagating. A self-consistent calculation of the rf-sheath width yields the resulting sheath voltage in terms of the amplitude of the launched SW, plasma parameters and connection length.
International Nuclear Information System (INIS)
Nelson, B.A.
1987-01-01
Ion-confining potentials in the Phaedrus tandem mirror are shown to be enhanced over Boltzmann-relations predicted values by radio-frequency (rf) waves in the ion cyclotron range of frequencies (ICRF). The ICRF enhanced potential is larger in the end cell with a lower passing density. Peak potential values decrease with increasing ion endloss current (or central cell density) for a constant rf capacitor bank voltage, and increase with increasing rf-capacitor bank voltage, for a constant ion endloss value (or central cell density). In fully axisymmetric operation, a potential peak is produced in an end cell by the central-cell rf, (with-out end-cell rf) and is found only in the end cell nearer the central-cell antenna. ICRF enhanced potentials are explained as an equilibrium between the electron-collisional filling-in rate and the electron pumping out rate provided by axial time-varying electric fields. Thermal barrier-like potential structures were found in the transition regions between the central cell and end cells, in the fully axisymmetric Phaedrus. Central-cell ICRF trapping effects combined with end-cell μΔ B forces create and pump the barrier potential wells
ICRF Wave Propagation and Absorption in Plasmas with Non-thermal Populations
International Nuclear Information System (INIS)
Dumont, R.J.; Phillips, C.K.; Smithe, D.N.
2002-01-01
Some results obtained with the one dimensional, all orders, full wave code METS, which has been successfully employed in the past to describe a number of experiments, are reported. By using massively parallel computers, this code has been extended to handle non-thermal populations. Various physical situations, in which non-Maxwellian species are expected to be encountered, are studied, such as simultaneous neutral beam injection and high harmonic fast wave electron heating or ion cyclotron resonance heating in the presence of fusion products
Fast-wave ICRF minority-regime heating experiments on the Tore Supra tokamak
Energy Technology Data Exchange (ETDEWEB)
Agarici, G; Beaumont, B; Becoulet, A; Kuus, H; Saoutic, B; Martin, G [Association Euratom-CEA, Centre d` Etudes Nucleaires de Cadarache, 13 - Saint-Paul-lez-Durance (FR). Dept. de Recherches sur la Fusion Controlee; Shepard, T D; Haste, G R; Baity, F W [Oak Ridge National Lab., TN (US); Evans, T E [General Atomics, San Diego, CA (US)
1992-12-31
Up to 4 MW of rf power at 57 MHz has been coupled to Ohmic target plasmas during the first ICRF heating experiments on Tore Supra. A total of 12 MW of rf power will ultimately be available from six tetrode amplifiers and will be coupled to the plasmas using three ORNL/CEA-designed resonant double-loop antennas. During these first experiments, two antennas were used, with one or two energized at a time. The antenna loading with plasma was observed to be well over an order of magnitude greater than that without plasma. In addition, one kilo-electron-volt of electron heating, significant minority nonthermal ions, and significant increases in diamagnetic stored energy were observed. A comparison of in-phase and out-of-phase antenna operation showed the same increase in stored energy, less radiated power, and a larger drop in loop voltage for out-of-phase operation. Confinement scaling agrees with the ITER scaling law.
Three-dimensional calculation analysis of ICRF heating in LHD
International Nuclear Information System (INIS)
Seki, Tetsuo; Kumazawa, Ryuhei; Mutoh, Takashi
2004-01-01
Ion cyclotron range of frequencies (ICRF) heating is one of the heating methods for the fusion plasma experiments and also effective for the helical plasmas. For the purpose of analysis of the ICRF heating in the helical plasmas, the three-dimensional full-wave code has been developed. The feature of the helical system compared with the tokamak device is the strong coupling of the toroidal harmonic modes. They cannot be treated independently. Dependence of the power absorption on the position of the ion cyclotron resonance layer is calculated including all toroidal modes. Strong power absorption was obtained when the position of the resonance layer is slightly different from the experimental results. Difference of the position of the resonance layer in different toroidal angle is thought to be important to achieve the good heating efficiency in the ICRF heating for the helical plasmas. (author)
Localized bulk electron heating with ICRF mode conversion in the JET tokamak
DEFF Research Database (Denmark)
Mantsinen, M.J.; Mayoral, M.-L.; Eester, D. Van
2004-01-01
of the He-3 ion cyclotron resonance layer in D and He-4 plasmas and subsequently damped on the bulk electrons. The resulting electron power deposition, measured using ICRF power modulation, is narrow with a typical full-width at half-maximum of approximate to30 cm (i.e. about 30% of the minor radius......) and the total deposited power to electrons comprises at least up to 80% of the applied ICRF power. The ICRF mode conversion power deposition has been kept constant using He-3 bleed throughout the ICRF phase with a typical duration of 4-6 s, i.e. 15-40 energy confinement times. Using waves propagating...
International Nuclear Information System (INIS)
Valeo, E.J.; Phillips, C.K.; Bonoli, P.T.; Wright, J.C.; Brambilla, M.
2007-01-01
The generation of energetic tails in the electron distribution function is intrinsic to lower-hybrid (LH) heating and current drive in weakly collisional magnetically confined plasma. The effects of these deformations on the RF deposition profile have previously been examined within the ray approximation. Recently, the calculation of full-wave propagation of LH waves in a thermal plasma has been accomplished using an adaptation of the TORIC code. Here, initial results are presented from TORIC simulations of LH propagation in a toroidal plasma with non-thermal electrons. The required efficient computation of the hot plasma dielectric tensor is accomplished using a technique previously demonstrated in full-wave simulations of ICRF propagation in plasma with non-thermal ions
The numerical solution of ICRF fields in axisymmetric mirrors
International Nuclear Information System (INIS)
Phillips, M.W.; Todd, A.M.M.
1986-01-01
The numerics of a numerical code called GARFIELD (Grumman Aerospace RF fIELD code) designed to calculate the three-dimensional structure of ICRF fields in axisymmetric mirrors is presented. The code solves the electromagnetic wave equation for the electric field using a cold plasma dispersion relation with a small collision term to simulate absorption. The full wave solution including E.B is computed. The fields are Fourier analyzed in the poloidal direction and solved on a grid in the axial and radial directions. A two-dimensional equilibrium can be used as the source of equilibrium data. This allows us to extend previous studies of ICRF wave propagation and absorption in mirrors to include the effect of axial variation of the magnetic field and density. (orig.)
Effects induced by ICRF waves on various confinement schemes in Tore Supra
International Nuclear Information System (INIS)
Saoutic, B.
1995-01-01
The 1993-94 experimental campaign has seen a significant increase of the application of waves in the ion cyclotron range of frequency on Tore Supra. Ion cyclotron resonant heating has been applied to plasmas with strongly radiating layers, pellet-enhanced performance and lower hybrid enhanced performance. Initial experiments on direct coupling of the fast magnetosonic wave to the electrons have demonstrated coupling up to 5 MW to the plasma and have demonstrated an efficient electron heating in these discharges. A significant bootstrap current fraction is observed. This heating scheme leads to a stationary improvement in energy confinement, with implications for the Rebut-Lallia-Watkins local transport model. Finally, preliminary experiments on antenna phasing have shown clear evidence of fast wave current drive. (author) 25 refs.; 9 figs
Heat loads on JET plasma facing components from ICRF and LH wave absorption in the SOL
Czech Academy of Sciences Publication Activity Database
Jacquet, P.; Colas, L.; Mayoral, M.-L.; Arnoux, G.; Bobkov, V.; Brix, M.; Coad, P.; Czarnecka, A.; Dodt, D.; Durodie, F.; Ekedahl, A.; Frigione, D.; Fursdon, M.; Gauthier, E.; Goniche, M.; Graham, M.; Joffrin, E.; Korotkov, A.; Lerche, E.; Mailloux, J.; Monakhov, I.; Noble, C.; Ongena, J.; Petržílka, Václav; Portafaix, C.; Rimini, F.; Sirinelli, A.; Riccardo, V.; Vizvary, Z.; Widdowson, A.; Zastrow, K.-D.
2011-01-01
Roč. 51, č. 10 (2011), s. 103018-103018 ISSN 0029-5515 R&D Projects: GA ČR GA202/07/0044 Institutional research plan: CEZ:AV0Z20430508 Keywords : LH wave * plasma Subject RIV: BL - Plasma and Gas Discharge Physics Impact factor: 4.090, year: 2011 http://iopscience.iop.org/0029-5515/51/10/103018/pdf/0029-5515_51_10_103018.pdf
FISIC - a full-wave code to model ion cyclotron resonance heating of tokamak plasmas
International Nuclear Information System (INIS)
Kruecken, T.
1988-08-01
We present a user manual for the FISIC code which solves the integrodifferential wave equation in the finite Larmor radius approximation in fully toroidal geometry to simulate ICRF heating experiments. The code models the electromagnetic wave field as well as antenna coupling and power deposition profiles in axisymmetric plasmas. (orig.)
ICRF heating on helical devices
International Nuclear Information System (INIS)
Rasmussen, D.A.; Lyon, J.F.; Hoffman, D.J.; Murakami, M.; England, A.C.; Wilgen, J.B.; Jaeger, E.F.; Wang, C.; Batchelor, D.B.
1995-01-01
Ion cyclotron range of frequency (ICRF) heating is currently in use on CHS and W7-AS and is a major element of the heating planned for steady state helical devices. In helical devices, the lack of a toroidal current eliminates both disruptions and the need for ICRF current drive, simplifying the design of antenna structures as compared to tokamak applications. However the survivability of plasma facing components and steady state cooling issues are directly applicable to tokamak devices. Results from LHD steady state experiments should be available on a time scale to strongly influence the next generation of steady state tokamak experiments. The helical plasma geometry provides challenges not faced with tokamak ICRF heating, including the potential for enhanced fast ion losses, impurity accumulation, limited access for antenna structures, and open magnetic field lines in the plasma edge. The present results and near term plans provide the basis for steady state ICRF heating of larger helical devices. An approach which includes direct electron, mode conversion, ion minority and ion Bernstein wave heating addresses these issues
ICRF heating on helical devices
International Nuclear Information System (INIS)
Rasmussen, D.A.; Lyon, J.F.; Hoffman, D.J.
1995-01-01
Ion cyclotron range of frequency (ICRF) heating is currently in use on CHS and W7AS and is a major element of the heating planned for steady state helical devices. In helical devices, the lack of a toroidal current eliminates both disruptions and the need for ICRF current drive, simplifying the design of antenna structures as compared to tokamak applications. However the survivability of plasma facing components and steady state cooling issues are directly applicable to tokamak devices. Results from LHD steady state experiments should be available on a time scale to strongly influence the next generation of steady state tokamak experiments. The helical plasma geometry provides challenges not faced with tokamak ICRF heating, including the potential for enhanced fast ion losses, impurity accumulation, limited access for antenna structures, and open magnetic field lines in the plasma edge. The present results and near term plans provide the basis for steady state ICRF heating of larger helical devices. An approach which includes direct electron, mode conversion, ion minority and ion Bernstein wave heating addresses these issues
International Nuclear Information System (INIS)
1991-01-01
This report describes the technical progress for the DOE sponsored grant, ''ICRF Edge Modeling.'' An emphasis is placed on the progress since the Technical Progress Report (January 10, 1990) was submitted to the Department of Energy. The design of ICRF antennas for C-Mod and TFTR was investigated during this period. In addition, quasilinear models for electron heating were refined and applied to the design of ICRF antennas. The relevant professional activities sponsored by this grant are given. 4 refs., 11 figs
Source Estimation by Full Wave Form Inversion
Energy Technology Data Exchange (ETDEWEB)
Sjögreen, Björn [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States). Center for Applied Scientific Computing; Petersson, N. Anders [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States). Center for Applied Scientific Computing
2013-08-07
Given time-dependent ground motion recordings at a number of receiver stations, we solve the inverse problem for estimating the parameters of the seismic source. The source is modeled as a point moment tensor source, characterized by its location, moment tensor components, the start time, and frequency parameter (rise time) of its source time function. In total, there are 11 unknown parameters. We use a non-linear conjugate gradient algorithm to minimize the full waveform misfit between observed and computed ground motions at the receiver stations. An important underlying assumption of the minimization problem is that the wave propagation is accurately described by the elastic wave equation in a heterogeneous isotropic material. We use a fourth order accurate finite difference method, developed in [12], to evolve the waves forwards in time. The adjoint wave equation corresponding to the discretized elastic wave equation is used to compute the gradient of the misfit, which is needed by the non-linear conjugated minimization algorithm. A new source point moment source discretization is derived that guarantees that the Hessian of the misfit is a continuous function of the source location. An efficient approach for calculating the Hessian is also presented. We show how the Hessian can be used to scale the problem to improve the convergence of the non-linear conjugated gradient algorithm. Numerical experiments are presented for estimating the source parameters from synthetic data in a layer over half-space problem (LOH.1), illustrating rapid convergence of the proposed approach.
Simulation study of energetic ion distribution during combined NBI and ICRF heating in LHD
International Nuclear Information System (INIS)
Murakami, S.; Fukuyama, A.; Kasilov, V.
2006-01-01
In the LHD, significant performances of ICRF heating (fundamental, minority heating regime) have been demonstrated and up to 500keV of energetic tail ions have been observed by fast neutral particle analysis (NPA). These measured results indicate a good property of energetic ion confinement in helical systems. From the 9th campaign of LHD experiment (FY2005) a new perpendicular NBI heating system (P<3MW) has been installed and an effective heating of perpendicularly injected beam ions by the higher harmonics ICRF heating is expected. ICRF heating generates highly energetic tail ions, which drift around the torus for a long time (typically on a collisional time scale). Thus, the behavior of these energetic ions is strongly affected by the characteristics of the drift motions, which depend on the magnetic field configuration. In particular, in a three-dimensional (3D) magnetic configuration, complicated drift motions of trapped particles would play an important role in the confinement of the energetic ions and the ICRF heating process. Therefore a global simulation of ICRF heating is necessary for the accurate modeling of the plasma heating process in a 3D magnetic configuration. In this paper we study the energetic ion distribution during combined NBI and 2nd harmonics ICRF heating in LHD using two global simulation codes: a full wave field solver TASK/WK and a drift kinetic equation solver GNET. GNET solves a linearized drift kinetic equation for energetic ions including complicated behavior of trapped particles in 5-D phase space. TASK/WM solves Maxwell's equation for RF wave electric field with complex frequency as a boundary value problem in the 3D magnetic configuration. (author)
Full wave simulations of lower hybrid wave propagation in tokamaks
International Nuclear Information System (INIS)
Wright, J. C.; Bonoli, P. T.; Phillips, C. K.; Valeo, E.; Harvey, R. W.
2009-01-01
Lower hybrid (LH) waves have the attractive property of damping strongly via electron Landau resonance on relatively fast tail electrons at (2.5-3)xv te , where v te ≡ (2T e /m e ) 1/2 is the electron thermal speed. Consequently these waves are well-suited to driving current in the plasma periphery where the electron temperature is lower, making LH current drive (LHCD) a promising technique for off-axis (r/a≥0.60) current profile control in reactor grade plasmas. Established techniques for computing wave propagation and absorption use WKB expansions with non-Maxwellian self-consistent distributions.In typical plasma conditions with electron densities of several 10 19 m -3 and toroidal magnetic fields strengths of 4 Telsa, the perpendicular wavelength is of the order of 1 mm and the parallel wavelength is of the order of 1 cm. Even in a relatively small device such as Alcator C-Mod with a minor radius of 22 cm, the number of wavelengths that must be resolved requires large amounts of computational resources for the full wave treatment. These requirements are met with a massively parallel version of the TORIC full wave code that has been adapted specifically for the simulation of LH waves [J. C. Wright, et al., Commun. Comput. Phys., 4, 545 (2008), J. C. Wright, et al., Phys. Plasmas 16 July (2009)]. This model accurately represents the effects of focusing and diffraction that occur in LH propagation. It is also coupled with a Fokker-Planck solver, CQL3D, to provide self-consistent distribution functions for the plasma dielectric as well as a synthetic hard X-ray (HXR) diagnostic for direct comparisons with experimental measurements of LH waves.The wave solutions from the TORIC-LH zero FLR model will be compared to the results from ray tracing from the GENRAY/CQL3D code via the synthetic HXR diagnostic and power deposition.
ICRF/edge physics research on TEXTOR
International Nuclear Information System (INIS)
Oost, G. van; Nieuwenhove, R. van; Koch, R.; Messiaen, A.M.; Vandenplas, P.E.; Weynants, R.R.; Dippel, K.H.; Finken, K.H.; Lie, Y.T.; Pospieszczyk, A.; Samm, U.; Schweer, B.; Conn, R.W.; Corbett, W.J.; Goebel, D.M.; Moyer, R.A.; California Univ., Los Angeles
1990-01-01
Extensive investigations of ICRF-induced effects on the edge plasma and on plasma-wall interaction were conducted on TEXTOR under different wall- and limiter as well as plasma- and heating conditions. Several strong effects of ICRF on the edge parameters were observed on TEXTOR, such as density rise, instantaneous electron heating, modification of SOL profiles, influx of ligth and/or heavy impurities, increased heat flux to the limiters, and production of energetic ions in the SOL. The fast response time of some of the changes and the observation of a maximum in the SOL profile of electron temperature, heat flux and metal sputtering clearly demonstrated that RF power is directly absorbed in the SOL. Estimates of this power amount to several percent of the total RF power launched into the plasma. Plasma-wall interaction during ICRF was substantially reduced by an appropriate choice of the wall conditioning procedures (wall carbonization with liner at 400degC or, above all, boronization). As a result record low values of the radiated power fraction were achieved during ICRF and long pulse, high power, low impurity operation was possible. Further improvement was obtained by ICRF antenna phasing. When ICRF power is coupled to the plasma, several effects on the core and edge plasma influence the operation of the toroidal pump limiter ALT-II. Experimental and theoretical studies were performed to elucidate the mechanisms responsible for the ICRF-induced effects, including the propagation of plasma waves in the edge plasma and nonlinear phenomena such as parametric decay, important changes in the DC current between the antenna structure and the liner due to the sheath effect at the antennas, and the generation of waves at harmonics of the RF generator frequency. Radial profiles of the DC radial and poloidal electric fields as well as a localized RF electric field structure were measured in the SOL using a fast scanning probe. (orig.)
International Nuclear Information System (INIS)
Sharer, J.E.; Bettenhausen, M.; Lam, N.; Sund, R.
1994-08-01
The research performed under this grant during the past year has concentrated on coupling, heating, and current drive issues for TFTR. The authors have developed a code and submitted for publication a open-quotes 3-Dclose quotes coupling analysis of the TFIR ICRF cavity-backed coil antennas to plasma edge profiles including the Faraday shield blade angle and fast wave coupling for heating and current drive. They have also carried out TFTR ICRF full-wave field solutions and heating analyses for the second harmonic tritium supershot, and the effects of fusion alpha particle and tritium ion tail populations on the ICRF absorption. They have also published a paper on the effects of alpha particle absorption on fundamental deuterium ion cyclotron absorption incorporating self-consistent deuterium tails and fusion reactivity. Research progress, publications, and conference presentations are summarized in this report
Two frequency ICRF operation on TFTR
International Nuclear Information System (INIS)
Rogers, J.H.; Majeski, R.; Wilson, J.R.; Hosea, J.C.; Schilling, G.; Stevens, J.; Phillips, C.K.
1993-01-01
Modifications have been made recently to allow two of the ICRF antennas (bays L and M) on TFTR to operate at either of two frequencies, 43 MHz or 64 MHz. This was accomplished by lengthening the resonant loops (2Λ at 43 MHz, 3Λ at 64 MHz) and replacing the conventional quarter wave impedance transformers with a tapered impedance design. The other two antennas (bays K and N) will operate at a fixed frequency, 43 MHz. The two frequency operation will allow a combination of 3 He-minority and H-minority heating at near full field on TFTR. The higher frequency, 64 MHz, may also be useful in direct electron heating and current drive experiments at lower toroidal fields. Models of the antenna, resonant loops and impedance matching system are presented
Electromagnetic simulations of JET ICRF ITER-like antenna with TOPICA and SSWICH asymptotic codes
Directory of Open Access Journals (Sweden)
Křivská Alena
2017-01-01
Full Text Available Multi-megawatt Ion Cyclotron Range of Frequencies (ICRF heating is routinely used in the JET tokamak. To increase the ICRF heating power available from the A2 antennas, the ICRF ITER-Like Antenna (ILA was reinstalled for the 2015 JET ITER-like wall experimental campaign. The application of high levels of ICRF power typically results in increased plasma wall interaction which leads to the observation of enhanced influx of metallic impurities in the plasma edge. It is assumed that the impurity production is mainly driven by the parallel component of the Radio-Frequency (RF antenna electric near-field, E// (parallel to the confinement magnetic field of the tokamak, that is rectified in a thin boundary layer (RF sheath. Torino Polytechnic Ion Cyclotron Antenna (TOPICA code was used to compute E// field maps in front of the ILA and between its poloidal limiters in the presence of plasma using measured density profiles and various antenna feedings. E// field maps calculated between the poloidal limiters were used to estimate the poloidal distribution of RF-sheath Direct Current (DC potential in this private region of the ILA and make relative comparison of various antenna electrical settings. For this purpose we used the asymptotic version of the Self-consistent Sheaths and Waves for Ion Cyclotron Heating Slow-Wave (SSWICH-SW code. These estimations can help to study the formation of RF sheaths around the antenna and even at distant locations (∼3m away.
Energy Technology Data Exchange (ETDEWEB)
Lehrman, I.S. (Grumman Corp. Research Center, Princeton, NJ (USA)); Colestock, P.L. (Princeton Univ., NJ (USA). Plasma Physics Lab.)
1990-04-01
Theoretical models have been developed, and are currently being refined, to explain the edge plasma-antenna interaction that occurs during ICRF heating. The periodic structure of a Faraday shielded antenna is found to result in strong ponderomotive force in the vicinity of the antenna. A fluid model, which incorporates the ponderomotive force, shows an increase in transport to the Faraday shield. A kinetic model shows that the strong antenna near fields act to increase the energy of deuterons which strike the shield, thereby increasing the sputtering of shield material. Estimates of edge impurity harmonic heating show no significant heating for either in or out-of-phase antenna operation. Additionally, a particle model for electrons near the shield shows that heating results from the parallel electric field associated with the fast wave. A quasilinear model for edge electron heating is presented and compared to the particle calculations. The models' predictions are shown to be consistent with measurements of enhanced transport. (orig.).
Energy Technology Data Exchange (ETDEWEB)
Tsuchiya, T [Dia Consultants Company, Tokyo (Japan)
1996-10-01
Nonlinear full-wave tomography (FWT) is under investigation to improve the estimation accuracy of Vp/Vs distributions. Full-wave tomography is one of the underground structure exploration methods mainly using Tarantola`s nonlinear local optimization method (LOM). Numerical experiment for FWT was carried out assuming relatively weak nonlinear underground structure. In the case of inversion by local optimization method, adequate preconditioning is important. Utilization of geological information is also effective in estimating low-frequency components of a model. As far as data are obtained under proper observation arrangement, even in actual field, precise estimation of Vp/Vs distributions is possible by FWT using explosion in a hole as wave source. In full-wave tomography, selection of observation arrangement is essential for both Vp and Vs. However, the proper arrangement is different between Vp and Vs. Approach to different analyses for Vp and Vs is also necessary by using only proper data for Vp and Vs among obtained data sets. 4 figs.
ICRF heating on the burning plasma experiment (BPX)
International Nuclear Information System (INIS)
Batchelor, D.B.; Carter, M.D.; Goulding, R.H.; Hoffman, D.J.; Jaeger, E.F.; Ryan, P.M.; Swain, D.W.; Tolliver, J.S.; Yugo, J.J.; Goldston, R.J.; Hosea, J.C.; Kaye, S.M.; Phillips, C.K.; Wilson, J.R.; Mau, T.K.
1991-01-01
RF power in the ion cyclotron range of frequencies (ICRF) has been chosen as the primary heating technique for BPX. This decision is based on the wide success of ICRF heating in existing experiments (JET, TFTR, JT-60), the capability of ion cyclotron waves to penetrate the high-density plasmas of BPX, the ability to concentrate ICRF power deposition near the plasma center, and the ready availability of high-power sources at the appropriate frequency. The primary task of the ICRF system is to heat the plasma to ignition. However, other important roles are envisaged; these include the stabilization of sawteeth, preheating of the plasma during current ramp-up, and possible control of the plasma current profile by means of fast-wave current drive. We give a brief overview of the RF system, describe the operating scenarios planned for BPX, and discuss some of the antenna design issues for BPX. 4 refs., 3 figs
Upgrade of ICRF heating system on EAST
International Nuclear Information System (INIS)
Chen Gen; Zhao Yanpin; Mao Yuzhou
2013-01-01
ICRF (Ion Cyclotron Range of Frequency) heating is an essential heating and current drive tool on EAST (Experimental Advanced Superconducting Tokamak). The high-power steady-state transmitters were designed as a part of research and development of ICRF heating system which aimed at output power of 1.5 MW for 1000 s in a frequency range of 25 to 70 MHz. There are 3 stage power amplifiers for each transmitter. Tube TH525A and TH535 were chosen for drive power amplifier (DPA) and final power amplifier (FPA), respectively. The power supply system of DPA and FPA were upgraded by using reliable PSM high voltage sources, whose response time is less than 5 μs. The ICRF system, which consists of 8 transmitters, will give out more than 10 MW total output power in the future. Four of them have been already fabricated, and another four are under construction. Three liquid stub tuners are used for impedance matching between antennas and transmitters, which can be only tuned shot to shot. There are two fast wave heating antennas which are assembled at I port and B port on EAST. Several projects are in progress including fast response impedance matching, distributed data acquisition and control system and so on for EAST ICRF heating system. (author)
International Nuclear Information System (INIS)
Choi, M.; Chan, V. S.; Chu, M. S.; Lao, L. L.; Pinsker, R. I.; Turnbull, A. D.; Jeon, Y. M.; Li, G.; Ren, Q.
2007-01-01
We evaluate the accuracy of the Porcelli sawtooth model using more realistic numerical models from the ORBIT-RF and GATO codes in DIII-D fast wave heating experiments. Simulation results confirm that the fast wave-induced energetic trapped particles may stabilize the sawtooth instability. The crucial kinetic stabilizing contribution strongly depends on both the experimentally reconstructed magnetic shear at the q = 1 surface and the calculated poloidal beta of energetic trapped particles inside the q = 1 surface
Full-wave current conveyor precision rectifier
Directory of Open Access Journals (Sweden)
Đukić Slobodan R.
2008-01-01
Full Text Available A circuit that provides precision rectification of small signal with low temperature sensitivity for frequencies up to 100 kHz without waveform distortion is presented. It utilizes an improved second type current conveyor based on current-steering output stage and biased silicon diodes. The use of a DC current source to bias the rectifying diodes provides higher temperature stability and lower DC offset level at the output. Proposed design of the precision rectifier ensures good current transfer linearity in the range that satisfy class A of the amplifier and good voltage transfer characteristic for low level signals. Distortion during the zero crossing of the input signal is practically eliminated. Design of the proposed rectifier is realized with standard components.
Mechanical design of the second ICRF antenna for EAST
Energy Technology Data Exchange (ETDEWEB)
Yang, X.Q., E-mail: yangqx@ipp.ac.cn [Institute of Plasma Physics, Chinese Academy of Sciences, Hefei 230031 (China); Song, Y.T.; Wu, S.T.; Zhao, Y.P.; Zhang, J.X.; Wang, Z.W. [Institute of Plasma Physics, Chinese Academy of Sciences, Hefei 230031 (China)
2012-08-15
Highlights: Black-Right-Pointing-Pointer The second ICRF antenna of EAST is capable of coupling higher power than the former ICRF antenna due to it has been designed with four current straps. Black-Right-Pointing-Pointer Many cooling channels have been designed for the key components of faraday shied, current strap, baffles and transmission lines, which can remove the dissipated RF loss power and incoming heat loads on them and make ICRF antenna being capable of coupling higher power in constant wave operation. Black-Right-Pointing-Pointer Extra structure via cantilever support beam has been designed to support the forepart of the ICRF antenna. Black-Right-Pointing-Pointer Numerical analysis by applying the thermo-mechanical coupling method have been applied to analyze for the key components of ICRF antenna. - Abstract: In order to satisfy the requirements of heating plasma on EAST project, 3 MW ion cyclotron range of frequency (ICRF) heating system will be available at the second stage. Based on this requirement, the second ICRF antenna, has been designed for EAST. The antenna which is planned to operate with a frequency ranging from 30 MHz to 110 MHz, comprises four poloidal current straps. The antenna has many cooling channels inside the current straps, faraday shield and baffle to remove the dissipated RF loss power and incoming plasma heat loads. The antenna is supported via a cantilever support box to the external support structure. Its assembly is plugged in the port and fixed on the support box. External slideway and bellows allow the antenna to be able to move in the radial direction. The key components of the second ICRF antenna has been designed together with structural and thermal analysis presented.
ICRF induced edge plasma convection in ASDEX upgrade
Energy Technology Data Exchange (ETDEWEB)
Zhang, Wei [Max Planck Institute for Plasma Physics, Garching/Greifswald (Germany); University of Ghent, Ghent (Belgium); Institute of Plasma Physics, Chinese Academy of Sciences, Hefei (China); Feng, Yuehe; Lunt, Tilmann; Jacquot, Jonathan; Coster, David; Bilato, Roberto; Bobkov, Volodymyr; Ochoukov, Roman [Max Planck Institute for Plasma Physics, Garching/Greifswald (Germany); Noterdaeme, Jean-Marie [Max Planck Institute for Plasma Physics, Garching/Greifswald (Germany); University of Ghent, Ghent (Belgium); Colas, Laurent [CEA, IRFM, Saint-Paul-Lez-Durance (France); Collaboration: ASDEX Upgrade Team
2016-07-01
Ion Cyclotron Range of Frequency (ICRF) heating is one of the main auxiliary plasma heating methods in tokamaks. It relies on the fast wave to heat the plasma. However the slow wave can also be generated parasitically. The parallel electric field of the slow wave can induce large biased plasma potential through sheath rectification. The rapid variation of this rectified potential across the magnetic field can cause significant E x B convection in the Scrape-Off Layer (SOL). The ICRF induced convection can affect the SOL density, influence the ICRF power coupling and enhance the strength of plasma-wall interactions. To explore these physics, we not only show the experimental evidences in ASDEX Upgrade, but also present the associated simulation results with the 3D edge plasma fluid code EMC3-Eirene. Further simulations via combination of EMC3-Eirene and a sheath code SSWICH in an iterative and quasi self-consistent way can give good predictions for future experiments.
Source inversion in the full-wave tomography; Full wave tomography ni okeru source inversion
Energy Technology Data Exchange (ETDEWEB)
Tsuchiya, T [DIA Consultants Co. Ltd., Tokyo (Japan)
1997-10-22
In order to consider effects of characteristics of a vibration source in the full-wave tomography (FWT), a study has been performed on a method to invert vibration source parameters together with V(p)/V(s) distribution. The study has expanded an analysis method which uses as the basic the gradient method invented by Tarantola and the partial space method invented by Sambridge, and conducted numerical experiments. The experiment No. 1 has performed inversion of only the vibration source parameters, and the experiment No. 2 has executed simultaneous inversion of the V(p)/V(s) distribution and the vibration source parameters. The result of the discussions revealed that and effective analytical procedure would be as follows: in order to predict maximum stress, the average vibration source parameters and the property parameters are first inverted simultaneously; in order to estimate each vibration source parameter at a high accuracy, the property parameters are fixed, and each vibration source parameter is inverted individually; and the derived vibration source parameters are fixed, and the property parameters are again inverted from the initial values. 5 figs., 2 tabs.
The essential theory of fast wave current drive with full wave method
International Nuclear Information System (INIS)
Liu Yan; Gong Xueyu; Yang Lei; Yin Chenyan; Yin Lan
2007-01-01
The full wave numerical method is developed for analyzing fast wave current drive in the range of ion cyclotron waves in tokamak plasmas, taking into account finite larmor radius effects and parallel dispersion. the physical model, the dispersion relation on the assumption of Finite Larmor Radius (FLR) effects and the form of full wave be used for computer simulation are developed. All of the work will contribute to further study of fast wave current drive. (authors)
2D full wave simulation on electromagnetic wave propagation in toroidal plasma
International Nuclear Information System (INIS)
Hojo, Hitoshi; Uruta, Go; Nakayama, Kazunori; Mase, Atsushi
2002-01-01
Global full-wave simulation on electromagnetic wave propagation in toroidal plasma with an external magnetic field imaging a tokamak configuration is performed in two dimensions. The temporal behavior of an electromagnetic wave launched into plasma from a wave-guiding region is obtained. (author)
Design and Control of Full Scale Wave Energy Simulator System
DEFF Research Database (Denmark)
Pedersen, Henrik C.; Hansen, Anders Hedegaard; Hansen, Rico Hjerm
2012-01-01
For wave energy to become feasible it is a requirement that the efficiency and reliability of the power take-off (PTO) systems are significantly improved. The cost of installing and testing PTO-systems at sea are however very high, and the focus of the current paper is therefore on the design...... of a full scale wave simulator for testing PTO-systems for point absorbers. The main challenge is here to design a system, which mimics the behavior of a wave when interacting with a given PTO-system. The paper includes a description of the developed system, located at Aalborg University......, and the considerations behind the design. Based on the description a model of the system is presented, which, along with a description of the wave theory applied, makes the foundation for the control strategy. The objective of the control strategy is to emulate not only the wave behavior, but also the dynamic wave...
Detection of sinkholes or anomalies using full seismic wave fields.
2013-04-01
This research presents an application of two-dimensional (2-D) time-domain waveform tomography for detection of embedded sinkholes and anomalies. The measured seismic surface wave fields were inverted using a full waveform inversion (FWI) technique, ...
Development and test of decoupler for ICRF antenna in EAST
Energy Technology Data Exchange (ETDEWEB)
Chen, Gen, E-mail: chengen@ipp.ac.cn; Mao, Yuzhou; Zhao, Yanping; Yuan, Shuai; Zhang, Xinjun; Qing, Chengming
2016-06-15
Highlights: • The mechanism of decoupler for ICRF antenna is proposed. • Three candidate assembly positions for the decouper can be used. • The performance relies on the ohmic dissipation and the assembly position of decoupler. - Abstract: Ion Cyclotron Range of Frequency (ICRF) heating has been adopted in EAST tokamak as one of main auxiliary heating methods. The ICRF antenna usually consists of multiple launching elements because of limited port and space of tokamak device. Mutual coupling between straps has been observed in previous EAST ICRF current drive experiments. Due to adverse effects of such mutual coupling, many issues induced by cross power cannot be ignored, such as power imbalance in feed lines, high voltage standing wave ratio (VSWR), and etc. To restrain such mutual coupling, A device named decoupler was developed and tested in EAST ICRF system. According to the admittance matrix of load, three assembly positions (oscillation position, optimum position, and smooth position) along transmission line for the decoupler were taken into account and tested. The test results showed that ohmic dissipation in decoupler could not be neglected, which partly influenced the decoupling performance. The oscillation position and optimum position could restrain such adverse effects of ohmic dissipation and showed good decoupling performance. However, they cannot ensure the steady operation during H-mod due to the load variation. Finally, the smooth position has been adopted for EAST I port antenna because of steady decoupling performance comprised with engineering error and load resilience, which sincerely enhance the capability of system operation.
International Nuclear Information System (INIS)
Hoffman, D.J.; Baity, F.W.; Mayberry, M.J.; Swain, D.W.
1987-01-01
Low-power coupling tests have been carried out with a prototype ion cyclotron range of frequencies (ICRF) compact loop antenna on the DIII-D tokamak. Plasma load resistance values higher than originally calculated are measured in ohmic and L-mode, beam-heated plasmas. Load resistance decreases by a factor of ∼2 in H-mode operation. When edge localized modes (ELMs) occur, the antenna loading increases transiently to several ohms. Results indicate that fast-wave ICRF antenna coupling characteristics are highly sensitive to changes in the edge plasma profiles associated with the H-mode regime
ICRF-enhanced plasma potentials in the SOL of Alcator C-Mod
Energy Technology Data Exchange (ETDEWEB)
Ochoukov, R.; Whyte, D. G.; Brunner, D.; LaBombard, B.; Lipschultz, B.; Terry, J. L.; Wukitch, S. J. [PSFC MIT, NW17, 175 Albany Street, Cambridge, MA 02139 (United States); D' Ippolito, D. A.; Myra, J. R. [Lodestar Research Corporation, 2400 Central Avenue, Boulder, Colorado 80301 (United States)
2014-02-12
We performed an extensive survey of the plasma potential in the scrape-off layer (SOL) of Ion Cyclotron Range-of Frequencies (ICRF)-heated discharges on Alcator C-Mod. Our results show that plasma potentials are enhanced in the presence of ICRF power and plasma potential values of >100 V are often observed. Such potentials are high enough to induce sputtering of high-Z molybdenum (Mo) plasma facing components by deuterium ions on C-Mod. For comparison, the plasma potential in Ohmic discharges is typically less than 10 V, well below the threshold needed to induce Mo sputtering by deuterium ions. ICRF-enhanced plasma potentials are observed in the SOL regions that both magnetically map and do not map to active ICRF antennas. Regions that magnetically map to active ICRF antennas are accessible to slow waves directly launched by the antennas and these regions experience plasma potential enhancement that is partially consistent with the slow wave rectification mechanism. One of the most defining features of the slow wave rectification is a threshold appearance of significant plasma potentials (>100 V) when the dimensionless rectification parameter Λ{sub −o} is above unity and this trend is observed experimentally. We also observe ICRF-enhanced plasma potentials >100 V in regions that do not magnetically map to the active antennas and, hence, are not accessible for slow waves launched directly by the active antennas. However, unabsorbed fast waves can reach these regions. The general trend that we observe in these 'un-mapped' regions is that the plasma potential scales with the strength of the local RF wave fields with the fast wave polarization and the highest plasma potentials are observed in discharges with the highest levels of unabsorbed ICRF power. Similarly, we find that core Mo levels scale with the level of unabsorbed ICRF power suggesting a link between plasma potentials in the SOL and the strength of the impurity source.
Toroidal mode-conversion in the ICRF
International Nuclear Information System (INIS)
Jaun, A.; Hellsten, T.; Chiu, S.C.
1997-08-01
Mode-conversion is studied in the ion-cyclotron range of frequencies (ICRF) taking into account the toroidal geometry relevant for tokamaks. The global wavefields obtained using the gyrokinetic toroidal PENN code illustrate how the fast wave propagates to the neighborhood of the ion-ion hybrid resonance, where it is converted to a slow wave which deposits the wave energy through resonant interactions with the particles. The power deposition profiles obtained are dramatically different from the toroidal resonance absorption, showing that Budden's model is not a good approximation in the torus. Radially and poloidally localized wavefield structures characteristic of slow wave eigenmodes are predicted and could in experiments be driven to large amplitudes so as to interact efficiently with fast particles. (author) 5 figs., 1 tab., 48 refs
Full-wave solution of short impulses in inhomogeneous plasma
International Nuclear Information System (INIS)
Ferencz, Orsolya E.
2005-01-01
In this paper the problem of real impulse propagation in arbitrarily inhomogeneous media will be presented on a fundamentally new, general, theoretical way. The general problem of wave propagation of monochromatic signals in inhomogeneous media was enlightened. The earlier theoretical models for spatial inhomogeneities have some errors regarding the structure of the resultant signal originated from backward and forward propagating parts. The application of the method of inhomogeneous basic modes (MIBM) and the complete full-wave solution of arbitrarily shaped non-monochromatic plane waves in plasmas made it possible to obtain a better description of the problem, on a fully analytical way, directly from Maxwell's equations. The model investigated in this paper is inhomogeneous of arbitrary order (while the wave pattern can exist), anisotropic (magnetized), linear, cold plasma, in which the gradient of the one-dimensional spatial inhomogeneity is parallel to the direction of propagation. (author)
Energy Technology Data Exchange (ETDEWEB)
Uesaka, S [Kyoto University, Kyoto (Japan). Faculty of Engineering; Watanabe, T; Sassa, K [Kyoto University, Kyoto (Japan)
1997-05-27
Algorithm is constructed and a program developed for a full-wave inversion (FWI) method utilizing the elastic wave equation in seismic exploration. The FWI method is a method for obtaining a physical property distribution using the whole observed waveforms as the data. It is capable of high resolution which is several times smaller than the wavelength since it can handle such phenomena as wave reflection and dispersion. The method for determining the P-wave velocity structure by use of the acoustic wave equation does not provide information about the S-wave velocity since it does not consider S-waves or converted waves. In an analysis using the elastic wave equation, on the other hand, not only P-wave data but also S-wave data can be utilized. In this report, under such circumstances, an inverse analysis algorithm is constructed on the basis of the elastic wave equation, and a basic program is developed. On the basis of the methods of Mora and of Luo and Schuster, the correction factors for P-wave and S-wave velocities are formulated directly from the elastic wave equation. Computations are performed and the effects of the hypocenter frequency and vibration transmission direction are examined. 6 refs., 8 figs.
Expanding the operating space of ICRF on JET with a view to ITER
International Nuclear Information System (INIS)
Lamalle, P.U.; Bonheure, G.; Durodie, F.; Lerche, E.; Lyssoivan, A.; Van Eester, D.; Weyssow, B.; Mantsinen, M.J.; Heikkinen, J.; Salmi, A.; Santala, M.I.K.; Noterdaeme, J.M.; Bovkov, V.V.; Alper, B.; Beaumont, P.; Blackman, T.; Vries, P. de; Gowers, C.; Felton, R.; Kiptily, V.; Lawson, K.; Lomas, P.; Mayoral, M.L.; Monakhov, I.; Popovichev, S.; Sharapov, S.; Bertalot, L.; Castaldo, C.; Tardocchi, M.; La Luna, E. de; Eriksson, L.G.; Baar, M. de; Meo, F.; Mironov, M.; Nunes, I.; Piazza, G.; Noterdaeme, J.M.
2004-01-01
The paper reports on ITER-relevant ICRF (ion cyclotron resonance frequency) physics investigated on JET in 2003 and early 2004: minority heating of He 3 and D in H plasmas, minority heating of tritium in D, investigations of finite Larmor radius effects on the RF-induced high-energy tails, fast wave heating and current drive, and new results on the heating efficiency of ICRF antennas. ELM (edge localized mode) studies using fast RF measurements, experimental demonstration of a new ELM-tolerant antenna matching scheme, and technical enhancements planned on the JET ICRF system for 2005, themselves likewise strongly driven by the preparation for ITER, are also summarized. (authors)
Anti-alias filter in AORSA for modeling ICRF heating of DT plasmas in ITER
Berry, L. A.; Batchelor, D. B.; Jaeger, E. F.; RF SciDAC Team
2011-10-01
The spectral wave solver AORSA has been used extensively to model full-field, ICRF heating scenarios for DT plasmas in ITER. In these scenarios, the tritium (T) second harmonic cyclotron resonance is positioned near the magnetic axis, where fast magnetosonic waves are efficiently absorbed by tritium ions. In some cases, a fundamental deuterium (D) cyclotron layer can also be located within the plasma, but close to the high field boundary. In this case, the existence of multiple ion cyclotron resonances presents a serious challenge for numerical simulation because short-wavelength, mode-converted waves can be excited close to the plasma edge at the ion-ion hybrid layer. Although the left hand circularly polarized component of the wave field is partially shielded from the fundamental D resonance, some power penetrates, and a small fraction (typically LLC.
Realistic full wave modeling of focal plane array pixels.
Energy Technology Data Exchange (ETDEWEB)
Campione, Salvatore [Sandia National Laboratories (SNL-NM), Albuquerque, NM (United States). Electromagnetic Theory Dept.; Warne, Larry K. [Sandia National Laboratories (SNL-NM), Albuquerque, NM (United States). Electromagnetic Theory Dept.; Jorgenson, Roy E. [Sandia National Laboratories (SNL-NM), Albuquerque, NM (United States). Electromagnetic Theory Dept.; Davids, Paul [Sandia National Laboratories (SNL-NM), Albuquerque, NM (United States). Applied Photonic Microsystems Dept.; Peters, David W. [Sandia National Laboratories (SNL-NM), Albuquerque, NM (United States). Applied Photonic Microsystems Dept.
2017-11-01
Here, we investigate full-wave simulations of realistic implementations of multifunctional nanoantenna enabled detectors (NEDs). We focus on a 2x2 pixelated array structure that supports two wavelengths of operation. We design each resonating structure independently using full-wave simulations with periodic boundary conditions mimicking the whole infinite array. We then construct a supercell made of a 2x2 pixelated array with periodic boundary conditions mimicking the full NED; in this case, however, each pixel comprises 10-20 antennas per side. In this way, the cross-talk between contiguous pixels is accounted for in our simulations. We observe that, even though there are finite extent effects, the pixels work as designed, each responding at the respective wavelength of operation. This allows us to stress that realistic simulations of multifunctional NEDs need to be performed to verify the design functionality by taking into account finite extent and cross-talk effects.
2D full-wave simulation of waves in space and tokamak plasmas
Directory of Open Access Journals (Sweden)
Kim Eun-Hwa
2017-01-01
Full Text Available Simulation results using a 2D full-wave code (FW2D for space and NSTX fusion plasmas are presented. The FW2D code solves the cold plasma wave equations using the finite element method. The wave code has been successfully applied to describe low frequency waves in planetary magnetospheres (i.e., dipole geometry and the results include generation and propagation of externally driven ultra-low frequency waves via mode conversion at Mercury and mode coupling, refraction and reflection of internally driven field-aligned propagating left-handed electromagnetic ion cyclotron (EMIC waves at Earth. In this paper, global structure of linearly polarized EMIC waves is examined and the result shows such resonant wave modes can be localized near the equatorial plane. We also adopt the FW2D code to tokamak geometry and examine radio frequency (RF waves in the scape-off layer (SOL of tokamaks. By adopting the rectangular and limiter boundary, we compare the results with existing AORSA simulations. The FW2D code results for the high harmonic fast wave heating case on NSTX with a rectangular vessel boundary shows excellent agreement with the AORSA code.
Numerical solutions of ICRF fields in axisymmetric mirrors
International Nuclear Information System (INIS)
Phillips, M.W.
1985-01-01
The results of a new numerical code called GARFIELD (Grumman Aerospace Rf Field code) that calculates ICRF Fields in axisymmetric mirror geometry (such as the central cell of a tandem mirror or an RF test stand) are presented. The code solves the electromagnetic wave equation using a cold plasma dispersion relation with a small collision frequency to simulate absorption. The purpose of the calculation is to examine how ICRF wave structure and propagation is effected by the axial variation of the magnetic field in a mirror for various antenna designs. In the code the wave equation is solved in flux coordinates using a finite element method. This should allow more complex dielectric tensors to be modeled in the future. The resulting matrix is solved iteratively, to maximize the allowable size of the spatial grid. Results for a typical antenna array in a simple mirror will be shown
Design of full scale wave simulator for testing Power Take Off systems for wave energy converters
DEFF Research Database (Denmark)
Pedersen, H. C.; Hansen, R. H.; Hansen, Anders Hedegaard
2016-01-01
is therefore on the design and commissioning of a full scale wave simulator for testing PTO-systems for point absorbers. The challenge is to be able to design a system, which mimics the behavior of a wave when interacting with a given PTO-system – especially when considering discrete type PTO...
Full-wave calculation of fast-wave current drive in tokamaks including kparallel upshifts
International Nuclear Information System (INIS)
Jaeger, E.F.; Batchelor, D.B.
1991-01-01
Numerical calculations of fast-wave current drive (FWCD) efficiency have generally been of two types: ray tracing or global wave calculations. Ray tracing shows that the projection of the wave number (k parallel) along the magnetic field can vary greatly over a ray trajectory, particularly when the launch point is above or below the equatorial plane. As the wave penetrates toward the center of the plasma, k parallel increases, causing a decrease in the parallel phase speed and a corresponding decrease in the current drive efficiency, γ. But the assumptions of geometrical optics, namely short wavelength and strong single-pass absorption, are not greatly applicable in FWCD scenarios. Eigenmode structure, which is ignored in ray tracing, can play an important role in determining electric field strength and Landau damping rates. In such cases, a full-wave or global solution for the wave fields is desirable. In full-wave calculations such as ORION k parallel appear as a differential operator (rvec B·∇) in the argument of the plasma dispersion function. Since this leads to a differential system of infinite order, such codes of necessity assume k parallel ∼ k var-phi = const, where k var-phi is the toroidal wave number. Thus, it is not possible to correctly include effects of the poloidal magnetic field on k parallel. The problem can be alleviated by expressing the electric field as a superposition of poloidal modes, in which case k parallel is purely algebraic. This paper describes a new full-wave calculation, Poloidal Ion Cyclotron Expansion Solution, which uses poloidal and toroidal mode expansions to solve the wave equation in general flux coordinates. The calculation includes a full solution for E parallel and uses a reduced-order form of the plasma conductivity tensor to eliminate numerical problems associated with resolution of the very short wavelength ion Bernstein wave
2D full-wave simulation of waves in space and tokamak plasmas
Kim, Eun-Hwa; Bertelli, Nicola; Johnson, Jay; Valeo, Ernest; Hosea, Joel
2017-10-01
Simulation results using a 2D full-wave code (FW2D) for space and NSTX fusion plasmas are presented. The FW2D code solves the cold plasma wave equations using the finite element method. The wave code has been successfully applied to describe low frequency waves in planetary magnetospheres (i.e., dipole geometry) and the results include generation and propagation of externally driven ultra-low frequency waves via mode conversion at Mercury and mode coupling, refraction and reflection of internally driven field-aligned propagating left-handed electromagnetic ion cyclotron (EMIC) waves at Earth. In this paper, global structure of linearly polarized EMIC waves is examined and the result shows such resonant wave modes can be localized near the equatorial plane. We also adopt the FW2D code to tokamak geometry and examine radio frequency (RF) waves in the scape-off layer (SOL) of tokamaks. By adopting the rectangular and limiter boundary, we compare the results with existing AORSA simulations. The FW2D code results for the high harmonic fast wave heating case on NSTX with a rectangular vessel boundary shows excellent agreement with the AORSA code.
ICRF heating analysis on ASDEX plasmas
International Nuclear Information System (INIS)
Itoh, Sanae; Itoh, Kimitaka; Fukuyama, Atsushi; Morishita, Takayuki; Steinmetz, K.; Noterdaeme, J.-M.
1988-01-01
ICRF (ion cyclotron range of frequencies) waves heating in an ASDEX tokamak are analyzed. The excitation, propagation and absorption are studied by using a global wave code. This analysis is combined with a Fokker-Planck code. The waveform in the plasma, the loading resistance and the reactance of the antenna are calculated for both the minority ion heating and the second harmonic resonance heating. Attention is given to the change of the antenna loading associated with the L/H transition. Optimum conditions for the loading are discussed. In the minority heating case, the tail generation and thermalization are analyzed. Spatial profiles of the tail-ion temperature and the power transferred to the bulk electrons and ions are obtained. Central as well as off-central heating cases are investigated. The effect of the reactive electric field is discussed in connection with rf losses and impurity production. (author)
Full-waveform inversion of surface waves in exploration geophysics
Borisov, D.; Gao, F.; Williamson, P.; Tromp, J.
2017-12-01
Full-waveform inversion (FWI) is a data fitting approach to estimate high-resolution properties of the Earth from seismic data by minimizing the misfit between observed and calculated seismograms. In land seismics, the source on the ground generates high-amplitude surface waves, which generally represent most of the energy recorded by ground sensors. Although surface waves are widely used in global seismology and engineering studies, they are typically treated as noise within the seismic exploration community since they mask deeper reflections from the intervals of exploration interest. This is mainly due to the fact that surface waves decay exponentially with depth and for a typical frequency range (≈[5-50] Hz) sample only the very shallow part of the subsurface, but also because they are much more sensitive to S-wave than P-wave velocities. In this study, we invert surface waves in the hope of using them as additional information for updating the near surface. In a heterogeneous medium, the main challenge of surface wave inversion is associated with their dispersive character, which makes it difficult to define a starting model for conventional FWI which can avoid cycle-skipping. The standard approach to dealing with this is by inverting the dispersion curves in the Fourier (f-k) domain to generate locally 1-D models, typically for the shear wavespeeds only. However this requires that the near-surface zone be more or less horizontally invariant over a sufficient distance for the spatial Fourier transform to be applicable. In regions with significant topography, such as foothills, this is not the case, so we revert to the time-space domain, but aim to minimize the differences of envelopes in the early stages of the inversion to resolve the cycle-skipping issue. Once the model is good enough, we revert to the classic waveform-difference inversion. We first present a few synthetic examples. We show that classical FWI might be trapped in a local minimum even for
Full wave simulations of fast wave mode conversion and lower hybrid wave propagation in tokamaks
DEFF Research Database (Denmark)
Wright, J.C.; Bonoli, P.T.; Brambilla, M.
2004-01-01
Fast wave (FW) studies of mode conversion (MC) processes at the ion-ion hybrid layer in toroidal plasmas must capture the disparate scales of the FW and mode converted ion Bernstein and ion cyclotron waves. Correct modeling of the MC layer requires resolving wavelengths on the order of k...
Heat deposition on the first wall due to ICRF-induced loss of fast ions in JT-60U
International Nuclear Information System (INIS)
Kusama, Y.; Tobita, K.; Kimura, H.; Hamamatsu, K.; Fujii, T.; Nemoto, M.; Saigusa, M.; Moriyama, S.; Tani, K.; Koide, Y.; Sakasai, A.; Nishitani, T.; Ushigusa, K.
1995-01-01
In JT-60U, the heat deposition on the first wall due to the ICRF-induced loss of fast ions was investigated by changing the position of the resonance layer in the ripple-trapping region. A heat spot appears on the first wall of the same major radius as the resonance layer of the ICRF waves. The broadening of the heat spot in the major radius direction is consistent with that of the resonance layer due to the Doppler broadening. The heat spot is considered to be formed by the ICRF-induced ripple-trapped loss of fast ions. Although the total ICRF-induced loss power to the heat spot is as low as 2% of the total ICRF power, the additional heat flux will become a new issue because of the localized heat deposition on the first wall. ((orig.))
RF current distribution and topology of RF sheath potentials in front of ICRF antennae
International Nuclear Information System (INIS)
Colas, L.; Heuraux, S.; Bremond, S.; Bosia, G.
2005-01-01
The 2D (radial/poloidal) spatial topology of RF-induced convective cells developing radially in front of ion cyclotron range of frequency (ICRF) antennae is investigated, in relation to the spatial distribution of RF currents over the metallic structure of the antenna. This is done via a Green's function, determined from the ICRF wave coupling equations, and well-suited to open field lines extending toroidally far away on both sides of the antenna. Using such formalism, combined with a full-wave calculation using the 3D antenna code ICANT (Pecoul S. et al 2000 Comput. Phys. Commun. 146 166-87), two classes of convective cells are analysed. The first one appears in front of phased arrays of straps, and depending on the strap phasing, its topology is interpreted using the poloidal profiles of either the RF current or the RF voltage of the strip line theory. The other class of convective cells is specific to antenna box corners and is evidenced for the first time. Based on such analysis, general design rules are worked out in order to reduce the RF-sheath potentials, which generalize those proposed in the earlier literature, and concrete antenna design options are tested numerically. The merits of aligning all strap centres on the same (tilted) flux tube, and of reducing the antenna box toroidal conductivity in its lower and upper parts, are discussed
Current phase control test based on real-time measurement of impedance matrix of ICRF antennas
Energy Technology Data Exchange (ETDEWEB)
Saito, K., E-mail: saito@nifs.ac.jp [National Institute for Fusion Science, Toki, Gifu 509-5292 (Japan); Kumazawa, R.; Seki, T.; Kasahara, H.; Yokota, M.; Nomura, G.; Shimpo, F.; Mutoh, T. [National Institute for Fusion Science, Toki, Gifu 509-5292 (Japan)
2011-10-15
New ion cyclotron range of frequencies (ICRF) antennas have just been installed in the large helical device (LHD). These side-by-side ICRF antennas are symmetrical and designed to launch fast waves with various wave numbers parallel to the magnetic field line. The wave number can be controlled by changing the current phase on the straps; however, the mutual coupling between antennas changes antenna impedances, even if the plasma parameters are constant, leading to an increase in the reflected power. In addition to the current phase control, impedance matching devices must be tuned for the protection of tetrode tubes and efficient power injection. For this purpose, the impedance matrix of ICRF antennas must be determined, and it can be deduced from the forward and reflected waves at the outlet of the power amplifier by assuming geometric symmetry and reciprocity of the antennas. Using half-scale antennas, we successfully demonstrated simultaneous impedance matching and current phase control.
Possibility designing half-wave and full-wave molecular rectifiers by using single benzene molecule
Abbas, Mohammed A.; Hanoon, Falah H.; Al-Badry, Lafy F.
2018-02-01
This work focused on possibility designing half-wave and full-wave molecular rectifiers by using single and two benzene rings, respectively. The benzene rings were threaded by a magnetic flux that changes over time. The quantum interference effect was considered as the basic idea in the rectification action, the para and meta configurations were investigated. All the calculations are performed by using steady-state theoretical model, which is based on the time-dependent Hamiltonian model. The electrical conductance and the electric current are considered as DC output signals of half-wave and full-wave molecular rectifiers. The finding in this work opens up the exciting potential to use these molecular rectifiers in molecular electronics.
International Nuclear Information System (INIS)
Anton, Luis; MartI, Jose M; Ibanez, Jose M; Aloy, Miguel A.; Mimica, Petar; Miralles, Juan A.
2010-01-01
We obtain renormalized sets of right and left eigenvectors of the flux vector Jacobians of the relativistic MHD equations, which are regular and span a complete basis in any physical state including degenerate ones. The renormalization procedure relies on the characterization of the degeneracy types in terms of the normal and tangential components of the magnetic field to the wave front in the fluid rest frame. Proper expressions of the renormalized eigenvectors in conserved variables are obtained through the corresponding matrix transformations. Our work completes previous analysis that present different sets of right eigenvectors for non-degenerate and degenerate states, and can be seen as a relativistic generalization of earlier work performed in classical MHD. Based on the full wave decomposition (FWD) provided by the renormalized set of eigenvectors in conserved variables, we have also developed a linearized (Roe-type) Riemann solver. Extensive testing against one- and two-dimensional standard numerical problems allows us to conclude that our solver is very robust. When compared with a family of simpler solvers that avoid the knowledge of the full characteristic structure of the equations in the computation of the numerical fluxes, our solver turns out to be less diffusive than HLL and HLLC, and comparable in accuracy to the HLLD solver. The amount of operations needed by the FWD solver makes it less efficient computationally than those of the HLL family in one-dimensional problems. However, its relative efficiency increases in multidimensional simulations.
A two-phase full-wave superconducting rectifier
International Nuclear Information System (INIS)
Ariga, T.; Ishiyama, A.
1989-01-01
A two-phase full-wave superconducting rectifier has been developed as a small cryogenic power supply of superconducting magnets for magnetically levitation trains. Those magnets are operated in the persistent current mode. However, small ohmic loss caused at resistive joints and ac loss induced by the vibration of the train cannot be avoided. Therefore, the low-power cryogenic power supply is required to compensate for the reduction in magnet current. The presented superconducting rectifier consists of two identical full-wave rectifiers connected in series. Main components of each rectifier are a troidal shape superconducting set-up transformer and two thermally controlled switches. The test results using a 47.5 mH load magnet at 0.2 Hz and 0.5 Hz operations are described. To estimate the characteristics of the superconducting rectifier, the authors have developed a simulation code. From the experiments and the simulations, the transfer efficiency is examined. Furthermore, the optimal design of thermally controlled switches based on the finite element analysis is also discussed
Whistler Observations on DEMETER Compared with Full Electromagnetic Wave Simulations
Compston, A. J.; Cohen, M.; Lehtinen, N. G.; Inan, U.; Linscott, I.; Said, R.; Parrot, M.
2014-12-01
Terrestrial Very Low Frequency (VLF) electromagnetic radiation, which strongly impacts the Van Allen radiation belt electron dynamics, is injected across the ionosphere into the Earth's plasmasphere from two primary sources: man-made VLF transmitters and lightning discharges. Numerical models of trans-ionospheric propagation of such waves remain unvalidated, and early models may have overestimated the absorption, hindering a comprehensive understanding of the global impact of VLF waves in the loss of radiation belt electrons. In an attempt to remedy the problem of a lack of accurate trans-ionospheric propagation models, we have used a full electromagnetic wave method (FWM) numerical code to simulate the propagation of lightning-generated whistlers into the magnetosphere and compared the results with whistlers observed on the DEMETER satellite and paired with lightning stroke data from the National Lightning Detection Network (NLDN). We have identified over 20,000 whistlers occuring in 14 different passes of DEMETER over the central United States during the summer of 2009, and 14,000 of those occured within the 2000 km x 2000 km simulation grid we used. As shown in the attached figure, which shows a histogram of the ratio of the simulated whistler energy to the measured whistler energy for the 14,000 whistlers we compared, the simulation tends to slightly underestimate the total whistler energy injected by about 5 dB. However, the simulation underestimates the DEMETER measurements more as one gets further from the source lightning stroke, so since the signal to noise ratio of more distant whistlers will be smaller, possibly additive noise in the DEMETER measurements (which of course is not accounted for in the model) may explain some of the observed discrepancy.
Perspectives gained from ICRF physics studies on TFTR
International Nuclear Information System (INIS)
Phillips, C.K.; Bell, M.; Batha, S.
1998-01-01
The physics of ICRF heating and current drive has been studied on TFTR for over a decade. Following the early low power coupling studies, high power experiments resulted in sawtooth stabilization, the first observation of RF-driven excitation of toroidal Alfven eigenmodes, and the discovery of a mode conversion scenario for localized off-axis electron heating. The program culminated with the first studies of high power ICRF heating and profile control in tritium-rich high performance plasmas. A significant part of the concluding experiments centered on the potential of ICRF to drive sheared flows in order to suppress turbulence in the plasma core. Initial measurements taken with a novel poloidal velocity diagnostic suggest that localized sheared poloidal flows can be driven with ion Bernstein waves excited directly or else via mode conversion from a propagating fast magnetosonic wave. In this paper, recent results from TFTR on wave-based profile control techniques will be summarized along with suggestions for future studies elsewhere
Energy Technology Data Exchange (ETDEWEB)
Watanabe, T; Sassa, K [Kyoto University, Kyoto (Japan); Uesaka, S [Kyoto University, Kyoto (Japan). Faculty of Engineering
1996-10-01
The effect of initial models on full-wave inversion (FWI) analysis based on acoustic wave-equation was studied for elastic wave tomography of underground structures. At present, travel time inversion using initial motion travel time is generally used, and inverse analysis is conducted using the concept `ray,` assuming very high wave frequency. Although this method can derive stable solutions relatively unaffected by initial model, it uses only the data of initial motion travel time. FWI calculates theoretical waveform at each receiver using all of observed waveforms as data by wave equation modeling where 2-D underground structure is calculated by difference calculus under the assumption that wave propagation is described by wave equation of P wave. Although it is a weak point that FWI is easily affected by noises in an initial model and data, it is featured by high resolution of solutions. This method offers very excellent convergence as a proper initial model is used, resulting in sufficient performance, however, it is strongly affected by initial model. 2 refs., 7 figs., 1 tab.
Present and future JET ICRF antennae
International Nuclear Information System (INIS)
Kaye, A.; Brown, T.; Bhatnagar, V.; Crawley, P.; Jacquinot, J.; Lobel, R.; Plancoulaine, J.; Rebut, P.H.; Wade, T.; Walker, C.
1994-01-01
Since the initial operation of the JET ICRF system in 1985, up to 22 MW has been coupled to the plasma, many heating scenarios have been demonstrated and the main technological problem of RF-specific impurity production overcome. Many developments of the antennae have taken place over this period, notably the replacement of the water-cooled nickel screens with indirectly cooled beryllium screens, and the forthcoming installation of eight new A2 antennae for operation during the pumped divertor phase of JET. The A2 antennae include enhanced provision for fast wave current drive experiments on JET. This paper describes the beryllium screens, the technological results from operation and subsequent inspection of these screens, the design of the A2 antennae and the results from high power RF testing of a model of the A2 antenna. (orig.)
ICRF waveguide coupler research. Progress report, July 1983-July 1984
International Nuclear Information System (INIS)
Scharer, J.E.
1984-01-01
This report highlights results we have obtained on our ICRF (Ion Cyclotron Range of Frequencies) waveguide launcher research during the past year. We have completed an analysis of waveguide aperture launching of waves into a hot plasma with any prescribed edge density and temperature profile. The model Fourier analyzes the waveguide aperture fields and calculates the incident and reflected fast magnetosonic wave fields in the plasma edge region utilizing a stratified slab model. The requirement that the total wave fields at the waveguide-plasma interface match provides the boundary conditions which allow the solution for the plasma input impedance and reflection coefficient
Hybrid code simulation on mode conversion in the second harmonic ICRF heating
International Nuclear Information System (INIS)
Sakai, K.; Takeuchi, S.; Matsumoto, M.; Sugihara, R.
1985-01-01
ICRF second harmonic heating of a single-species plasma is studied by using a 1-1/2 dimensional quasi-neutral hybrid code. Mode conversion, transmission and reflection of the magnetosonic waves are confirmed, both for the high- and low-field-side excitations. The ion heating by waves propagating perpendicularly to the static magnetic field is also observed
High-efficiency passive full wave rectification for electromagnetic harvesters
Yilmaz, Mehmet; Tunkar, Bassam A.; Park, Sangtak; Elrayes, Karim; Mahmoud, Mohamed A. E.; Abdel-Rahman, Eihab; Yavuz, Mustafa
2014-10-01
We compare the performance of four types of full-wave bridge rectifiers designed for electromagnetic energy harvesters based on silicon diodes, Schottky diodes, passive MOSFETs, and active MOSFETs. Simulation and experimental results show that MOSFET-type rectifiers are more efficient than diode-type rectifiers, reaching voltage and power efficiency of 99% for ideal voltage source with input amplitudes larger than 800 mV. Since active MOSFETs require extra components and an external DC power supply, we conclude that passive MOSFETs are superior for micro-power energy harvesting systems. We demonstrate passive MOSFET rectifiers implemented using discrete, off-shelf components and show that they outperform all electromagnetic harvester rectifiers hitherto reported obtaining a power efficiency of 95%. Furthermore, we show that passive MOSFET rectifiers do not affect the center frequency, harvesting bandwidth, or optimal resistance of electromagnetic harvesters. We demonstrate a complete power management module by adding a capacitor to the rectifier output terminal. We found that this configuration changed the optimal resistive load from 40 Ω to 55 Ω and decreased output power efficiency to 86%.
Full wave simulation of waves in ECRIS plasmas based on the finite element method
Energy Technology Data Exchange (ETDEWEB)
Torrisi, G. [INFN - Laboratori Nazionali del Sud, via S. Sofia 62, 95123, Catania, Italy and Università Mediterranea di Reggio Calabria, Dipartimento di Ingegneria dell' Informazione, delle Infrastrutture e dell' Energia Sostenibile (DIIES), Via Graziella, I (Italy); Mascali, D.; Neri, L.; Castro, G.; Patti, G.; Celona, L.; Gammino, S.; Ciavola, G. [INFN - Laboratori Nazionali del Sud, via S. Sofia 62, 95123, Catania (Italy); Di Donato, L. [Università degli Studi di Catania, Dipartimento di Ingegneria Elettrica Elettronica ed Informatica (DIEEI), Viale Andrea Doria 6, 95125 Catania (Italy); Sorbello, G. [INFN - Laboratori Nazionali del Sud, via S. Sofia 62, 95123, Catania, Italy and Università degli Studi di Catania, Dipartimento di Ingegneria Elettrica Elettronica ed Informatica (DIEEI), Viale Andrea Doria 6, 95125 Catania (Italy); Isernia, T. [Università Mediterranea di Reggio Calabria, Dipartimento di Ingegneria dell' Informazione, delle Infrastrutture e dell' Energia Sostenibile (DIIES), Via Graziella, I-89100 Reggio Calabria (Italy)
2014-02-12
This paper describes the modeling and the full wave numerical simulation of electromagnetic waves propagation and absorption in an anisotropic magnetized plasma filling the resonant cavity of an electron cyclotron resonance ion source (ECRIS). The model assumes inhomogeneous, dispersive and tensorial constitutive relations. Maxwell's equations are solved by the finite element method (FEM), using the COMSOL Multiphysics{sup ®} suite. All the relevant details have been considered in the model, including the non uniform external magnetostatic field used for plasma confinement, the local electron density profile resulting in the full-3D non uniform magnetized plasma complex dielectric tensor. The more accurate plasma simulations clearly show the importance of cavity effect on wave propagation and the effects of a resonant surface. These studies are the pillars for an improved ECRIS plasma modeling, that is mandatory to optimize the ion source output (beam intensity distribution and charge state, especially). Any new project concerning the advanced ECRIS design will take benefit by an adequate modeling of self-consistent wave absorption simulations.
Full-wave solution of short impulses in inhomogeneous plasma
Indian Academy of Sciences (India)
... in arbitrarily inhomogeneous media will be presented on a fundamentally new, ... The general problem of wave propagation of monochromatic signals in inhomogeneous media was enlightened in [1]. ... Pramana – Journal of Physics | News.
EAST ICRF system for long pulse operation
International Nuclear Information System (INIS)
Zhao, Y.P.; Zhang, X.J.; Mao, Y.Z.
2013-01-01
Radio frequency (RF) power in the ion cyclotron range of frequencies (ICRF) is one of the primary auxiliary heating techniques for Experimental Advanced Superconducting Tokamak (EAST). A 6.0 MW ICRF systems in the range of 25-70 MHz has been put into operation during the EAST 2012 spring campaign. The ICRF systems consist of two port-mounted antennas and each antenna is driven by two independent 1.5 MW RF power source. Another four 1.5 MW ICRF system is under way of construction.The system will deliver more than 10 MW of RF power to the plasma for 1000 sec pulse length. This paper gives brief introduction of the ICRF systems capability on EAST. (author)
Modelling and Testing of Wave Dragon Wave Energy Converter Towards Full Scale Deployment
DEFF Research Database (Denmark)
Parmeggiani, Stefano
-commercial stage in which it has proven difficult to secure the necessary funding for the deployment of a full-scale demonstrator unit. The work presented aims at easing this process, by increasing public and scientific knowledge of the device, as well as by showing the latest progress in its development. Research....... This is mainly due to the development of an updated overtopping model specifically suited to Wave Dragon, which allows greater quality to predictions of the primary energy absorption of the device compared to previous versions. At the same time an equitable approach has been described and used in the performance......, the research has also provided a deeper insight into the physics of the overtopping process by individually assessing the influence of related device configuration and wave features, which goes beyond the present application and may be used for other overtopping WECs as well. Comprehensive analysis...
The Role of Combined ICRF and NBI Heating in JET Hybrid Plasmas in Quest for High D-T Fusion Yield
Directory of Open Access Journals (Sweden)
Mantsinen Mervi
2017-01-01
Full Text Available Combined ICRF and NBI heating played a key role in achieving the world-record fusion yield in the first deuterium-tritium campaign at the JET tokamak in 1997. The current plans for JET include new experiments with deuterium-tritium (D-T plasmas with more ITER-like conditions given the recently installed ITER-like wall (ILW. In the 2015-2016 campaigns, significant efforts have been devoted to the development of high-performance plasma scenarios compatible with ILW in preparation of the forthcoming D-T campaign. Good progress was made in both the inductive (baseline and the hybrid scenario: a new record JET ILW fusion yield with a significantly extended duration of the high-performance phase was achieved. This paper reports on the progress with the hybrid scenario which is a candidate for ITER longpulse operation (∼1000 s thanks to its improved normalized confinement, reduced plasma current and higher plasma beta with respect to the ITER reference baseline scenario. The combined NBI+ICRF power in the hybrid scenario was increased to 33 MW and the record fusion yield, averaged over 100 ms, to 2.9x1016 neutrons/s from the 2014 ILW fusion record of 2.3x1016 neutrons/s. Impurity control with ICRF waves was one of the key means for extending the duration of the high-performance phase. The main results are reviewed covering both key core and edge plasma issues.
Full-wave simulations of current profiles for fast magnetosonic wave current drive
International Nuclear Information System (INIS)
Dmitrieva, M.V.; Eriksson, L.-G.; Gambier, D.J.
1992-12-01
Numerical simulations of current drive in tokamaks by fast waves (FWCD) have been performed in the range of the ion cyclotron and at lower frequencies via 3-Dimensional numerical code ICTOR. Trapped particles effects were taken into account in the calculation of the fast wave current drive efficiency and the bootstrap current generation. The global efficiency of FWCD if found to be γ∼ 0.1 x 10 20 AW -1 m -2 for the Joint European Torus tokamak (JET) parameters at a central electron temperature of ∼ 10 kev. The efficiency of FWCD for reactor-like plasmas is found to be γ∼0.3 x 10 20 AW -1 m -2 for ∼ 100% of FWCD and γ∼ 1 x 10 20 AW -1 m -2 for FWCD and ∼ 65% of bootstrap in a total current of ∼ 25MA at a 25kev central temperature with a density of ∼10 20 m -3 and major radius R ∼ 8m. Non-inductive current density profiles are studied. Broad FWCD current profiles are obtained for flat reactor temperature and density profiles with bootstrap current concentrated at the plasma edge. The possibility of a steady-state reactor on full wave (FW) with a large fraction of bootstrap current is discussed. It appears to be impractical to rely on such an external current driven (CD) scheme for a reactor as long a γ is less than 2 x 10 20 AW -1 m -2 . (Author)
AORSA full wave calculations of helicon waves in DIII-D and ITER
Lau, C.; Jaeger, E. F.; Bertelli, N.; Berry, L. A.; Green, D. L.; Murakami, M.; Park, J. M.; Pinsker, R. I.; Prater, R.
2018-06-01
Helicon waves have been recently proposed as an off-axis current drive actuator for DIII-D, FNSF, and DEMO tokamaks. Previous ray tracing modeling using GENRAY predicts strong single pass absorption and current drive in the mid-radius region on DIII-D in high beta tokamak discharges. The full wave code AORSA, which is valid to all order of Larmor radius and can resolve arbitrary ion cyclotron harmonics, has been used to validate the ray tracing technique. If the scrape-off-layer (SOL) is ignored in the modeling, AORSA agrees with GENRAY in both the amplitude and location of driven current for DIII-D and ITER cases. These models also show that helicon current drive can possibly be an efficient current drive actuator for ITER. Previous GENRAY analysis did not include the SOL. AORSA has also been used to extend the simulations to include the SOL and to estimate possible power losses of helicon waves in the SOL. AORSA calculations show that another mode can propagate in the SOL and lead to significant (~10%–20%) SOL losses at high SOL densities. Optimizing the SOL density profile can reduce these SOL losses to a few percent.
ICRF current drive by using antenna phase control
International Nuclear Information System (INIS)
Kishimoto, Y.; Itoh, K.
1987-01-01
A global analysis of current drive in tokamaks by using waves in the ion cyclotron range of frequencies (ICRF), considering the entire antenna-plasma system, is presented. A phase shifted antenna array is used to inject toroidal momentum into the electrons. Within the context of quasi-linear theory, a Fokker-Planck calculation is combined with an ICRF wave propagation-absorption analysis which includes kinetic effects and realistic boundary conditions. The radial profile of the current induced by the mode converted ion Bernstein wave and by the magnetosonic fast wave is obtained, together with the global current drive efficiency (total induced current/total emitted power from the antennas) in the high density and temperature plasma regime. The phase dependence of the global efficiency is investigated by changing the launching conditions such as the total antenna number and the antenna spacing. In medium size tokamaks, the electron power absorption and the associated driven current are found to be affected considerably by the plasma cavity resonance. It is also found that the global efficiency is sensitive to the antenna spacing. When the antenna spacing is increased, the global efficiency is reduced by counter current generation. (author)
Interaction of ICRF power and edge plasma in Tore Supra ergodic divertor configuration
International Nuclear Information System (INIS)
Nguyen, F.; Grosman, A.; Basiuk, V.; Fraboulet, D.; Beaumont, B.; Becoulet, A.; Ghendrih, Ph.; Ladurelle, L.; Meslin, B.
2000-01-01
The coupling of ICRF power to plasma is a crucial problem in Tore Supra for high power and long pulse operations and depends greatly on the edge parameters, in particular on the edge density. Conversely, the behaviour of the bulk plasma is related to the edge conditions and the injection of RF power also induces major modifications on the edge plasma. Moreover, the Ergodic Divertor (ED) of Tore Supra imposes a complex configuration at the edge due to the presence of the magnetic perturbation. Several diagnostics are available to study the interaction of ICRF power with the edge plasma: Langmuir probes on the ED modules, infra red (IR) cameras, charge exchange neutral analysers. In minority heating scheme, the edge density is very sensitive to any perturbation in the high recycling regime which is always found in the ED configuration for relevant plasma parameters. Partially detached regimes, with or without inhomogeneities of density and temperature induced by the flux tubes of the laminar layer, are obtained for high resistance coupling values. The coupling is then not very robust and feedback control or antenna automatic matching techniques are developed. In fast wave electron heating scheme with ED, various fast wave absorption mechanisms (minority heating, Mode Conversion, Alfven resonance) are present at the plasma edge due to the large size of the plasma. The ICRF coupling is difficult due to the low fast wave direct electron damping, even with high hydrogen minority scheme. An increase of the injected ICRF power could improve this situation
ICRF [Ion Cyclotron Range of Frequencies] heating and antenna coupling in a high beta tokamak
International Nuclear Information System (INIS)
Elet, R.S.
1988-01-01
Maxwell's Equations are solved in two-dimensions for the electromagnetic fields in a toroidal cavity using the cold plasma fluid dielectric tensor in the Ion Cyclotron Range of Frequencies (ICRF). The Vector Wave Equation is transformed to a set of two, coupled second-order partial differential equations with inhomogeneous forcing functions which model a wave launcher. The resulting equations are finite differenced and solved numerically with a complex banded matrix algorithm on a Cray-2 computer using a code described in this report. This code is used to study power coupling characteristics of a wave launcher for low and high beta tokamaks. The low and high beta equilibrium tokamak magnetic fields applied in this model are determined from analytic solutions to the Grad-Shafranov equation. The code shows good correspondence with the results of low field side ICRF heating experiments performed on the Tokamak of Fontenay-Aux-Roses (TFR). Low field side and high field side antenna coupling properties for ICRF heating in the Columbia High Beta Tokamak (HBT) experiment are calculated with this code. Variations of antenna position in the tokamak, ionic concentration and plasma density, and volume-averaged beta have been analyzed for HBT. It is found that the location of the antenna with respect to the plasma has the dominant role in the design of an ICRF heating experiment in HBT. 10 refs., 52 figs., 13 tabs
ICRF Review: From ERASMUS To ITER
Weynants, R. R.
2009-11-01
This is a personal account of how I saw ICRF evolve since 1974, with a presentation that is ordered according to the topics: heating, antenna coupling, impurity generation/mitigation and system technology. The nature of the main issues is each time reviewed, recent findings are incorporated, and it is shown how the ICRF community has been able to react to sometimes rapidly changing demands and is indeed resolutely preparing ITER.
ICRF heating experiments in JFT-2 tokamak
International Nuclear Information System (INIS)
Matsumoto, Hiroshi
1986-01-01
This is an experimental study of ICRF heating on JFT-2 Tokamak in Japan Atomic Energy Research Institute. In this study, we first clarified physical and engineering problems of ICRF heating of tokamak plasma. Next, we optimized the design of the ICRF heating system, and the plasma parameters for the heating. Finally, we could demonstrate a high efficiency of this additional heating method by launching RF power which is two or three times as large as an ohmic input power to a plasma. And we achieved following things. (1) We optimized a design of an antenna, and we improved a durability of the system for high voltage. With the result that we achieved the maximum power density on an antenna. (2) We demonstrated that electron heating regime and ion heating regime can be easily accessed by controlling plasma parameters. Also we found the optimum heating conditions in each heating regime. (3) We experimentally clarified the production mechanism of impurities during ICRF heating. We could reduce the influx of metal impurity ions to a plasma by employing low z materials for limiters and antenna shields. Consequently, we improved a heating efficiency of electrons. Next, we studied a power balance of plasma during ICRF heating, and we could compare heating characteristics of ICRF with other additional heatings on JFT-2. (author)
International Nuclear Information System (INIS)
Hoffman, D.J.; Colestock, P.L.; Gardner, W.L.; Hosea, J.C.; Nagy, A.; Stevens, J.; Swain, D.W.; Wilson, J.R.
1988-01-01
Two compact loop antennas have been designed to provide ion cyclotron resonant frequency (ICRF) heating for TFTR. The antennas can convey a total of 10 MW to accomplish core heating in either high-density or high-temperature plasmas. The near-term goal of heating TFTR plasmas and the longer-term goals of ease in handling (for remote maintenance) and high reliability (in an inaccessible tritium tokamak environment) were major considerations in the antenna designs. The compact loop configuration facilitates handling because the antennas fit completely through their ports. Conservative design and extensive testing were used to attain the reliability required for TFTR. This paper summarizes how these antennas will accomplish these goals. 5 figs, 1 tab
Modelling of combined ICRF and NBI heating in JET hybrid plasmas
Directory of Open Access Journals (Sweden)
Gallart Dani
2017-01-01
Full Text Available During the 2015-2016 JET campaigns many efforts have been devoted to the exploration of high performance plasma scenarios envisaged for ITER operation. In this paper we model the combined ICRF+NBI heating in selected key hybrid discharges using PION. The antenna frequency was tuned to match the cyclotron frequency of minority hydrogen (H at the center of the tokamak coinciding with the second harmonic cyclotron resonance of deuterium. The modelling takes into account the synergy between ICRF and NBI heating through the second harmonic cyclotron resonance of deuterium beam ions which allows us to assess its impact on the neutron rate RNT. We evaluate the influence of H concentration which was varied in different discharges in order to test their role in the heating performance. According to our modelling, the ICRF enhancement of RNT increases by decreasing the H concentration which increases the ICRF power absorbed by deuterons. We find that in the recent hybrid discharges this ICRF enhancement was in the range of 10-25%. Finally, we extrapolate the results to D-T and find that the best performing hybrid discharges correspond to an equivalent fusion power of ∼7.0 MW in D-T.
ICRF heating and current drive experiments on TFTR
International Nuclear Information System (INIS)
Rogers, J.H.; Hosea, J.C.; Phillips, C.K.
1996-01-01
Recent experiments in the Ion Cyclotron Range of Frequencies (ICRF) at TFTR have focused on the RF physics relevant to advanced tokamak D-T reactors. Experiments performed either tested confinement in reactor relevant plasmas or tested specific ICRF heating scenarios under consideration for reactors. H-minority heating was used to supply identical heating sources for matched D-T and D only L-mode plasmas to determine the species scaling for energy confinement. Second harmonic tritium heating was performed with only thermal tritium ions in an L-mode target plasma, verifying a possible start-up scenario for the International Thermonuclear Experimental Reactor (ITER). Direct electron heating in Enhanced Reverse Shear (ERS) plasmas has been found to delay the back transition out of the ERS state. D-T mode conversion of the fast magnetosonic wave to an Ion Berstein Wave (IBW) for off-axis heating and current drive has been successfully demonstrated for the first time. Parasitic Li 7 cyclotron damping limited the fraction of the power going to the electrons to less than 30%. Similar parasitic damping by Be 9 could be problematic in ITER. Doppler shifted fundamental resonance heating of beam ions and alpha particles has also been observed
International Nuclear Information System (INIS)
Valeo, Ernest; Johnson, Jay R.; Kim, Eun-Hwa; Phillips, Cynthia
2012-01-01
A wide variety of plasma waves play an important role in the energization and loss of particles in the inner magnetosphere. Our ability to understand and model wave-particle interactions in this region requires improved knowledge of the spatial distribution and properties of these waves as well as improved understanding of how the waves depend on changes in solar wind forcing and/or geomagnetic activity. To this end, we have developed a two-dimensional, finite element code that solves the full wave equations in global magnetospheric geometry. The code describes three-dimensional wave structure including mode conversion when ULF, EMIC, and whistler waves are launched in a two-dimensional axisymmetric background plasma with general magnetic field topology. We illustrate the capabilities of the code by examining the role of plasmaspheric plumes on magnetosonic wave propagation; mode conversion at the ion-ion and Alfven resonances resulting from external, solar wind compressions; and wave structure and mode conversion of electromagnetic ion cyclotron waves launched in the equatorial magnetosphere, which propagate along the magnetic field lines toward the ionosphere. We also discuss advantages of the finite element method for resolving resonant structures, and how the model may be adapted to include nonlocal kinetic effects.
International Nuclear Information System (INIS)
Bahar, E.
1976-01-01
The propagation of electromagnetic waves excited by electric dipoles oriented along the axis of multilayered spheroidal structures of finite conductivity is investigated. The electromagnetic parameters and the thickness of the layers of the structure are assumed to be functions of the latitude. In the analysis, electric and magnetic field transforms that constitute a discrete and a continuous spectrum of spherical waves are used to provide a suitable basis for the expansion of the electromagnetic fields at any point in the irregular spheroidal structure. For spheroidal structures with good conducting cores, the terms in the solutions associated with the continuous part of the wave spectrum vanish. In general, however, when the skin depth for the core is large compared to its dimensions or when the sources are located in the core of the structure and propagation in the core is of special interest, the contribution from the continuous part of the wave spectrum cannot be neglected. At each interface between the layers of the irregular spheroidal structure, exact boundary conditions are imposed. Since the terms of the field expansions in the irregular structure do not individually satisfy the boundary conditions, Maxwell's equations are reduced to sets of coupled ordinary first-order differential equations for the wave amplitudes. The solutions are shown to satisfy the reciprocity relationships in electromagnetic theory. The analysis may be applied to problems of radio wave propagation in a nonuniform model of the earth-ionosphere waveguide, particularly when focusing effects at the antipodes are important
Multi-directional plasmonic surface-wave splitters with full bandwidth isolation
International Nuclear Information System (INIS)
Gao, Zhen; Gao, Fei; Zhang, Baile
2016-01-01
We present a multidirectional plasmonic surface-wave splitter with full bandwidth isolation experimentally based on coupled defect surface modes in a surface-wave photonic crystal. In contrast to conventional plasmonic surface-wave frequency splitters with polaritonic dispersion relations that overlap at low frequencies, this multidirectional plasmonic surface-wave splitter based on coupled defect surface modes can split different frequency bands into different waveguide branches without bandwidth overlap. Transmission spectra and near-field imaging measurements have been implemented in the microwave frequencies to verify the performance of the multidirectional plasmonic surface-wave splitter. This surface wave structure can be used as a plasmonic wavelength-division multiplexer that may find potential applications in the surface-wave integrated circuits from microwave to terahertz frequencies.
A full wave code for ion cyclotron waves in toroidal plasmas
International Nuclear Information System (INIS)
Brambilla, M.
1996-02-01
The code TORIC solves the finite Larmor radius wave equations in the ion cyclotron frequency range in arbitrary axisymmetric toroidal geometry. The model used describes the compressional and torsional Alfven waves (or, depending on the parallel phase velocity, the kinetic counterpart of the latter), and ion Bernstein waves excited by mode conversion near the first ion cyclotron harmonic. In the ion response the broadening of the absorption regions due to the finite width of the cyclotron resonance of individual ions in toroidal geometry is taken into account. The parallel component of the wave electric field is evaluated on the same footing as the transverse ones; the response of the electrons includes Landau damping, Transit Time damping and the mixed term. The numerical approach uses a spectral representation of the solution in the poloidal angle θ, and cubic finite elements in the radial variable ψ. Great flexibility is provided in the way ion Bernstein waves excited by mode conversion are damped when their wavelength becomes comparable with the ion Larmor radius, in the regularization of Alfven resonances, and in the treatment of the outer plasma layers. As an option, we have also implemented the Order Reduction Algorithm, which provides a particularly fast, yet accurate evaluation of the power deposition profiles in toroidal geometry. Thee present report describes the model and its numerical implementation, and provides the information needed to use the code. A few examples illustrating applications of TORIC are also included. (orig.)
Reflection and transmission of full-vector X-waves normally incident on dielectric half spaces
Salem, Mohamed
2011-08-01
The reflection and transmission of full-vector X-Waves incident normally on a planar interface between two lossless dielectric half-spaces are investigated. Full-vector X-Waves are obtained by superimposing transverse electric and magnetic polarization components, which are derived from the scalar X-Wave solution. The analysis of transmission and reflection is carried out via a straightforward but yet effective method: First, the X-Wave is decomposed into vector Bessel beams via the Bessel-Fourier transform. Then, the reflection and transmission coefficients of the beams are obtained in the spectral domain. Finally, the transmitted and reflected X-Waves are obtained via the inverse Bessel-Fourier transform carried out on the X-wave spectrum weighted with the corresponding coefficient. © 2011 IEEE.
Plasma-surface interactions with ICRF antennas and lower hybrid grills in Tore Supra
International Nuclear Information System (INIS)
Harris, J.H.; Hutter, T.; Hogan, J.T.; Basiuk, V.; Beaumont, B.; Becoulet, A.; Bremond, S.; Carter, M.D.; Goniche, M.; Goulding, R.H.; Guilhem, D.; Haste, G.R.; Hoffman, D.J.; Litaudon, X.; Nguyen, F.
1997-01-01
The edge plasma interactions of the actively cooled radio-frequency heating launchers in Tore Supra ion-cyclotron range of frequencies (ICRF) antennas and lower-hybrid (LH) grills are studied using infrared video imaging. On the two-strap ICRF antennas, operated in fast-wave electron heating or current drive mode, hot spots with temperatures of 500-900 C are observed by the end of 2 s power pulses of 2 MW per antenna. The steady-state temperature distribution is determined principally by the relative phase of the two antenna straps: dipole (heating) phasing results in significantly less antenna heating than does 90 (current drive) phasing. Transient heat fluxes of 1-20 MW/m 2 are measured on the lateral protection bumpers at ICRF turn-on; these fluxes are primarily a function of plasma and radio frequency (rf) control. The remarkable feature of the lower hybrid edge interaction is the production of beams of heat flux in front of the grills; these beams propagate along the helical magnetic field lines and can deliver fluxes of 5-10 MW/m 2 over areas of several cm 2 to plasma-facing components. Both the ICRF and LH phenomena appear to result from the acceleration of particles by the near fields of the launchers. Modeling of the heat flux deposition on components and its relation to sputtering processes is presented. (orig.)
Database of full-scale laboratory experiments on wave-driven sand transport processes
van der Werf, Jebbe J.; Schretlen, Johanna Lidwina Maria; Ribberink, Jan S.; O'Donoghue, Tom
2009-01-01
A new database of laboratory experiments involving sand transport processes over horizontal, mobile sand beds under full-scale non-breaking wave and non-breaking wave-plus-current conditions is described. The database contains details of the flow and bed conditions, information on which quantities
Reflection and transmission of normally incident full-vector X waves on planar interfaces
Salem, Mohamed; Bagci, Hakan
2011-01-01
The reflection and transmission of full-vector X waves normally incident on planar half-spaces and slabs are studied. For this purpose, X waves are expanded in terms of weighted vector Bessel beams; this new decomposition and reconstruction method
Stability of Planar Rarefaction Wave to 3D Full Compressible Navier-Stokes Equations
Li, Lin-an; Wang, Teng; Wang, Yi
2018-05-01
We prove time-asymptotic stability toward the planar rarefaction wave for the three-dimensional full, compressible Navier-Stokes equations with the heat-conductivities in an infinite long flat nozzle domain {R × T^2} . Compared with one-dimensional case, the proof here is based on our new observations on the cancellations on the flux terms and viscous terms due to the underlying wave structures, which are crucial for overcoming the difficulties due to the wave propagation in the transverse directions x 2 and x 3 and its interactions with the planar rarefaction wave in x 1 direction.
SOL RF physics modelling in Europe, in support of ICRF experiments
Directory of Open Access Journals (Sweden)
Colas Laurent
2017-01-01
Full Text Available A European project was undertaken to improve the available SOL ICRF physics simulation tools and confront them with measurements. This paper first reviews code upgrades within the project. Using the multi-physics finite element solver COMSOL, the SSWICH code couples RF full-wave propagation with DC plasma biasing over “antenna-scale” 2D (toroidal/radial domains, via non-linear RF and DC sheath boundary conditions (SBCs applied at shaped plasma-facing boundaries. For the different modules and associated SBCs, more elaborate basic research in RF-sheath physics, SOL turbulent transport and applied mathematics, generally over smaller spatial scales, guides code improvement. The available simulation tools were applied to interpret experimental observations on various tokamaks. We focus on robust qualitative results common to several devices: the spatial distribution of RF-induced DC bias; left-right asymmetries over strap power unbalance; parametric dependence and antenna electrical tuning; DC SOL biasing far from the antennas, and RF-induced density modifications. From these results we try to identify the relevant physical ingredients necessary to reproduce the measurements, e.g. accurate radiated field maps from 3D antenna codes, spatial proximity effects from wave evanescence in the near RF field, or DC current transport. Pending issues towards quantitative predictions are also outlined.
Detection of sinkholes or anomalies using full seismic wave fields : phase II.
2016-08-01
A new 2-D Full Waveform Inversion (FWI) software code was developed to characterize layering and anomalies beneath the ground surface using seismic testing. The software is capable of assessing the shear and compression wave velocities (Vs and Vp) fo...
Zhang, Xiao-bo; Tan, Jun; Song, Peng; Li, Jin-shan; Xia, Dong-ming; Liu, Zhao-lun
2017-01-01
The gradient preconditioning approach based on seismic wave energy can effectively avoid the huge storage consumption in the gradient preconditioning algorithms based on Hessian matrices in time-domain full waveform inversion (FWI), but the accuracy
Full-waveform inversion with reflected waves for 2D VTI media
Pattnaik, Sonali; Tsvankin, Ilya; Wang, Hui; Alkhalifah, Tariq
2016-01-01
Full-waveform inversion in anisotropic media using reflected waves suffers from the strong non-linearity of the objective function and trade-offs between model parameters. Estimating long-wavelength model components by fixing parameter perturbations
JUNO E/J/SS WAVES CALIBRATED SURVEY FULL RESOLUTION V1.0
National Aeronautics and Space Administration — The Juno Waves calibrated full resolution survey data set includes all low rate science electric spectral densities from 50Hz to 41MHz and magnetic spectral...
3D electromagnetic theory of ICRF multi PORT multi loop antenna
International Nuclear Information System (INIS)
Vdovin, V.L.; Kamenskij, I.V.
1997-01-01
In this report the theory of three dimensional antenna in Ion Cyclotron Resonance Frequency (ICRF) is developed for a plasma with circular magnetic surfaces. The multi loop antenna is located in ITER several ports. Circular plasma and antenna geometry provides new important tools to account for: 1) right loading antenna impedance matrix calculation urgently needed for a matching of RF generator with an antenna; 2) right calculation of an antenna toroidal and poloidal excited spectra because the DIFFRACTION, refraction and REFLECTION effects for the Fast Waves (FW) are in FIRST time are included self consistently in 3D ICRF antenna - plasma treatment; 3) right calculation of RF power deposition profiles because self consistently found 3D antenna - plasma FW excited spectra in non slab plasma model are important ones in a weakly dissipated plasma for Fast Waves (even for ITER parameters). (J.P.N.)
Reflection and transmission of normally incident full-vector X waves on planar interfaces
Salem, Mohamed
2011-12-23
The reflection and transmission of full-vector X waves normally incident on planar half-spaces and slabs are studied. For this purpose, X waves are expanded in terms of weighted vector Bessel beams; this new decomposition and reconstruction method offers a more lucid and intuitive interpretation of the physical phenomena observed upon the reflection or transmission of X waves when compared to the conventional plane-wave decomposition technique. Using the Bessel beam expansion approach, we have characterized changes in the field shape and the intensity distribution of the transmitted and reflected full-vector X waves. We have also identified a novel longitudinal shift, which is observed when a full-vector X wave is transmitted through a dielectric slab under frustrated total reflection condition. The results of our studies presented here are valuable in understanding the behavior of full-vector X waves when they are utilized in practical applications in electromagnetics, optics, and photonics, such as trap and tweezer setups, optical lithography, and immaterial probing. © 2011 Optical Society of America.
ICRF antenna modeling and simulation. Final report, March 1, 1993--May 31, 1996
Energy Technology Data Exchange (ETDEWEB)
NONE
1996-08-30
SAIC has undergone a three year research and development program in support of the DOE Office of Fusion Energy`s (OFE) program in Ion Cyclotron Range of Frequencies (ICRF) heating of present, next generation, and future plasma fusion devices. The effort entailed advancing theoretical models and numerical simulation technology of ICRF physics and engineering issues associated predominately with, but not limited to, tokamak Ion Cyclotron Heating (ICH) and fast wave current drive (FWCD). Ion cyclotron heating and current drive is a central element in all current and planned large fusion experiments. In recent years, the variety of uses for ICRF systems has expanded, and includes the following: (1) Heating sufficient to drive plasma to ignition. (a) Second-harmonic T heating. (b) He{sup 3} minority heating. (2) Second-harmonic He{sup 4} heating in H plasma (for non-activated phase). (3) Detailed equilibrium profile control minority heating. (a) Ion minority (He{sup 3}) CD (for profile control on inside of plasma). (b) Ion minority (He{sup 3}) CD (for profile control on outside of plasma). (4) Ion-ion hybrid regime majority ion heating. (5) Electron current drive. (6) Mode conversion to drive current. (7) Deuterium minority heating. (8) Sawtooth instability stabilization. (9) Alpha particle parameter enhancement. (10) The generation of minority tails by ICRF to simulate D-T plasma particle physics in a deuterium plasma. Optimization of ICRF antenna performance for either heating or current drive depends critically on the complex balance and interplay between the plasma physics and the electromechanical system requirements. For example, ITER IC rf designs call for an IC. system frequency range from 20 MHz to 100 MHz. Additionally, antenna designs and operational modes that minimize impurity production and induced sheath formation may degrade current drive efficiency. Such effects have been observed in experiments involving it versus zero antenna phasing.
ICRF antenna modeling and simulation. Final report, March 1, 1993--May 31, 1996
International Nuclear Information System (INIS)
1996-01-01
SAIC has undergone a three year research and development program in support of the DOE Office of Fusion Energy's (OFE) program in Ion Cyclotron Range of Frequencies (ICRF) heating of present, next generation, and future plasma fusion devices. The effort entailed advancing theoretical models and numerical simulation technology of ICRF physics and engineering issues associated predominately with, but not limited to, tokamak Ion Cyclotron Heating (ICH) and fast wave current drive (FWCD). Ion cyclotron heating and current drive is a central element in all current and planned large fusion experiments. In recent years, the variety of uses for ICRF systems has expanded, and includes the following: (1) Heating sufficient to drive plasma to ignition. (a) Second-harmonic T heating. (b) He 3 minority heating. (2) Second-harmonic He 4 heating in H plasma (for non-activated phase). (3) Detailed equilibrium profile control minority heating. (a) Ion minority (He 3 ) CD (for profile control on inside of plasma). (b) Ion minority (He 3 ) CD (for profile control on outside of plasma). (4) Ion-ion hybrid regime majority ion heating. (5) Electron current drive. (6) Mode conversion to drive current. (7) Deuterium minority heating. (8) Sawtooth instability stabilization. (9) Alpha particle parameter enhancement. (10) The generation of minority tails by ICRF to simulate D-T plasma particle physics in a deuterium plasma. Optimization of ICRF antenna performance for either heating or current drive depends critically on the complex balance and interplay between the plasma physics and the electromechanical system requirements. For example, ITER IC rf designs call for an IC. system frequency range from 20 MHz to 100 MHz. Additionally, antenna designs and operational modes that minimize impurity production and induced sheath formation may degrade current drive efficiency. Such effects have been observed in experiments involving it versus zero antenna phasing
ICRF stabilization of sawteeth on TFTR
International Nuclear Information System (INIS)
Phillips, C.K.; Hosea, J.; Stevens, J.; Wilson, J.R.; Bell, M.; Bitter, M.; Cheng, C.Z.; Darrow, D.; Fredrickson, E.; Hammett, G.W.; Hill, K.; Hsuan, H.; Jassby, D.; McCune, D.; McGuire, K.; Owens, D.K.; Park, H.; Ramsey, A.; Schilling, G.; Schivell, J.; Stratton, B.; Synakowski, E.; Taylor, G.; Towner, H.; White, R.; Zweben, S.; Phillips, M.W.; Hughes, M.; Bush, C.; Goldfinger, R.; Hoffman, D.; Houlberg, W.; Nagayama, Y.; Smithe, D.N.
1992-01-01
Results obtained from experiments utilizing high power ICRF (ion cyclotron range of frequency) heating to stabilize sawtooth oscillations on TFTR are reviewed. The key observations include existence of a minimum ICRF power required to achieve stabilization, a dependence of the stabilization threshold on the relative size of the ICRF power deposition profile to the q=1 volume, and a peaking of the equilibrium pressure and current profiles during sawtooth-free phases of the discharges. In addition, preliminary measurements of the poloidal magnetic field profile indicate that q on axis decreases to a value of 0.55±0.15 after a sawtooth-stabilized period of ∼0.5 sec has transpired. The results are discussed in the context of theory, which suggests that the fast ions produced by the ICRF heating suppress sawteeth by stabilizing the m=1 MHD instabilities believed to be the trigger for the sawtooth oscillations. Though qualitative agreement is found between the observations and the theory, further refinement of the theory coupled with more accurate measurements of experimental profiles will be required in order to complete quantitative comparisons
An algorithm for the calculation of three-dimensional ICRF fields in tokamak geometry
International Nuclear Information System (INIS)
Smithe, D.N.; Kammash, T.
1987-01-01
A computational scheme is developed which permits tractable calculation of three-dimensional full-wave solutions to the Vlasov-Maxwell equations under typical ion cyclotron range of frequencies (ICRF) experimental conditions. The method is unique in that power deposition to the plasma is determined via the anti-Hermitian part of a truncated warm plasma dielectric operator, rather than as the result of an assumed phenomenological collision frequency. The resulting computer code allows arbitrary variation of density, temperature, magnetic field and minority concentration in the poloidal plane by performing a convolution of poloidal modes to produce a coupled system of differential equations in the radial variable. By assuming no inhomogeneity along the toroidal axis, an inverse transform over k parallel is performed, yielding the global three-dimensional fast wave field solutions. The application of the code to TFTR-like plasmas shows a mild resonance structure in antenna loading related to the changing number of wavelengths between the antenna and the resonance layer. (author)
ICRF heating experiments on JIPP T-II
International Nuclear Information System (INIS)
Ichimura, M.; Fujita, J.; Hirokura, S.
1983-10-01
Data of JIPP T-II ICRF heating experiments are presented. The experiment covers three typical cases: the low concentration hydrogen minority case, the high concentration hydrogen minority case, and the 3 He minority case. The best heating efficiency is obtained for the 3 Heminority case. It is shown through power balance analysis that the two H-minority cases are different in the wave energy deposition profile. The difference is explained by the presence of local cavity mode for the high concentration minority case. The ion temperature stops rising at the power density level of 0.65 W/cm 3 . An analytic solution of the Fokker-Planck equation is derived to interpret the deterioration of heating efficiency. (author)
Pelamis wave energy converter. Verification of full-scale control using a 7th scale model
Energy Technology Data Exchange (ETDEWEB)
NONE
2005-07-01
The Pelamis Wave Energy Converter is a new concept for converting wave energy for several applications including generation of electric power. The machine is flexibly moored and swings to meet the water waves head-on. The system is semi-submerged and consists of cylindrical sections linked by hinges. The mechanical operation is described in outline. A one-seventh scale model was built and tested and the outcome was sufficiently successful to warrant the building of a full-scale prototype. In addition, a one-twentieth scale model was built and has contributed much to the research programme. The work is supported financially by the DTI.
Directory of Open Access Journals (Sweden)
Denis A.
2006-11-01
Full Text Available Les outils acoustiques de dernière génération permettent maintenant d'enregistrer l'ensemble des ondes générées par une source acoustique à l'intérieur d'une géométrie cylindrique telle qu'un puits de sondage. Le train d'onde qu'il est alors possible d'analyser se compose successivement de trois composantes majeures (l'onde de compression, de cisaillement et de Stoneley dont nous avons une représentation pour chaque position de la sonde à l'intérieur du puits. Nous présentons, dans ce texte, trois méthodes originales et rapides (calculs possibles sur le site même pour identifier, à partir du traitement de l'onde de Stoneley, les fractures ouvertes recoupées par un forage. Nous donnons, dans un premier temps, nos motivations pour le choix unique du traitement de l'onde de Stoneley pour, dans un deuxième temps, exposer les trois méthodes développées et montrer pour chacune d'entre elles une application pratique. Interest in recognizing and identifying fractures in a coherent formation for the petroleum, geothermal and storage (oil and gas, wastes sectors has led to the development of indirect prospection methods inside boreholes such as acoustic logging. The latest acoustic tools are capable of recording all waves generated by an acoustic logging tool inside a cyclindrical geometry such as a borehole. The wavetrain that can then be analyzed is successively made up of three major components (the P compression wave, the S shear wave and the Stoneley wave for which we have a representation for each position of the logging tool in the borehole. An example of a recording is shown in Fig. 1. Because of its specific features (high amplitudes, low frequency, high signal-to-noise ratio, the Stoneley wave is recognized to be a good indicator of open fractures. Therefore, we use simple digital processing to quantify the influence of fracturing on the propagation of the Stoneley wave. Three methods stemming from the digital processing of
Current Mode Full-Wave Rectifier Based on a Single MZC-CDTA
Directory of Open Access Journals (Sweden)
Neeta Pandey
2013-01-01
Full Text Available This paper presents a current mode full-wave rectifier based on single modified Z copy current difference transconductance amplifier (MZC-CDTA and two switches. The circuit is simple and is suitable for IC implementation. The functionality of the circuit is verified with SPICE simulation using 0.35 μm TSMC CMOS technology parameters.
A Novel Current-Mode Full-Wave Rectifier Based on One CDTA and Two Diodes
Directory of Open Access Journals (Sweden)
F. Khateb
2010-09-01
Full Text Available Precision rectifiers are important building blocks for analog signal processing. The traditional approach based on diodes and operational amplifiers (OpAmps exhibits undesirable effects caused by limited OpAmp slew rate and diode commutations. In the paper, a full-wave rectifier based on one CDTA and two Schottky diodes is presented. The PSpice simulation results are included.
Monte Carlo simulation study of the ICRF minority heating in the Large Helical Device
International Nuclear Information System (INIS)
Murakami, S.; Okamoto, M.; Nakajima, N.; Ohnishi, M.; Okada, H.
1993-10-01
A Monte Carlo simulation code is developed for the ICRF heating in helical systems, which takes into account finite beta effects, complicated orbits of high energetic particles, Coulomb collisions, and interactions between the particles and the applied waves. The code is used to investigate the ICRF minority heating in the Large Helical Device. The configuration of the magnetic fields changes significantly due to finite beta effects in the Large Helical Device. The resonance layer position is found to be crucial to the heating efficiency as the plasma beta increases. When the strength of the resonance magnetic field is set to the value at the magnetic axis, the higher heat efficiency is obtained and no clear difference of the heat efficiency due to the finite beta effects is found at the high ICRF wave power region. However the radial profile of the transferred power to majority ions and electrons from minority ions changes by the deformation of the trapped particle orbits due to the finite beta effects. The heat efficiency is improved if the radial electric field, E r , is positive (E r is directed radially outward) and it is also improved by supplying 3 He minority ions rather than proton minority ions. (author)
Monte Carlo simulation study of ICRF minority heating in the large helical device
International Nuclear Information System (INIS)
Murakami, S.; Okamoto, M.; Ohnishi, M.; Okada, H.
1994-01-01
A Monte Carlo simulation code is developed for ion cyclotron range of frequencies (ICRF) heating in helical systems, which takes into account finite beta effects, complicated orbits of high energetic particles, Coulomb collisions and interactions between particles and the applied waves. The code is used to investigate ICRF minority heating in the Large Helical Device (LHD). The configuration of the magnetic fields changes significantly due to finite beta effects in the LHD. The resonance layer position is found to be crucial to the heating efficiency as the plasma beta increases. When the strength of the resonance magnetic field is set to the value at the magnetic axis, a higher heat efficiency is obtained and no clear difference of the heat efficiency due to finite beta effects is found in the high ICRF wave power region. However, the radial profile of the power transferred to majority ions and electrons from minority ions changes because of the deformation of the trapped particle due to the finite beta effects. The heat efficiency is improved if the radial electric field, E r , is positive (E r is directed radially outward) and it is also improved by supplying 3 He minority ions rather than proton minority ions. (author). 26 refs, 11 figs, 2 tabs
Recent developments in ICRF antenna modelling
International Nuclear Information System (INIS)
Lamalle, P.U.; Messiaen, A.M.; Dumortier, P.; Louche, F.
2005-01-01
The antennas presently developed for ICRF heating of the ITER plasma consist of a tightly packed array of a large number of radiating straps, in order to deliver a high power density without exceeding radio-frequency voltage standoffs. Recently developed commercial software has enabled important progress in the coupling analysis and optimisation of such demanding systems. Approximations allowing to convincingly include a realistic plasma description in these codes are discussed. Application of the resulting numerical tools is illustrated by simulation of the existing JET A2 ICRF array, with the goal to validate simulations for future antennas. Advances in the design of realistic test bed conditions, using salted water as a means of creating plasma-relevant antenna loading, and the appropriate scaling of a mockup are also presented. (author)
International Nuclear Information System (INIS)
Gambier, D.J.; Evrard, M.P.; Adam, J.
1990-01-01
The power deposition profile in the ion cyclotron range of frequencies (ICRF) has been investigated experimentally in JET by means of a square wave modulated RF perturbation. The study has been conducted in D(H) and D( 3 He) plasmas for two heating scenarios. In D( 3 He) plasmas and for central heating in a scenario where mode conversion to Bernstein waves is accessible, the direct power deposition profile on electrons has been derived. It accounts for 15% of the total coupled power and extends over 25% of the minor radius. Outside the RF power deposition zone, the electron thermal diffusivity χ e inside the inversion radius surface (r i ) can be estimated through observation of the diffusive electronic transport. In discharges without monster sawteeth and for a low central temperature gradient (∇T e (r ≤ r i ) ≤ ∇T e (r ≥ r i ) approx. = 5 keV·m -1 ) the value obtained is small (approx. =0.24 +- 0.05 m 2 · s -1 ), typically ten times lower than χ e values deduced from heat pulse propagation in similar discharges at radii larger than the inversion radius. For the D(H) minority heating scheme, a large fraction of the ICRF modulated power is absorbed by minority ions, and the minority tail is modulated with a characteristic ion-electron (i-e) slowing-down time. In this scheme, electron heating occurs only through collisions with the minority ion tail and no modulation of the electron temperature is observed in sawtoothing discharges. This is interpreted as a consequence of the long i-e equipartition time, acting as an integrator for the modulated ICRF signal. Finally, a correlation between the time of the sawtooth crash and the periodic turn-off of the ICRF power is found and its consequence for modulation experiments is reviewed. (author). 22 refs, 16 figs
Gravitational wave emission from a bounded source: A treatment in the full nonlinear regime
International Nuclear Information System (INIS)
Oliveiral, H.P. de; Damiao Soares, I.
2004-03-01
The dynamics of a bounded gravitational collapsing configuration emitting gravitational waves is studied. The exterior spacetime is described by Robinson-Trautman geometries and have the Schwarzschild black hole as its final gravitational configuration, when the gravitational wave emission ceases. The full nonlinear regime is examined by using the Galerkin method that allows us to reduce the equations governing the dynamics to a finite-dimensional dynamical system, after a proper truncation procedure. Gravitational wave emission patterns from given initial configurations are exhibited for several phases of the collapse and the mass-loss ratio that characterizes the amount of mass extracted by the gravitational wave emission is evaluated. We obtain that the smaller initial mass M init of the configuration, the more rapidly the Schwarzschild solution is attained and a larger fraction of M init is lost in the process of gravitational wave emission. Within all our numerical experiments, the distribution of the mass fraction extracted by gravitational wave emission is shown to satisfy the distribution law of nonextensive statistics and this result is independent of the initial configurations considered. (author)
Full wave dc-to-dc converter using energy storage transformers
Moore, E. T.; Wilson, T. G.
1969-01-01
Full wave dc-to-dc converter, for an ion thrustor, uses energy storage transformers to provide a method of dc-to-dc conversion and regulation. The converter has a high degree of physical simplicity, is lightweight and has high efficiency.
Monte-Carlo Orbit/Full Wave Simulation of Fast Alfven Wave (FW) Damping on Resonant Ions in Tokamaks
International Nuclear Information System (INIS)
Choi, M.; Chan, V.S.; Pinsker, R.I.; Tang, V.; Bonoli, P.; Wright, J.
2005-01-01
To simulate the resonant interaction of fast Alfven wave (FW) heating and Coulomb collisions on energetic ions, including finite orbit effects, a Monte-Carlo code ORBIT-RF has been coupled with a 2D full wave code TORIC4. ORBIT-RF solves Hamiltonian guiding center drift equations to follow trajectories of test ions in 2D axisymmetric numerical magnetic equilibrium under Coulomb collisions and ion cyclotron radio frequency quasi-linear heating. Monte-Carlo operators for pitch-angle scattering and drag calculate the changes of test ions in velocity and pitch angle due to Coulomb collisions. A rf-induced random walk model describing fast ion stochastic interaction with FW reproduces quasi-linear diffusion in velocity space. FW fields and its wave numbers from TORIC are passed on to ORBIT-RF to calculate perpendicular rf kicks of resonant ions valid for arbitrary cyclotron harmonics. ORBIT-RF coupled with TORIC using a single dominant toroidal and poloidal wave number has demonstrated consistency of simulations with recent DIII-D FW experimental results for interaction between injected neutral-beam ions and FW, including measured neutron enhancement and enhanced high energy tail. Comparison with C-Mod fundamental heating discharges also yielded reasonable agreement
Efficient full wave code for the coupling of large multirow multijunction LH grills.
Czech Academy of Sciences Publication Activity Database
Preinhaelter, Josef; Hillairet, J.; Milanesio, D.; Maggiora, R.; Urban, Jakub; Vahala, L.; Vahala, G.
2017-01-01
Roč. 57, č. 11 (2017), č. článku 116060. ISSN 0029-5515 R&D Projects: GA MŠk(CZ) 8D15001; GA MŠk(CZ) LM2015045 Institutional support: RVO:61389021 Keywords : lower hybrid waves * coupling * large multirow multijunction grills * tokamak * full-wave Subject RIV: BL - Plasma and Gas Discharge Physics OBOR OECD: Fluids and plasma physics (including surface physics) Impact factor: 3.307, year: 2016 http://iopscience.iop.org/article/10.1088/1741-4326/aa7f4f/meta
Neutral axis determination of full size concrete structures using coda wave measurements
Jiang, Hanwan; Zhan, Hanyu; Zhuang, Chenxu; Jiang, Ruinian
2018-03-01
Coda waves experiencing multiple scattering behaviors are sensitive to weak changes occurring in media. In this paper, a typical four-point bending test with varied external loads is conducted on a 30-meter T-beam that is removed from a bridge after being in service for 15 years, and the coda wave signals are collected with a couple of sources-receivers pairs. Then the observed coda waves at different loads are compared to calculate their relative velocity variations, which are utilized as the parameter to distinct the compression and tensile zones as well as determine the neutral axis position. Without any prior knowledge of the concrete beam, the estimated axis position agrees well with the associated strain gage measurement results, and the zones bearing stress and tension behaviors are indicated. The presented work offers significant potential for Non-Destructive Testing and Evaluation of full-size concrete structures in future work.
A Full-Wave Seismic Tomography for the Crustal Structure in the Metropolitan Beijing Region
Sun, A.; Zhao, L.; Chen, Q.
2008-12-01
The greater Beijing metropolitan region is located in an old cratonic block in northeast China with complex geology and several large historic earthquakes, such as the Sanhe-Pinggu earthquake (~M8.0) in 1679, the Xingtai earthquake (M7.2) in 1966, and the Tangshan earthquake (M7.8) in 1976. To enhance our understanding of the crustal structure and the seismotectonics under this region, we conduct a full-wave three-dimensional (3D) tomographic study of this region using the waveforms recorded by the newly established Beijing metropolitan digital seismic network. Since the Beijing network was put into operation in October 2001, there have been 89 local earthquakes of magnitude 3.0 and above. From these, we selected 23 events of magnitude 3.2 and above and obtained their waveform records at 50 stations within our area of interest. The types of instruments at these stations include broadband, short-period and very broadband. First-motion focal mechanisms were determined for these events. We used a regional 3D model obtained by seismic reflection surveys as the reference model and calculated the synthetic seismograms by the finite-difference method. In this first attempt at finite- frequency tomography for the Beijing region, we focus on the variation of the P-wave speed using the first- arriving P waves. We measure the frequency-dependent traveltime anomalies of the P waves by the cross- correlation between observed and synthetic P waveforms within several discrete frequency bands between 20-sec and 5-sec periods. The sensitivity or Frechet kernels of these measurements for the perturbations in P-wave speed were computed by the same finite-difference method. We will present the preliminary result in our full-wave seismic tomography for the Beijing region.
Zhang, Xiao-bo
2017-06-01
The gradient preconditioning approach based on seismic wave energy can effectively avoid the huge storage consumption in the gradient preconditioning algorithms based on Hessian matrices in time-domain full waveform inversion (FWI), but the accuracy is affected by the energy of reflected waves when strong reflectors are present in velocity model. To address this problem, we propose a gradient preconditioning method, which scales the gradient based on the energy of the “approximated transmitted wavefield” simulated by the nonreflecting acoustic wave equation. The method does not require computing or storing the Hessian matrix or its inverse. Furthermore, it can effectively eliminate the effects caused by geometric diffusion and non-uniformity illumination on gradient. The results of model experiments confirm that the time-domain FWI using the gradient preconditioning based on transmitted waves energy can achieve higher inversion precision for high-velocity body and the deep strata below when compared with using the gradient preconditioning based on seismic waves energy.
Local full-wave energy and quasilinear analysis in nonuniform plasmas
International Nuclear Information System (INIS)
Smithe, D.N.
1989-01-01
The subject of local wave energy in plasmas is treated via quasilinear theory from the dual perspectives of the action-angle formalism and gyrokinetic analysis. An extension is presented to all orders in the gyroradius of the self-consistent wave-propagation/quasilinear-absorption problem using gyrokinetics. Questions of when and under what conditions local energy should be of definite sign are answered using the action-angle formalism. An important result is that the ''dielectric operators'' of the linearized wave equation and of the local energy are not the same, a fact which is obscured when the eikonal or WKB assumption is invoked. Even though the two dielectrics are very different in character, it is demonstrated that they are nevertheless related by a simple mathematical statement. This study was originally motivated by concern over the question of local energy for r.f.-heating of plasmas, where in certain instances, full-wave effects such as refraction, strong absorption, and mode conversion are of primary importance. Fundamentally, the r.f.-absorption must equate with the energy moment of the quasilinear term to achieve a correct energy balance. This fact governs the derivation (as opposed to postulation) of the local absorption. The troublesome ''kinetic flux'' may then be chosen (it is not unique) to satisfy a wave-energy balance relation with the Poynting flux and local absorption. It is shown that at least one such choice reduces asymptotically to the Stix form away from nonuniformities. (author)
Directory of Open Access Journals (Sweden)
Luca Pierantoni
2012-11-01
Full Text Available We report on full-wave techniques in the frequency (energy-domain and the time-domain, aimed at the investigation of the combined electromagnetic-coherent transport problem in carbon based nanostructured materials and devices viz. graphene nanoribbons. The frequency-domain approach is introduced in order to describe a Poisson-Schrödinger / Dirac system in a quasi static framework. Thetime-domain approach deals with the full-wave solution of the combined Maxwell-Schrödinger / Dirac system of equations. From the above theoretical platforms, home-made solvers are provided, aimed atdealing with challenging problems in realistic devices / systems environments, typical of the area of radio-frequency nanoelectronics.
Plasma-surface interactions with ICRF antennas and lower hybrid grills in Tore Supra
Energy Technology Data Exchange (ETDEWEB)
Harris, J.H. [Oak Ridge National Lab., TN (United States); Hutter, T. [Association Euratom-CEA, Centre d`Etudes de Cadarache, 13 - Saint-Paul-lez-Durance (France). Dept. de Recherches sur la Fusion Controlee; Hogan, J.T. [Oak Ridge National Lab., TN (United States)] [and others
1996-10-01
The edge plasma interactions of the actively cooled radio-frequency heating launchers in Tore Supra- ion-cyclotron range-of-frequencies (ICRF) antennas and lower-hybrid (LH) grills-are studied using infrared video imaging. On the two-strap ICRF antennas, operated in fast-wave electron heating or current drive mode, hot spots with temperatures of 500-900{degrees} C are observed by the end of 2-s power pulses of 2 MW per antenna. The distribution and maximum values of temperature are determined principally by the relative phase of the two antenna straps: dipole (heating) phasing results in significantly less antenna heating than does 90` (current drive) phasing. Transient heat fluxes of 1-20 MW/m{sup 2} are measured on the lateral protection bumpers at ICRF turn-on; these fluxes are primarily a function of plasma and radio frequency (rf) control, and are not simply correlated with the strap phasing or the final surface temperature distributions. The remarkable feature of the lower hybrid edge interaction is the production of beams of heat flux in front of the grills; these beams propagate along the helical magnetic field lines and can deliver fluxes of 5-10 MW/m{sup 2} over areas of several cm{sup 2} to plasma-facing components such as the grill or antenna lateral bumpers. Both the ICRF and LH phenomena appear to result from the acceleration of particles by the near fields of the launchers. Modeling of the heat flux deposition on components and its relation to sputtering processes is presented, and possibilities for controlling these interactions are discussed.
Full-Wave Ambient Noise Tomography of the Long Valley Volcanic Region (California)
Flinders, A. F.; Shelly, D. R.; Dawson, P. B.; Hill, D. P.; Shen, Y.
2017-12-01
In the late 1970s, and throughout the 1990s, Long Valley Caldera (California) experienced intense periods of unrest characterized by uplift of the resurgent dome, earthquake swarms, and CO2 emissions around Mammoth Mountain. While modeling of the uplift and gravity changes support the possibility of new magmatic intrusions beneath the caldera, geologic interpretations conclude that the magmatic system underlying the caldera is moribund. Geophysical studies yield diverse versions of a sizable but poorly resolved low-velocity zone at depth (> 6km), yet whether this zone is indicative of a significant volume of crystal mush, smaller isolated pockets of partial melt, or magmatic fluids, is inconclusive. The nature of this low-velocity zone, and the state of volcano's magmatic system, carry important implications for the significance of resurgent-dome inflation and the nature of associated hazards. To better characterize this low-velocity zone we present preliminary results from a 3D full-waveform ambient-noise seismic tomography model derived from the past 25 years of vertical component broadband and short-period seismic data. This new study uses fully numerical solutions of the wave equation to account for the complex wave propagation in a heterogeneous, 3D earth model, including wave interaction with topography. The method ensures that wave propagation is modeled accurately in 3D, enabling the full use of seismic records. By using empirical Green's functions, derived from ambient noise and modeled as Rayleigh surface waves, we are able to extend model resolution to depths beyond the limits of previous local earthquake studies. The model encompasses not only the Long Valley Caldera, but the entire Long Valley Volcanic Region, including Mammoth Mountain and the Mono Crater/Inyo Domes volcanic chain.
Quasi-Resonant Full-Wave Zero-Current Switching Buck Converter Design, Simulation and Application
Yanik, G.; Isen, E.
2015-01-01
—This paper presents a full wave quasi-resonant zerocurrent switching buck converter design, simulation and application. The converter control uses with zero-current switching (ZCS) technique to decrease the switching losses. Comparing to conventional buck converter, resonant buck converter includes a resonant tank equipped with resonant inductor and capacitor. The converter is analyzed in mathematical for each subintervals. Depending on the desired input and output electrical quantities, con...
Brossier, Romain; Zhou, Wei; Operto, Stéphane; Virieux, Jean
2015-04-01
Full Waveform Inversion (FWI) is an appealing method for quantitative high-resolution subsurface imaging (Virieux et al., 2009). For crustal-scales exploration from surface seismic, FWI generally succeeds in recovering a broadband of wavenumbers in the shallow part of the targeted medium taking advantage of the broad scattering-angle provided by both reflected and diving waves. In contrast, deeper targets are often only illuminated by short-spread reflections, which favor the reconstruction of the short wavelengths at the expense of the longer ones, leading to a possible notch in the intermediate part of the wavenumber spectrum. To update the velocity macromodel from reflection data, image-domain strategies (e.g., Symes & Carazzone, 1991) aim to maximize a semblance criterion in the migrated domain. Alternatively, recent data-domain strategies (e.g., Xu et al., 2012, Ma & Hale, 2013, Brossier et al., 2014), called Reflection FWI (RFWI), inspired by Chavent et al. (1994), rely on a scale separation between the velocity macromodel and prior knowledge of the reflectivity to emphasize the transmission regime in the sensitivity kernel of the inversion. However, all these strategies focus on reflected waves only, discarding the low-wavenumber information carried out by diving waves. With the current development of very long-offset and wide-azimuth acquisitions, a significant part of the recorded energy is provided by diving waves and subcritical reflections, and high-resolution tomographic methods should take advantage of all types of waves. In this presentation, we will first review the issues of classical FWI when applied to reflected waves and how RFWI is able to retrieve the long wavelength of the model. We then propose a unified formulation of FWI (Zhou et al., 2014) to update the low wavenumbers of the velocity model by the joint inversion of diving and reflected arrivals, while the impedance model is updated thanks to reflected wave only. An alternate inversion of
Ion cyclotron emission calculations using a 2D full wave numerical code
International Nuclear Information System (INIS)
Batchelor, D.B.; Jaeger, E.F.; Colestock, P.L.
1987-01-01
Measurement of radiation in the HF band due to cyclotron emission by energetic ions produced by fusion reactions or neutral beam injection promises to be a useful diagnostic on large devices which are entering the reactor regime of operation. A number of complications make the modelling and interpretation of such measurements difficult using conventional geometrical optics methods. In particular the long wavelength and lack of high directivity of antennas in this frequency regime make observation of a single path across the plasma into a viewing dump impractical. Pickup antennas effectively see the whole plasma and wall reflection effects are important. We have modified our 2D full wave ICRH code 2 to calculate wave fields due to a distribution of energetic ions in tokamak geometry. The radiation is modeled as due to an ensemble of localized source currents distributed in space. The spatial structure of the coherent wave field is then calculated including cyclotron harmonic damping as compared to the usual procedure of incoherently summing powers of individual radiators. This method has the advantage that phase information from localized radiating currents is globally retained so the directivity of the pickup antennas is correctly represented. Also standing waves and wall reflections are automatically included
Universal Voltage Conveyor and Current Conveyor in Fast Full-Wave Rectifier
Directory of Open Access Journals (Sweden)
Josef Burian
2012-12-01
Full Text Available This paper deals about the design of a fast voltage-mode full-wave rectifier, where universal voltage conveyor and second-generation current conveyor are used as active elements. Thanks to the active elements, the input and output impedance of the non-linear circuit is infinitely high respectively zero in theory. For the rectification only two diodes and three resistors are required as passive elements. The performance of the circuit is shown on experimental measurement results showing the dynamic range, time response, frequency dependent DC transient value and RMS error for different values of input voltage amplitudes.
Current and Voltage Conveyors in Current- and Voltage-Mode Precision Full-Wave Rectifiers
Directory of Open Access Journals (Sweden)
J. Koton
2011-04-01
Full Text Available In this paper new versatile precision full-wave rectifiers using current and/or voltage conveyors as active elements and two diodes are presented. The performance of these circuit solutions is analysed and compared to the opamp based precision rectifier. To analyze the behavior of the functional blocks, the frequency dependent RMS error and DC transient value are evaluated for different values of input voltage amplitudes. Furthermore, experimental results are given that show the feasibilities of the conveyor based rectifiers superior to the corresponding operational amplifier based topology.
Visco-elastic controlled-source full waveform inversion without surface waves
Paschke, Marco; Krause, Martin; Bleibinhaus, Florian
2016-04-01
We developed a frequency-domain visco-elastic full waveform inversion for onshore seismic experiments with topography. The forward modeling is based on a finite-difference time-domain algorithm by Robertsson that uses the image-method to ensure a stress-free condition at the surface. The time-domain data is Fourier-transformed at every point in the model space during the forward modeling for a given set of frequencies. The motivation for this approach is the reduced amount of memory when computing kernels, and the straightforward implementation of the multiscale approach. For the inversion, we calculate the Frechet derivative matrix explicitly, and we implement a Levenberg-Marquardt scheme that allows for computing the resolution matrix. To reduce the size of the Frechet derivative matrix, and to stabilize the inversion, an adapted inverse mesh is used. The node spacing is controlled by the velocity distribution and the chosen frequencies. To focus the inversion on body waves (P, P-coda, and S) we mute the surface waves from the data. Consistent spatiotemporal weighting factors are applied to the wavefields during the Fourier transform to obtain the corresponding kernels. We test our code with a synthetic study using the Marmousi model with arbitrary topography. This study also demonstrates the importance of topography and muting surface waves in controlled-source full waveform inversion.
Full-wave Simulation of Doppler Reflectometry in the Presence of Turbulence
Energy Technology Data Exchange (ETDEWEB)
Lechte, C. [Institut fur Plasmaforschung, Universitat Stuttgart, Stuttgart (Germany)
2011-07-01
Doppler reflectometry is a microwave plasma diagnostic well suited for density fluctuation measurement. A meaningful interpretation of Doppler reflectometry measurements necessitates the analysis of the wave propagation in the plasma using simulations methods. While the beam path can usually be reconstructed with beam tracing methods, the modeling of the scattering process demands the use of wave simulation codes. Furthermore, in the presence of strong density fluctuations, the response from the plasma is dominated by dispersion and multiple scattering, and hence becomes non-linear. IPF-FD3D is the finite difference time domain code used to investigate the dependence of the scattering efficiency on the various plasma conditions. It uses the full set of Maxwell equations and the electron equation of motion in a cold plasma. First results in slab geometry indicate a strong dependence of the scattering efficiency on the density gradient, the incident angle, and the wave polarisation. Further complications arise with the introduction of broadband turbulent fluctuations, where additional knowledge of the radial spectrum is necessary to reconstruct the full fluctuation spectrum from Doppler reflectometry measurements. This paper presents the reconstruction of the turbulent fluctuation spectrum from simulated Doppler reflectometry measurements in slab geometry. Two cases of analytical turbulence in slab geometry are presented where the fluctuation wavenumber spectrum was recovered. It is planned to extend these investigations to X mode polarization and to supplement actual fusion experiments
Uses of the ICRF and implications for future VLBI
Ma, Chopo
2006-01-01
Since its inception on 1 Jan 1998, the fundamental ICRF has been set by the VLBI positions of 212 "defining" extragalactic radio sources. In all there are approx.3000 sources with usefully accurate (< few mas) positions consistent with the ICRF. The uses of the ICRF include fundamental astrometry, monitoring of Earth orientation, and spacecraft navigation. For fundamental astrometry, stability and accuracy are most important, and realizations at different frequencies must be in proper registration. However, there is no preferred frequency, and the GAIA mission has the potential for an optical ICRF with 500,000 objects at the 50 microarcsec level some time after the planned 2011 launch. The radio ICRF should be properly prepared for a transition to assure long term stability and consistency. Earth orientation monitoring requires objects attached to the solid Earth, and VLBI will continue to be the fundamental technique. For this purpose it is essential that the new VLBI stations contemplated in the VLBI20l0 report be capable of observing a sufficiently large and well-distributed set of stable sources, and identifying these sources is an on-going effort. Spacecraft navigation by differential VLBI is planned using the Ka-band telemetry signal, and work has begun towards an ICRF realization suitable for this purpose. The balancing of different needs related to the VLBI ICRF will be discussed.
Full-waveform inversion with reflected waves for 2D VTI media
Pattnaik, Sonali
2016-09-06
Full-waveform inversion in anisotropic media using reflected waves suffers from the strong non-linearity of the objective function and trade-offs between model parameters. Estimating long-wavelength model components by fixing parameter perturbations, referred to as reflection-waveform inversion (RWI), can mitigate nonlinearity-related inversion issues. Here, we extend RWI to acoustic VTI (transversely isotropic with a vertical symmetry axis) media. To minimize trade-offs between the model parameters, we employ a new hierarchical two-stage approach that operates with the P-wave normal-moveout velocity and anisotropy coefficents ζ and η. First, is estimated using a fixed perturbation in ζ, and then we invert for η by fixing the updated perturbation in . The proposed 2D algorithm is tested on a horizontally layered VTI model.
Shertzer, Janine; Temkin, A.
2003-01-01
As is well known, the full scattering amplitude can be expressed as an integral involving the complete scattering wave function. We have shown that the integral can be simplified and used in a practical way. Initial application to electron-hydrogen scattering without exchange was highly successful. The Schrodinger equation (SE), which can be reduced to a 2d partial differential equation (pde), was solved using the finite element method. We have now included exchange by solving the resultant SE, in the static exchange approximation, which is reducible to a pair of coupled pde's. The resultant scattering amplitudes, both singlet and triplet, calculated as a function of energy are in excellent agreement with converged partial wave results.
Calculation of the Full Scattering Amplitude without Partial Wave Decomposition II
Shertzer, J.; Temkin, A.
2003-01-01
As is well known, the full scattering amplitude can be expressed as an integral involving the complete scattering wave function. We have shown that the integral can be simplified and used in a practical way. Initial application to electron-hydrogen scattering without exchange was highly successful. The Schrodinger equation (SE) can be reduced to a 2d partial differential equation (pde), and was solved using the finite element method. We have now included exchange by solving the resultant SE, in the static exchange approximation. The resultant equation can be reduced to a pair of coupled pde's, to which the finite element method can still be applied. The resultant scattering amplitudes, both singlet and triplet, as a function of angle can be calculated for various energies. The results are in excellent agreement with converged partial wave results.
Two-dimensional full-wave code for reflectometry simulations in TJ-II
International Nuclear Information System (INIS)
Blanco, E.; Heuraux, S.; Estrada, T.; Sanchez, J.; Cupido, L.
2004-01-01
A two-dimensional full-wave code in the extraordinary mode has been developed to simulate reflectometry in TJ-II. The code allows us to study the measurement capabilities of the future correlation reflectometer that is being installed in TJ-II. The code uses the finite-difference-time-domain technique to solve Maxwell's equations in the presence of density fluctuations. Boundary conditions are implemented by a perfectly matched layer to simulate free propagation. To assure the stability of the code, the current equations are solved by a fourth-order Runge-Kutta method. Density fluctuation parameters such as fluctuation level, wave numbers, and correlation lengths are extrapolated from those measured at the plasma edge using Langmuir probes. In addition, realistic plasma shape, density profile, magnetic configuration, and experimental setup of TJ-II are included to determine the plasma regimes in which accurate information may be obtained
Full-wave modeling of the O-X mode conversion in the Pegasus toroidal experiment
Energy Technology Data Exchange (ETDEWEB)
Koehn, A. [Institut fuer Plasmaforschung, Universitaet Stuttgart, D-70569 (Germany); Jacquot, J. [IRFM, CEA, F-13108 Saint-Paul-lez-Durance (France); Bongard, M. W.; Hinson, E. T.; Volpe, F. A. [Department of Engineering Physics, University of Wisconsin-Madison, Madison, Wisconsin 53706 (United States); Gallian, S. [Department of Electrical and Computer Engineering, University of Wisconsin-Madison, Madison, Wisconsin 53706 (United States)
2011-08-15
The ordinary-extraordinary (O-X) mode conversion is modeled with the aid of a 2D full-wave code in the Pegasus toroidal experiment as a function of the launch angles. It is shown how the shape of the plasma density profile in front of the antenna can significantly influence the mode conversion efficiency and, thus, the generation of electron Bernstein waves (EBWs). It is therefore desirable to control the density profile in front of the antenna for successful operation of an EBW heating and current drive system. On the other hand, the conversion efficiency is shown to be resilient to vertical displacements of the plasma as large as {+-}10 cm.
ICRF-induced fusion product loss in TFTR
International Nuclear Information System (INIS)
Darrow, D.S.; Chang, C.S.; Zweben, S.J.
1994-01-01
When ICRF power is applied to plasmas in which there is no externally-supplied minority species, an enhanced loss of DD fusion products results. The characteristics of the loss are consistent with particles at or near the birth energy having their perpendicular velocity increased by the ICRF such that those near the passing/trapped boundary are carried into the first orbit loss cone. A rudimentary model of this process predicts losses of a magnitude similar to those seen. Predictions based upon this data for hypothetical ICRF ash removal from reactor plasmas suggest that the technique will not be energy efficient
A new radiation stripline ICRF antenna design for EAST Tokamak
International Nuclear Information System (INIS)
Qin, C. M.; Zhao, Y. P.; Wan, B. N.; Li, J.; Zhang, X. J.; Yang, Q. X.; Yuan, S.; Braun, F.; Notedame, J.-M.; Kasahara, H.
2014-01-01
A new type of toroidal long Radiation Stripline Antenna (RSA) is presented, which can effectively improve antenna radiation, leading in reduction of max voltage on transmission line and decrease of the sensitivity to ELM's of the ICRF system at some frequencies. Based on the new concept, a 4-straps RSA is proposed for EAST device. Using 3-D computing simulator code (HFSS), RF current distribution, S-parameters and electromagnetic field distribution on and near the RSA ICRF antenna are analyzed and compared with present ICRF antenna on EAST
ICRF-induced DD fusion product losses in TFTR
International Nuclear Information System (INIS)
Darrow, D.S.; Zweben, S.J.; Budny, R.V.
1994-10-01
When ICRF power is applied to TFTR plasmas in which there is no externally-supplied minority species, an enhanced loss of DD fusion products results. The characteristics of the loss are consistent with particles at or near the birth energy having their perpendicular velocity increased by the ICRF such that those near the passing/trapped boundary are carried into the first orbit loss cone. A rudimentary model of this process predicts losses of a magnitude similar to those seen. Extrapolations based upon this data for hypothetical ICRF ash removal from reactor plasmas suggest that the technique will not be energy efficient
Directory of Open Access Journals (Sweden)
Koichi Narahara
2012-01-01
Full Text Available Nonlinear transmission lines, which define transmission lines periodically loaded with nonlinear devices such as varactors, diodes, and transistors, are modeled in the framework of finite-difference time-domain (FDTD method. Originally, some root-finding routine is needed to evaluate the contributions of nonlinear device currents appropriately to the temporally advanced electrical fields. Arbitrary nonlinear transmission lines contain large amount of nonlinear devices; therefore, it costs too much time to complete calculations. To reduce the calculation time, we recently developed a simple model of diodes to eliminate root-finding routines in an FDTD solver. Approximating the diode current-voltage relation by a piecewise-linear function, an extended Ampere's law is solved in a closed form for the time-advanced electrical fields. In this paper, we newly develop an FDTD model of field-effect transistors (FETs, together with several numerical examples that demonstrate pulse-shortening phenomena in a traveling-wave FET.
Heating profiles on ICRF antenna Faraday shields
International Nuclear Information System (INIS)
Taylor, D.J.; Baity, F.W.; Hahs, C.L. Riemer, B.W.; Ryan, D.M.; Williamson, D.E.
1992-01-01
Poor definition of the heating profiles that occur during normal operation of Faraday shields for ion cyclotron resonant frequency (ICRF) antennas has complicated the mechanical design of ICRF system components. This paper reports that at Oak Ridge National Laboratory (ORNL), Faraday shield analysis is being used in defining rf heating profiles. In recent numerical analyses of proposed hardware for the Burning Plasma Experiment (BPX) and DIII-D, rf magnetic fields at Faraday shield surfaces were calculated, providing realistic predictions of the induced skin currents flowing on the shield elements and the resulting dissipated power profile. Detailed measurements on mock-ups of the Faraday shields for DIII-D and the Tokamak Fusion Test Reactor (TFTR) confirmed the predicted magnetic field distributions. A conceptual design for an uncooled Faraday shield for the BPX ion cyclotron resonance heating (ICRH) antenna, which should withstand the proposed long-pulse operation, has been completed. The analytical effort is described in detail, with emphasis on the design work for the BPX ICRH antenna conceptual design and for the replacement Faraday shield for the DIII-D FWCD antenna. Results of analyses are shown, and configuration issues involved in component modeling are discussed
Full polarimetric millimetre wave radar for stand-off security screening
Blackhurst, Eddie; Salmon, Neil; Southgate, Matthew
2017-10-01
The development and measurements are described of a frequency modulated continuous wave (FMCW) mono-static millimetre wave full polarimetric radar, operating at k-band (18 to 26 GHz). The system has been designed to explore the feasibility of using full polarimetry for the detection of concealed weapons, and person borne improvised explosive devices (PBIED). The philosophy of this scheme is a means to extract the maximum information content from a target which is normally in the single spatial pixel (sometimes sub-pixel) configuration in stand-off (tens of metres) and crowd surveillance scenarios. The radar comprises a vector network analyser (VNA), an orthomode transducer and a conical horn antenna. A calibration strategy is discussed and demonstrated using a variety of known calibration targets with known reflective properties, including a flat metal plate, dihedral reflector, metal sphere, helix and dipole. The orthomode transducer is based on a high performance linear polarizer of the turnstile type with isolation better than - 35dB between orthogonal polarisations. The calibration enables the polarimetric Sinclair scattering matrix to be measured at each frequency for coherent polarimetry, and this can be extended using multiple measurements via the Kennaugh matrix to investigate incoherent full polarimetry.
Ernst, D. R.; Rhodes, T. L.; Kubota, S.; Crocker, N.
2017-10-01
Plasma full-wave simulations of the DIII-D DBS system including its lenses and mirrors are developed using the GPU-based FDTD2D code, verified against the GENRAY ray-tracing code and TORBEAM paraxial beam code. Our semi-analytic description of the effective spot size for a synthetic diagnostic reveals new focusing and defocusing effects arising from the combined effects of the curvature of the reflecting surface and that of the Gaussian beam wavefront. We compute the DBS transfer function from full-wave simulations to verify these effects. Using the synthetic diagnostic, nonlinear GYRO simulations closely match DBS fluctuation spectra with and without strong electron heating, without adjustment or change in normalization, while both GYRO and GENE also match fluxes in all transport channels. Density gradient driven TEMs that are observed by the DBS diagnostic on DIII-D are reproduced by simulations as a band of discrete toroidal mode numbers which intensify during strong electron heating. Work supported by US DOE under DE-FC02-04ER54698 and DE-FG02-08ER54984.
ICRF sawtooth stabilization: Application on TFTR and CIT
International Nuclear Information System (INIS)
Hosea, J.C.; Phillips, C.K.; Stevens, J.E.; Wilson, J.R.; Bell, M.; Boivin, R.; Cavallo, A.; Colestock, P.; Fredrickson, E.; Hammett, G.; Hsuan, H.; Janos, A.; Jassby, D.; Jobes, F.; McGuire, K.; Mueller, D.; Nagayama, Y.; Owens, K.; Park, H.; Schmidt, G.; Stratton, B.; Taylor, G.; Wong, K.L.; Zweben, S.
1991-03-01
The use of ICRF heating to stabilize the core plasma sawtooth relaxations has been extended to TFTR where such stabilization has been produced at relatively low power in the L Mode regime at moderate density (P RF = 4 MW, 2.6 MW in helium and deuterium discharges, respectively, for the minority hydrogen ICRF heating regime with bar n e ∼2.5 x 10 13 cm -3 ). These results, as in the case of those obtained on JET, are qualitatively consistent with energetic ion stabilization of the m = 1, n = 1 ideal/resistive kink mode. The relevance of sawtooth stabilization to the primary regimes of interest on TFTR -- the high-Q supershot regime and the high density pellet injection regimes -- and on CIT -- the high density ICRF heated regime -- is considered in the context of the present theory and the projected ICRF power deposition characteristics. 35 refs., 11 figs
Development of a fishbone travelling wave antenna for LHD
International Nuclear Information System (INIS)
Takase, Y.; Ejiri, A.; Shiraiwa, S.
2002-10-01
A travelling wave antenna in the ion cyclotron range of frequencies (ICRF) is being developed for LHD, motivated by the need to provide a capability for rotational transform profile control by noninductively driven current. Stability calculations suggest that it is possible to increase the beta limit and obtain access to the second stability regime by controlling the rotational transform profile. Current drive by the ICRF fast wave (magnetosonic wave) can be used for such a purpose. (author)
International Nuclear Information System (INIS)
Thompson, K.; Martinez, T.J.
1999-01-01
We present a new approach to first-principles molecular dynamics that combines a general and flexible interpolation method with ab initio evaluation of the potential energy surface. This hybrid approach extends significantly the domain of applicability of ab initio molecular dynamics. Use of interpolation significantly reduces the computational effort associated with the dynamics over most of the time scale of interest, while regions where potential energy surfaces are difficult to interpolate, for example near conical intersections, are treated by direct solution of the electronic Schroedinger equation during the dynamics. We demonstrate the concept through application to the nonadiabatic dynamics of collisional electronic quenching of Li(2p). Full configuration interaction is used to describe the wave functions of the ground and excited electronic states. The hybrid approach agrees well with full ab initio multiple spawning dynamics, while being more than an order of magnitude faster. copyright 1999 American Institute of Physics
Orbit losses of strongly ICRF-heated ions
International Nuclear Information System (INIS)
Anderson, A.; Dillner, Oe.; Lisak, M.
1992-01-01
An approximate analytical investigation is made to assess the importance of orbit losses of strongly ICRF-heated minority ions. Explicit expressions for the fraction of lost minority ions are derived and shown to be in good agreement with numerical simulation results. The results indicate that present day ICRF heating power density levels cannot be raised significantly without causing important particle and energy losses due to unconfined particle orbits. 6 refs., 5 figs
Design and control of phased ICRF antenna arrays
International Nuclear Information System (INIS)
Goulding, R.H.; Baity, F.W.; Hoffman, D.J.
1993-01-01
Phased antenna arrays operating in the ion cyclotron range of frequencies (ICRF) are used to produce highly directional wave spectra, primarily for use in current drive experiments. RF current drive using phased antennas has been demonstrated in both the JET and DIII-D tokamaks, and both devices are planning to operate new four-element arrays beginning early next year. Features of antenna design that are relevant to phased operation and production of directional spectra are reviewed. Recent advances in the design of the feed circuits and the related control systems for these arrays should substantially improve their performance, by reducing the coupling seen by the matching networks and rf power supplies caused by the mutual impedance of the array elements. The feed circuit designs for the DIII-D and JET phased antenna arrays are compared. The two configurations differ significantly due to the fact that one power amplifier is used for the entire array in the former case, and one per element in the latter. The JET system uses automatic feedback control of matching, phase and amplitude of antenna currents, and the transmitter power balance. The design of this system is discussed, and a time dependent model used to predict its behavior is described
ICRF [Ion Cyclotron Range of Frequencies] edge modeling studies
International Nuclear Information System (INIS)
Lehrman, I.S.; Colestock, P.L.
1989-01-01
Theoretical models have been developed, and are currently being refined, to explain the edge plasma-antenna interaction that occurs during ICRF heating. The periodic structure of a Faraday shielded antenna is found to result in strong ponderomotive force in the vicinity of the antenna. A fluid model, which incorporates the ponderomotive force, shows an increase in transport to the Faraday shield. A kinetic model shows that the strong antenna near fields act to increase the energy of deuterons which strike the shield, thereby increasing the sputtering of shield material. Estimates of edge impurity harmonic heating no significant heating for either in or out-of-phase antenna operation. Additionally, a particle model for electrons near the shield shows that heating results from the parallel electric field associated with the fast wave. A quasilinear model for edge electron heating is presented and compared to the particle calculations. The models' predictions are shown to be consistent with measurements of enhanced transport. 19 refs., 9 figs
ICRF Mode Conversion Current Drive for Plasma Stability Control in Tokamaks
International Nuclear Information System (INIS)
Grekov, D.; Kock, R.; Lyssoivan, A.; Noterdaeme, J. M.; Ongena, J.
2007-01-01
There is a substantial incentive for the International Thermonuclear Experimental Reactor (ITER) to operate at the highest attainable beta (plasma pressure normalized to magnetic pressure), a point emphasized by requirements of attractive economics in a reactor. Recent experiments aiming at stationary high beta discharges in tokamak plasmas have shown that maximum achievable beta value is often limited by the onset of instabilities at rational magnetic surfaces (neoclassical tearing modes). So, methods of effective control of these instabilities have to be developed. One possible way for neoclassical tearing modes control is an external current drive in the island to locally replace the missing bootstrap current and thus to suppress the instability. Also, a significant control of the sawtooth behaviour was demonstrated when the magnetic shear was modified by driven current at the magnetic surface where safety factor equals to 1. In the ion cyclotron range of frequencies (ICRF), the mode conversion regime can be used to drive the local external current near the position of the fast-to-slow wave conversion layer, thus providing an efficient means of plasma stability control. The slow wave energy is effectively absorbed in the vicinity of mode conversion layer by electrons with such parallel to confining magnetic field velocities that the Landau resonance condition is satisfied. For parameters of present day tokamaks and for ITER parameters the slow wave phase velocity is rather low, so the large ratio of momentum to energy content would yield high current drive efficiency. In order to achieve noticeable current drive effect, it is necessary to create asymmetry in the ICRF power absorption between top and bottom parts of the plasma minor cross-section. Such asymmetric electron heating may be realized using: - shifted from the torus midplane ICRF antenna in TEXTOR tokamak; - plasma displacement in vertical direction that is feasible in ASDEX-Upgrade; - the
Grigoriev, S. V.; Sukhanov, A. S.; Altynbaev, E. V.; Siegfried, S.-A.; Heinemann, A.; Kizhe, P.; Maleyev, S. V.
2015-12-01
We develop the technique to study the spin-wave dynamics of the full-polarized state of the Dzyaloshinskii-Moriya helimagnets by polarized small-angle neutron scattering. We have experimentally proven that the spin-waves dispersion in this state has the anisotropic form. We show that the neutron scattering image displays a circle with a certain radius which is centered at the momentum transfer corresponding to the helix wave vector in helimagnetic phase ks, which is oriented along the applied magnetic field H . The radius of this circle is directly related to the spin-wave stiffness of this system. This scattering depends on the neutron polarization showing the one-handed nature of the spin waves in Dzyaloshinskii-Moriya helimagnets in the full-polarized phase. We show that the spin-wave stiffness A for MnSi helimagnet decreased twice as the temperature increases from zero to the critical temperature Tc.
Ellsworth, W. L.; Karrenbach, M. H.; Zumberge, M. A.
2017-12-01
The main borehole at the San Andreas Fault Observatory at Depth (SAFOD) contains optical fibers cemented in place in between casing strings from the surface to just below the top of the basement. The fibers are under tension of approximately 1 N and are housed in a 0.9 mm diameter stainless steel tube. Earth strain is transmitted to the fiber by frictional contact with the tube wall. One fiber has been in use as a vertical strainmeter since 2005, measuring the total strain between 9 and 740 m by laser interferometry. In June 2017 we attached an OptaSense Distributed Acoustic Sensing (DAS) system, model ODH3.1, to a second fiber that terminates at 864 m depth. The DAS laser interrogator measures the strain over a gauge length with a set spacing between gauge intervals. For this experiment we set the gauge length to 10 m with 1 m spacing between gauges. Including the surface run of the fiber, this gives us 936 channels measuring the vertical strain at a sample interval of 0.4 msec (2500 samples/s). Continuous recording of the string produces approximately 1 TB/day. During one month of data collection, we recorded local, regional and teleseismic earthquakes. With this recording geometry, the DAS system captures the full vertical wavefield between the basement interface and free surface, revealing direct, converted and refracted waves. Both P- and S- strain waves are clearly visible in the data, even for 10 km deep earthquakes located almost directly below the well (see figure). The incident and surface reflected wavefields can be separated by frequency-wavenumber filtering due to the large-aperture and fine spatial and temporal sampling. Up- and downgoing strain waves illuminate the subsurface within the sensor array's depth range. Accurate arrival time determinations of the initial arrival phase are possible due to consistent wave forms recorded at 1 m spatial intervals that can be used for fine-scale shallow velocity model estimation.
International Nuclear Information System (INIS)
Gambier, D.J.
1983-06-01
Experiments on plasma heating by RF in the ion cyclotron range of frequency have been performed on T.F.R. in various regimes, such as the mode conversion regime and the minority regime. The latest theoretical developments of ICRF modeling are presented and the experimental data obtained in a deuterium plasma containing 20% or 5% of hydrogen are reviewed. With 20% of hydrogen a large increase of both ion and electron temperature is observed while the level of metallic impurity radiation has been considerably reduced using a carbon limiter. With 5% of hydrogen the location of the antenna system in the minor cross section produces no dramatic differences with respect to ion heating. Finally the metallic impurity production is examined and thus allows one to eliminate the Faraday shield of the antenna as the main source of pollution by heavy ions of the plasma
Advanced fusion in ICRF injected plasmas
International Nuclear Information System (INIS)
Carpignano, F.; Coppi, B.; Detragiache, P.; Migliuolo, S.; Nassi, M.; Rogers, B.
1994-01-01
Fusion burning of a D- 3 He mixture in a high density, high magnetic field, compact toroidal experiment (Ignitor) with a high injected power density at the ion cyclotron frequency (ICRF) is investigated. A superthermal tail (with energies exceeding 1 MeV in the central part of the plasma column) is induced in the distribution of the minority 3 He population ( 0 20 m -3 ). This stems from the high value of the peak RF power density absorbed by the minority species (ρ RF ∼ 60 MW/m 3 ) that should be obtained in Ignitor when the total injected power is about 18 MW. This experiment is suitable to begin the study of advanced fusion burning, because of the high plasma currents (I p 3 He fusion powers of the order of 1 MW should be attained. (author) 8 refs., 3 figs
EMC3-Eirene simulations of gas puff effects on edge density and ICRF coupling in ASDEX Upgrade
Energy Technology Data Exchange (ETDEWEB)
Zhang, Wei; Noterdaeme, Jean-Marie [Max Planck Institute for Plasma Physics, Garching (Germany); University of Ghent, Ghent (Belgium); Coster, David; Lunt, Tilmann; Bobkov, Volodymyr; Feng, Yuehe [Max Planck Institute for Plasma Physics, Garching (Germany); Collaboration: ASDEX Upgrade team
2015-05-01
Ion cyclotron range of frequency (ICRF) heating relies on the Fast Wave (FW) to transport the power from the edge (the antenna) to the plasma center. Since the FW is evanescent below a critical density (typically in the 10{sup 18} m{sup -3} range), the wave does not propagate in the region where the density is below this value in the very edge of the plasma. The coupling depends strongly on the width of this region. The distance between the ICRF antenna and the FW cut-off layer can be made smaller by increasing the edge density in front of the ICRF antenna. Previous experiments in many tokamaks and preliminary simulation results for AUG and JET with EDGE2D-EIRENE show that the edge density could indeed be increased with gas puffing at the top of the vessel or in the midplane. But the 2D code cannot quantitatively reproduce the experimental results, mainly due to the assumptions of toroidal axisymmetry. EMC3-EIRENE is a 3D Edge Monte Carlo plasma fluid transport code. By including the toroidal nonaxisymmetric plasma facing components and 3D positions of gas valves in the code, the simulations can be made more realistic. We will show first simulation results of the code and a comparison to experiments.
International Nuclear Information System (INIS)
Smithe, D.N.; Colestock, P.L.; Kashuba, R.J.; Kammash, T.
1987-04-01
A computational scheme is developed which permits tractable calculation of three-dimensional full-wave solutions to the Maxwell-Vlasov equations under typical Ion Cyclotron Range of Frequencies (ICRF) experimental conditions. The method is unique in that power deposition to the plasma is determined via the anti-Hermitian part of a truncated warm-plasma dielectric operator, rather than as the result of an assumed phenomenological collision frequency. The resulting computer code allows arbitrary variation of density, temperature, magnetic field, and minority concentration in the poloidal plane by performing a convolution of poloidal modes to produce a coupled system of differential equations in the radial variable. By assuming no inhomogeneity along the toroidal axis, an inverse transform over k/sub parallel/ is performed to yield the full three-dimensional field solutions. The application of the code to TFTR-like plasmas shows a mild resonance structure in antenna loading related to the changing number of wavelengths between antenna and the resonance layer. 48 figs
Parisi, Laura; Ferreira, Ana M.G.
2016-01-01
The surface wave full ray theory (FRT) is an efficient tool to calculate synthetic waveforms of surface waves. It combines the concept of local modes with exact ray tracing as a function of frequency, providing a more complete description of surface
Directory of Open Access Journals (Sweden)
Mehdi Raoofian Naeeni
2016-12-01
Full Text Available The problem of propagation of plane wave including body and surface waves propagating in a transversely isotropic half-space with a depth-wise axis of material symmetry is investigated in details. Using the advantage of representation of displacement fields in terms of two complete scalar potential functions, the coupled equations of motion are uncoupled and reduced to two independent equations for potential functions. In this paper, the secular equations for determination of body and surface wave velocities are derived in terms of both elasticity coefficients and the direction of propagation. In particular, the longitudinal, transverse and Rayleigh wave velocities are determined in explicit forms. It is also shown that in transversely isotropic materials, a Rayleigh wave may propagate in different manner from that of isotropic materials. Some numerical results for synthetic transversely isotropic materials are also illustrated to show the behavior of wave motion due to anisotropic nature of the problem.
A PIC-MCC code RFdinity1d for simulation of discharge initiation by ICRF antenna
Tripský, M.; Wauters, T.; Lyssoivan, A.; Bobkov, V.; Schneider, P. A.; Stepanov, I.; Douai, D.; Van Eester, D.; Noterdaeme, J.-M.; Van Schoor, M.; ASDEX Upgrade Team; EUROfusion MST1 Team
2017-12-01
Discharges produced and sustained by ion cyclotron range of frequency (ICRF) waves in absence of plasma current will be used on ITER for (ion cyclotron-) wall conditioning (ICWC, Te = 3{-}5 eV, ne 18 m-3 ). In this paper, we present the 1D particle-in-cell Monte Carlo collision (PIC-MCC) RFdinity1d for the study the breakdown phase of ICRF discharges, and its dependency on the RF discharge parameters (i) antenna input power P i , (ii) RF frequency f, (iii) shape of the electric field and (iv) the neutral gas pressure pH_2 . The code traces the motion of both electrons and ions in a narrow bundle of magnetic field lines close to the antenna straps. The charged particles are accelerated in the parallel direction with respect to the magnetic field B T by two electric fields: (i) the vacuum RF field of the ICRF antenna E_z^RF and (ii) the electrostatic field E_zP determined by the solution of Poisson’s equation. The electron density evolution in simulations follows exponential increase, {\\dot{n_e} ∼ ν_ion t } . The ionization rate varies with increasing electron density as different mechanisms become important. The charged particles are affected solely by the antenna RF field E_z^RF at low electron density ({ne < 1011} m-3 , {≤ft \\vert E_z^RF \\right \\vert \\gg ≤ft \\vert E_zP \\right \\vert } ). At higher densities, when the electrostatic field E_zP is comparable to the antenna RF field E_z^RF , the ionization frequency reaches the maximum. Plasma oscillations propagating toroidally away from the antenna are observed. The simulated energy distributions of ions and electrons at {ne ∼ 1015} m-3 correspond a power-law Kappa energy distribution. This energy distribution was also observed in NPA measurements at ASDEX Upgrade in ICWC experiments.
Pan, Yudi; Gao, Lingli; Bohlen, Thomas
2018-05-01
Correct estimation of near-surface seismic-wave velocity when encountering lateral heterogeneity and free surface topography is one of the challenges to current shallow seismic. We propose to use time-domain full-waveform inversion (FWI) of surface waves, including both Rayleigh and Love waves, to solve this problem. We adopt a 2D time-domain finite-difference method with an improved vacuum formulation (IVF) to simulate shallow-seismic Rayleigh wave in presence of free-surface topography. We modify the IVF for SH-wave equation for the simulation of Love wave in presence of topographic free surface and prove its accuracy by benchmark tests. Checkboard model tests are performed in both cases when free-surface topography is included or neglected in FWI. Synthetic model containing a dipping planar free surface and lateral heterogeneity was then tested, in both cases of considering and neglecting free-surface topography. Both checkerboard and synthetic models show that Rayleigh- and Love-wave FWI have similar ability of reconstructing near-surface structures when free-surface topography is considered, while Love-wave FWI could reconstruct near-surface structures better than Rayleigh-wave when free-surface topography is neglected.
Reflection and transmission of full-vector X-waves normally incident on dielectric half spaces
Salem, Mohamed; Bagci, Hakan
2011-01-01
polarization components, which are derived from the scalar X-Wave solution. The analysis of transmission and reflection is carried out via a straightforward but yet effective method: First, the X-Wave is decomposed into vector Bessel beams via the Bessel-Fourier
International Nuclear Information System (INIS)
Shibata, Masaru; Sekiguchi, Yu-ichirou
2004-01-01
Axisymmetric numerical simulations of rotating stellar core collapse to a neutron star are performed in the framework of full general relativity. The so-called Cartoon method, in which the Einstein field equations are solved in Cartesian coordinates and the axisymmetric condition is imposed around the y=0 plane, is adopted. The hydrodynamic equations are solved in cylindrical coordinates (on the y=0 plane in Cartesian coordinates) using a high-resolution shock-capturing scheme with maximum grid size (2500,2500). A parametric equation of state is adopted to model collapsing stellar cores and neutron stars following Dimmelmeier, Font, and Mueller. It is found that the evolution of the central density during the collapse, bounce, and formation of protoneutron stars agrees well with that in the work of Dimmelmeier, Font, and Mueller in which an approximate general relativistic formulation is adopted. This indicates that such an approximation is appropriate for following axisymmetric stellar core collapses and the subsequent formation of protoneutron stars. Gravitational waves are computed using a quadrupole formula. It is found that the waveforms are qualitatively in good agreement with those by Dimmelmeier, Font, and Mueller. However, quantitatively, two waveforms do not agree well. The possible reasons for the disagreement are discussed
Characterization of an SRF gun: a 3D full wave simulation
International Nuclear Information System (INIS)
Wang, E.; Ben-Zvi, I.; Wang, J.
2011-01-01
We characterized a BNL 1.3GHz half-cell SRF gun is tested for GaAs photocathode. The gun already was simulated several years ago via two-dimensional (2D) numerical codes (i.e., Superfish and Parmela) with and without the beam. In this paper, we discuss our investigation of its characteristics using a three dimensional (3D) full-wave code (CST STUDIO SUITE(trademark)).The input/pickup couplers are sited symmetrically on the same side of the gun at an angle of 180 o . In particular, the inner conductor of the pickup coupler is considerably shorter than that of the input coupler. We evaluated the cross-talk between the beam (trajectory) and the signal on the input coupler compared our findings with published results based on analytical models. The CST STUDIO SUITE(trademark) also was used to predict the field within the cavity; particularly, a combination of transient/eigenmode solvers was employed to accurately construct the RF field for the particles, which also includes the effects of the couplers. Finally, we explored the beam's dynamics with a particle in cell (PIC) simulation, validated the results and compare them with 2D code result.
Variational full wave calculation of fast wave current drive in DIII-D using the ALCYON code
International Nuclear Information System (INIS)
Becoulet, A.; Moreau, D.
1992-04-01
Initial fast wave current drive simulations performed with the ALCYON code for the 60 MHz DIII-D experiment are presented. Two typical shots of the 1991 summer campaign were selected with magnetic field intensities of 1 and 2 teslas respectively. The results for the wave electromagnetic field in the plasma chamber are displayed. They exhibit a strong enrichment of the poloidal mode number m-spectrum which leads to the upshift of the parallel wavenumber, κ perpendicular, and to the wave absorption. The m-spectrum is bounded when the local poloidal wavenumber reaches the Alfven wavenumber and the κ perpendicular upshifts do not destroy the wave directionality. Linear estimations of the driven current are made. The current density profiles are found to be peaked and we find that about 88 kA can be driven in the 1 tesla/1.7 keV phase with 1.7 MW coupled to the electrons. In the 2 tesla/3.4 keV case, 47 kA are driven with a total power of 1.5 MW, 44% of which are absorbed on the hydrogen minority, through the second harmonic ion cyclotron resonance. The global efficiency is then 0.18 x 10 19 A m -2 W -1 if one considers only the effective power going to the electrons
Development of impedance matching technologies for ICRF antenna arrays
International Nuclear Information System (INIS)
Pinsker, R.I.
1998-01-01
All high-power ion cyclotron range of frequency (ICRF) heating systems include devices for matching the input impedance of the antenna array to the generator output impedance. For most types of antennas used, the input impedance is strongly time dependent on timescales as rapid as 10 -1 s, while the radio frequency (RF) generators used are capable of producing full power only into a stationary load impedance. Hence, the dynamic response of the matching method is of great practical importance. In this paper, world-wide developments in this field over the past decade are reviewed. These techniques may be divided into several classes. The edge plasma parameters that determine the antenna array's input impedance may be controlled to maintain a fixed load impedance. The frequency of the RF source can be feedback controlled to compensate for changes in the edge plasma conditions, or fast variable tuning elements in the transmission line between the generator output and the antenna input connections can provide the necessary time-varying impedance transformation. In 'lossy passive schemes', reflected power due to the time-varying impedance of the antenna array is diverted to a dummy load. Each of these techniques can be applied to a pre-existing antenna system. If a new antenna is to be designed, recent advances allow the antenna array to have the intrinsic property of presenting a constant load to the feeding transmission lines despite the varying load seen by each antenna in the array. (author)
Development of impedance matching technologies for ICRF antenna arrays
International Nuclear Information System (INIS)
Pinsker, R.I.
1998-03-01
All high power ICRF heating systems include devices for matching the input impedance of the antenna array to the generator output impedance. For most types of antennas used, the input impedance is strongly time-dependent on timescales as rapid as 10-4 s, while the rf generators used are capable of producing full power only into a stationary load impedance. Hence, the dynamic response of the matching method is of great practical importance. In this paper, world-wide developments in this field over the past decade are reviewed. These techniques may be divided into several classes. The edge plasma parameters that determine the antenna array's input impedance may be controlled to maintain a fixed load impedance. The frequency of the rf source can be feedback controlled to compensate for changes in the edge plasma conditions, or fast variable tuning elements in the transmission line between the generator output and the antenna input connections can provide the necessary time-varying impedance transformation. In lossy passive schemes, reflected power due to the time-varying impedance of the antenna array is diverted to a dummy load. Each of these techniques can be applied to a pre-existing antenna system. If a new antenna is to be designed, recent advances allow the antenna array to have the intrinsic property of presenting a constant load to the feeding transmission lines despite the varying load seen by each antenna in the array
High-power ICRF and ICRF plus neutral-beam heating on PLT
International Nuclear Information System (INIS)
Hwang, D.; Bitter, M.; Budny, R.
1983-01-01
PLT ICRF experiments with RF powers up to approx.=3 MW have demonstrated efficient plasma heating in both the minority fundamental and the second harmonic ion-cyclotron regimes. In the minority 3 He regime, ion temperatures of approx.=3 keV have been produced along with approx.=1 kW of D- 3 He fusion power and substantial electron heating. In the second harmonic H regime, an equivalent averaged ion energy of approx.=4 keV has been achieved. Combined ICRF plus neutral-beam heating experiments with auxiliary powers totalling up to 4.5 MW have provided insight into auxiliary heating performance at stored plasma energy levels up to approx.=100 kJ. Values of #betta#sub(phi) in the range of 1.5-2% have been attained for Bsub(phi) approx.=17 kG. Energetic discharges with n-barsub(e) up to approx.6x10 13 cm - 3 at Bsub(phi) approx.=28 kG have also been investigated. Preliminary confinement studies suggest that energetic ion losses may contribute to a direct loss of the input RF power in the H minority heating regime but are insignificant in the 3 He minority case. The energy confinement time for the H minority regime is reduced somewhat from the Ohmic value. (author)
ICRF power limitation relation to density limit in ASDEX
International Nuclear Information System (INIS)
Ryter, F.
1992-01-01
Launching high ICRF power into ASDEX plasmas required good antenna-plasma coupling. This could be achieved by sufficient electron density in front of the antennas i.e. small antenna-plasma distance (1-2 cm) and moderate to high line-averaged electron density compared to the density window in ASDEX. These are conditions eventually close to the density limit. ICRF heated discharges terminated by plasma disruptions caused by the RF pulse limited the maximum RF power which can be injected into the plasma. The disruptions occurring in these cases have clear phenomenological similarities with those observed in density limit discharges. We show in this paper that the ICRF-power limitation by plasma disruptions in ASDEX was due to reaching the density limit. (orig.)
DT simulation of ICRF heated supershots in TFTR using TRANSP
International Nuclear Information System (INIS)
Goldfinger, R.C.; Batchelor, D.B.; Phillips, C.K.; Budny, R.; Hammett, G.W.; Hosea, J.C.; McCune, D.M.; Stevens, J.E.; Wilson, J.R.
1993-01-01
The principal goal of ion cyclotron range of frequency (ICRF) heating on the Tokamak Fusion Test Reactor (TFTR) is to enhance plasma performance during the deuterium-tritium (DT) physics phase of operations. Strongly centralized ICRF heating may play a critical role in obtaining high Q DT and high β α operation in TFTR, as well as in future fusion reactors. ICRF heating of a dilute minority species leads to the formation of an energetic ion population that, in turn, provides strong central electron heating. The corresponding rise in the central electron temperature translates into an increase in the slowing-down time of either neutral beam or alpha particles in the discharge. Preliminary DT simulations of the experimental results in deuterium-deuterium (DD) plasmas performed with the TRANSP code are presented in this paper
ICRF power limitation relation to density limit in ASDEX
International Nuclear Information System (INIS)
Ryter, F.
1992-01-01
Launching high ICRF power into ASDEX plasmas required good antenna-plasma coupling. This could be achieved by sufficient electron density in front of the antennas i.e. small antenna-plasma distance (1-2 cm) and moderate to high line-averaged electron density compared to the density window in ASDEX. These are conditions eventually close to the density limit. ICRF heated discharges terminated by plasma disruptions caused by the RF pulse limited the maximum RF power which can be injected into the plasma. The disruptions occurring in these cases have clear phenomenological similarities with those observed in density limit discharges. We show in this paper that the ICRF-power limitation by plasma disruptions in ASDEX was due to reaching the density limit. (author) 3 refs., 3 figs
On the tunneling of full-vector X-Waves through a slab under frustrated total reflection condition
Salem, Mohamed; Bagci, Hakan
2012-01-01
Tunneling of full-vector X-Waves through a dielectric slab under frustrated total reflection condition is investigated. Full-vector X-Waves are obtained by superimposing transverse electric and magnetic polarization components, which are derived from the scalar X-Wave solution. The analysis of reflection and transmission at the dielectric interfaces is carried out analytically in a straightforward fashion using vector Bessel beam expansion. Investigation of the fields propagating away from the farther end of the slab (transmitted fields) shows an advanced (superluminal) transmission of the X-Wave peak. Additionally, a similar advanced reflection is also observed. The apparent tunneling of the peak is shown to be due to the phase shift in the fields' spectra and not to be causally related to the incident peak. © 2012 IEEE.
On the tunneling of full-vector X-Waves through a slab under frustrated total reflection condition
Salem, Mohamed
2012-07-01
Tunneling of full-vector X-Waves through a dielectric slab under frustrated total reflection condition is investigated. Full-vector X-Waves are obtained by superimposing transverse electric and magnetic polarization components, which are derived from the scalar X-Wave solution. The analysis of reflection and transmission at the dielectric interfaces is carried out analytically in a straightforward fashion using vector Bessel beam expansion. Investigation of the fields propagating away from the farther end of the slab (transmitted fields) shows an advanced (superluminal) transmission of the X-Wave peak. Additionally, a similar advanced reflection is also observed. The apparent tunneling of the peak is shown to be due to the phase shift in the fields\\' spectra and not to be causally related to the incident peak. © 2012 IEEE.
Wang, Ximei; Zhu, Liqun; Li, Weiping; Liu, Huicong; Li, Yihong
2009-03-01
Anodic films have been prepared on the AZ91D magnesium alloys in 1 mol/L Na 2SiO 3 with 10 vol.% silica sol addition under the constant voltage of 60 V at room temperature by half-wave and full-wave power sources. The weight of the anodic films has been scaled by analytical balance, and the thickness has been measured by eddy current instrument. The surface morphologies, chemical composition and structure of the anodic films have been characterized by scanning electron microscopy (SEM), energy dispersion spectrometry (EDS), X-ray diffraction (XRD) and transmission electron microscopy (TEM). The results show that the thickness and weight of the anodic films formed by the two power sources both increase with the anodizing time, and the films anodized by full-wave power source grow faster than that by half-wave one. Furthermore, we have fitted polynomial to the scattered data of the weight and thickness in a least-squares sense with MATLAB, which could express the growth process of the anodic films sufficiently. The full-wave power source is inclined to accelerate the growth of the anodic films, and the half-wave one is mainly contributed to the uniformity and fineness of the films. The anodic film consists of crystalline Mg 2SiO 4 and amorphous SiO 2.
Energy Technology Data Exchange (ETDEWEB)
Wang Ximei [Key Laboratory of Aerospace Materials and Performance (Ministry of Education), School of Materials Science and Engineering, Beijing University of Aeronautics and Astronautics, Beijing 100191 (China)], E-mail: wangximei126@126.com; Zhu Liqun; Li Weiping; Liu Huicong; Li Yihong [Key Laboratory of Aerospace Materials and Performance (Ministry of Education), School of Materials Science and Engineering, Beijing University of Aeronautics and Astronautics, Beijing 100191 (China)
2009-03-15
Anodic films have been prepared on the AZ91D magnesium alloys in 1 mol/L Na{sub 2}SiO{sub 3} with 10 vol.% silica sol addition under the constant voltage of 60 V at room temperature by half-wave and full-wave power sources. The weight of the anodic films has been scaled by analytical balance, and the thickness has been measured by eddy current instrument. The surface morphologies, chemical composition and structure of the anodic films have been characterized by scanning electron microscopy (SEM), energy dispersion spectrometry (EDS), X-ray diffraction (XRD) and transmission electron microscopy (TEM). The results show that the thickness and weight of the anodic films formed by the two power sources both increase with the anodizing time, and the films anodized by full-wave power source grow faster than that by half-wave one. Furthermore, we have fitted polynomial to the scattered data of the weight and thickness in a least-squares sense with MATLAB, which could express the growth process of the anodic films sufficiently. The full-wave power source is inclined to accelerate the growth of the anodic films, and the half-wave one is mainly contributed to the uniformity and fineness of the films. The anodic film consists of crystalline Mg{sub 2}SiO{sub 4} and amorphous SiO{sub 2}.
Analytic perturbation theory for screened Coulomb potential: full continuum wave function
International Nuclear Information System (INIS)
Bechler, A.; Ennan, Mc J.; Pratt, R.H.
1979-01-01
An analytic perturbation theory developed previously is used to find a continuum screened-Coulomb wave function characterized by definite asymptotic momentum. This wave function satisfies an inhomogeneous partial differential equation which is solved in parabolic coordinates; the solution depends on both parabolic variables. We calculate partial wave projections of this solution and show that we can choose to add a solution of the homogeneous equation such that the partial wave projections become equal to the normalized continuum radial function found previously. However, finding the unique solution with given asymptotic linear momentum will require either using boundary conditions to determine the unique needed solution of the homogeneous equation or equivalently specifying the screened-Coulomb phase-shifts. (author)
Full-wave Ambient Noise Tomography of Mt Rainier volcano, USA
Flinders, Ashton; Shen, Yang
2015-04-01
Mount Rainier towers over the landscape of western Washington (USA), ranking with Fuji-yama in Japan, Mt Pinatubo in the Philippines, and Mt Vesuvius in Italy, as one of the great stratovolcanoes of the world. Notwithstanding its picturesque stature, Mt Rainier is potentially the most devastating stratovolcano in North America, with more than 3.5 million people living beneath is shadow in the Seattle-Tacoma area. The primary hazard posed by the volcano is in the form of highly destructive debris flows (lahars). These lahars form when water and/or melted ice erode away and entrain preexisting volcanic sediment. At Mt Rainier these flows are often initiated by sector collapse of the volcano's hydrothermally rotten flanks and compounded by Mt Rainier's extensive snow and glacial ice coverage. It is therefore imperative to ascertain the extent of the volcano's summit hydrothermal alteration, and determine areas prone to collapse. Despite being one of the sixteen volcanoes globally designated by the International Association of Volcanology and Chemistry of the Earth's Interior as warranting detailed and focused study, Mt Rainier remains enigmatic both in terms of the shallow internal structure and the degree of summit hydrothermal alteration. We image this shallow internal structure and areas of possible summit alteration using ambient noise tomography. Our full waveform forward modeling includes high-resolution topography allowing us to accuratly account for the effects of topography on the propagation of short-period Rayleigh waves. Empirical Green's functions were extracted from 80 stations within 200 km of Mt Rainier, and compared with synthetic greens functions over multiple frequency bands from 2-28 seconds.
Jacobs, Christopher
2015-08-01
ICRF-3 seeks to improve upon the highly successful ICRF-2. Our goals are to improve the precision, spatial and frequency coverage relative to the ICRF-2 by 2018. This date is driven by the desire to create radio frames that are ready for comparison with the Gaia optical frame.Several specific actions are underway. A collaboration to improve at S/X-band precision of the Very Long Baseline Array (VLBA) Calibrator Survey's ~2200 sources, which are typically 5 times less precise than the rest of the ICRF-2, is bearing fruit and is projected to yield a factor of 3 improvement in precision. S/X-band southern hemisphere precision improvements are underway with observations using southern antennas such as the AuScope, Warkworth, and HartRAO, South Africa.We also seek to improve radio frequency coverage with X/Ka-band and K-band work. An X/Ka frame of 660 sources now has full sky coverage from the addition of a 2nd southern station in Argentina which is strengthening the southern hemisphere in general. The X/Ka-band frame's precision is now comparable to the ICRF-2 for the 530 sources in common. A K-band collaboration has formed with similar coverage and southern precision goals. By the time of this meeting, we expect K-band to complete full sky coverage with south polar cap observations and to improve spatial density north of -30 deg declination with VLBA observations.On the analysis front, special attention is being given to combination techniques both of Very Long Baseline Interferometry (VLBI) frames and of multiple data types. Consistency of the Celestial Reference Frame (CRF) with the Terrestrial Reference Frame (TRF) and Earth Oreintation Parameters (EOP) is another area of concern. Comparison of celestial frame solutions from various groups is underway in order to identify and correct systematic errors. We will discuss evidence emerging for 100 µas zonal errors in the ICRF2 in the declination range from 0 to -30 deg.Finally, work is underway to identify and
Traveling-wave reactors: A truly sustainable and full-scale resource for global energy needs
International Nuclear Information System (INIS)
Ellis, T.; Petroski, R.; Hejzlar, P.; Zimmerman, G.; McAlees, D.; Whitmer, C.; Touran, N.; Hejzlar, J.; Weave, K.; Walter, J. C.; McWhirter, J.; Ahlfeld, C.; Burke, T.; Odedra, A.; Hyde, R.; Gilleland, J.; Ishikawa, Y.; Wood, L.; Myhrvold, N.; Gates Iii, W. H.
2010-01-01
Rising environmental and economic concerns have signaled a desire to reduce dependence on hydrocarbon fuels. These concerns have brought the world to an inflection point and decisions made today will dictate what the global energy landscape will look like for the next half century or more. An optimal energy technology for the future must meet stricter standards than in the past; in addition to being economically attractive, it now must also be environmentally benign, sustainable and scalable to global use. For stationary energy, only one existing resource comes close to fitting all of the societal requirements for an optimal energy source: nuclear energy. Its demonstrated economic performance, power density, and emissions-free benefits significantly elevate nuclear electricity generation above other energy sources. However, the current nuclear fuel cycle has some attributes that make it challenging to expand on a global scale. Traveling-wave reactor (TWR) technology, being developed by TerraPower, LLC, represents a potential solution to these limitations by offering a nuclear energy resource which is truly sustainable at full global scale for the indefinite future and is deployable in the near-term. TWRs are capable of offering a ∼40-fold gain in fuel utilization efficiency compared to conventional light-water reactors burning enriched fuel. Such high fuel efficiency, combined with an ability to use uranium recovered from river water or sea-water (which has been recently demonstrated to be technically and economically feasible) suggests that enough fuel is readily available for TWRs to generate electricity for 10 billion people at United States per capita levels for million-year time-scales. Interestingly, the Earth's rivers carry into the ocean a flux of uranium several times greater than that required to replace the implied rate-of-consumption, so that the Earth's slowly-eroding crust will provide a readily-accessible flow of uranium sufficient for all of
Heat Loads On Tore Supra ICRF Launchers Plasma Facing Components
International Nuclear Information System (INIS)
Bremond, S.; Colas, L.; Chantant, M.; Beaumont, B.; Ekedahl, A.; Goniche, M.; Moreau, P.; Mitteau, R.
2005-01-01
Understanding the heat loads on Ion Cyclotron Range of Frequency launchers plasma facing components is a crucial task both for operating present tokamaks and for designing ITER ICRF launchers as these loads may limit the RF power coupling capability. Tore Supra facility is particularly well suited to take this issue. Parametric studies have been performed which enables to get an overall detailed picture of the different heat loads on several areas, pointing to different mechanisms at the origin of the heat power fluxes. Lessons are drawned both with regards to Tore Supra possible operational limits and to ITER ICRF launcher design
ICRF heating of passing ions in TMX-U
International Nuclear Information System (INIS)
Molvik, A.W.; Dimonte, G.; Barter, J.; Campbell, R.; Cummins, W.F.; Falabella, S.; Ferguson, S.W.; Poulsen, P.
1986-04-01
By placing ion-cyclotron resonant frequency (ICRF) antennas on both sides of a midplane gas-feed system in the central cell of the Tandem Mirror Experiment-Upgrade (TMX-U), our results have improved in the following areas: (a) The end losses out both ends show a factor of 3 to 4 increase in passing-ion temperatures and a factor of 2 to 3 decrease in passing-ion densities. (b) The passing-ion heating is consistent with Monte Carlo predictions. (c) The plasma density can be sustained by ICRF plus gas fueling as observed on other experiments
Ripple losses during ICRF heating in Tore Supra
International Nuclear Information System (INIS)
Basiuk, V.; Eriksson, L.-G.; Bergeaud, V.; Chantant, M.; Martin, G.; Nguyen, F.; Reichle, R.; Vallet, J.C.; Delpeche, L.; Surle, F.
2004-01-01
The toroidal field coils in Tore Supra are supra-conducting, and their number is restricted to 18. As a result, the ripple is fairly large, about 7% at the plasma boundary. Tore Supra has consequently been equipped with dedicated ripple loss diagnostics, which has allowed ripple loss studies. This paper reports on the measurements made with these diagnostics and provides an analysis of the experimental results, comparing them with theoretical expectations whenever possible. Furthermore, the main heating source accelerating ions in Tore Supra is ion cyclotron resonance range of frequency (ICRF) heating, and the paper provides new information on the ripple losses of ICRF accelerated ions. (author)
Propagation characteristics of electromagnetic waves in dusty plasma with full ionization
Dan, Li; Guo, Li-Xin; Li, Jiang-Ting
2018-01-01
This study investigates the propagation characteristics of electromagnetic (EM) waves in fully ionized dusty plasmas. The propagation characteristics of fully ionized plasma with and without dust under the Fokker-Planck-Landau (FPL) and Bhatnagar-Gross-Krook (BGK) models are compared to those of weakly ionized plasmas by using the propagation matrix method. It is shown that the FPL model is suitable for the analysis of the propagation characteristics of weakly collisional and fully ionized dusty plasmas, as is the BGK model. The influence of varying the dust parameters on the propagation properties of EM waves in the fully ionized dusty plasma was analyzed using the FPL model. The simulation results indicated that the densities and average radii of dust grains influence the reflection and transmission coefficients of fully ionized dusty plasma slabs. These results may be utilized to analyze the effects of interaction between EM waves and dusty plasmas, such as those associated with hypersonic vehicles.
Resonant Wave Energy Converters: Small-scale field experiments and first full-scale prototype
International Nuclear Information System (INIS)
Arena, Felice; Fiamma, Vincenzo; Iannolo, Roberto; Laface, Valentina; Malara, Giovanni; Romolo, Alessandra; Strati Federica Maria
2015-01-01
The Resonant Wave Energy Converter 3 (REWEC3) is a device belonging to the family of Oscillating Water Columns (OWCs), that can convert the energy of incident waves into electrical energy via turbines. In contrast to classical OWCs, it incorporates a small vertical U-shaped duct to connect the water column to the open wave field. This article shows the results of a small-scale field experiment involving a REWEC3 designed for working with a 2 kW turbine. Then, the next experimental activity on a REWEC3 installed in the NOEL laboratory with the collaboration of ENEA, is presented. Finally, the first prototype of ReWEC3 under construction in Civitavecchia (Rome, Italy) is shown. The crucial features of the construction stage are discussed and some initial performances are provided. [it
Full-Scale Testing of Pipeline Unplugging Technologies - NuVision's Fluidic Wave-Action Technology
International Nuclear Information System (INIS)
Gokaltun, S.; McDaniel, D.; Varona, J.; Patel, R.; Awwad, A.; Roelant, D.; Keszler, E.
2009-01-01
In this paper, we present a technical evaluation of a pipeline unplugging method that can be used as a feasible tool to clean fouled pipes at Department of Energy (DOE) sites. The unplugging method depends on running water against the plugged section in the pipeline for multiple times and breaking the mechanical bonds of the material that hold the plug together. The working principles of the method are similar to beach erosion since a water wave is generated using the suction and drive mechanisms caused by the system in the pipeline that erodes the plug from one end. The technology tested also is capable of creating an external force on the plug that helps the unplugging process however this characteristic of the technology was not tested during the testing reported in this work. More focus was given to the erosion capability of the technology and how wave characteristics affected that. Results obtained demonstrated that there is a correlation between the suction and drive characteristics of the wave generated in the pipeline with the maximum pressures attained in the plug region, the velocity of the wave prior to colliding with the plug and the erosion. It was found that the technology was most effective in unplugging Phosphate based chemical plugs and Kaolin clay based plugs while it took more time to erode Aluminum based plugs for the same pipeline test layouts. (authors)
Modeling of high power ICRF heating experiments on TFTR
International Nuclear Information System (INIS)
Phillips, C.K.; Wilson, J.R.; Bell, M.; Fredrickson, E.; Hosea, J.C.; Majeski, R.; Ramsey, A.; Rogers, J.H.; Schilling, G.; Skinner, C.; Stevens, J.E.; Taylor, G.; Wong, K.L.; Murakami, M.
1993-01-01
Over the past two years, ICRF heating experiments have been performed on TFTR in the hydrogen minority heating regime with power levels reaching 11.2 MW in helium-4 majority plasmas and 8.4 MW in deuterium majority plasmas. For these power levels, the minority hydrogen ions, which comprise typically less than 10% of the total electron density, evolve into la very energetic, anisotropic non-Maxwellian distribution. Indeed, the excess perpendicular stored energy in these plasmas associated with the energetic minority tail ions is often as high as 25% of the total stored energy, as inferred from magnetic measurements. Enhanced losses of 0.5 MeV protons consistent with the presence of an energetic hydrogen component have also been observed. In ICRF heating experiments on JET at comparable and higher power levels and with similar parameters, it has been suggested that finite banana width effects have a noticeable effect on the ICRF power deposition. In particular, models indicate that finite orbit width effects lead to a reduction in the total stored energy and of the tail energy in the center of the plasma, relative to that predicted by the zero banana width models. In this paper, detailed comparisons between the calculated ICRF power deposition profiles and experimentally measured quantities will be presented which indicate that significant deviations from the zero banana width models occur even for modest power levels (P rf ∼ 6 MW) in the TFTR experiments
Advanced ponderomotive description of electron acceleration in ICRF discharge initiation
Directory of Open Access Journals (Sweden)
Wauters Tom
2017-01-01
An example for plasma production by the TOMAS ICRF system is given. Following the described conditions it can be derived that plasma production is (i most efficient close to the antenna straps (few cm's where the field gradient and amplitude are large, and (ii that the lower frequency field accelerates electrons more easily for a given antenna voltage.
2-D mapping of ICRF-induced SOL perturbations in
Czech Academy of Sciences Publication Activity Database
Colas, L.; Gunn, J. P.; Nanobashvili, I.; Petržílka, Václav; Goniche, M.; Ekedahl, A.; Heuraux, S.; Joffrin, E.; Saint Laurent, F.; Balorin, C.; Lowry, C.; Basiuk, V.
363-365, č. 4 (2007), s. 555-559 ISSN 0022-3115 R&D Projects: GA ČR GA202/04/0360 Institutional research plan: CEZ:AV0Z20430508 Keywords : ICRF antenna * plasma Subject RIV: BL - Plasma and Gas Discharge Physics Impact factor: 1.643, year: 2007
Modal approach for the full simulation of nondestructive tests by elastic guided waves
International Nuclear Information System (INIS)
Jezzine, K.
2006-11-01
Tools for simulating nondestructive tests by elastic guided waves are developed. Two overall formulations based on modal formalism and reciprocity are derived depending on whether transmission and reception are separated or not. They relate phenomena of guided wave radiation by a transducer, their propagation, their scattering by a non-uniformity of the guide or a defect and their reception. Receiver electrical output is expressed as a product of terms relating to each phenomenon that can be computed separately. Their computation uses developments based on the semi-analytical finite elements method, dealing with guides of arbitrary cross-section and cracks normal to the guide axis. Simulation tools are used to study means for selecting a single mode using a transducer positioned on the guide section, such a selection making easier the interpretation of the results of testing by guided waves. Two methods of mode selection are proposed, based on the use of two specific frequencies (which existence depends on guide geometry and mode symmetry). Mimicking the normal stress distribution of the mode at one of these two frequencies or the other makes it possible to radiate solely or predominantly the mode chosen. Examinations are simulated in configurations using a single or two separated transducers positioned on the section of various guide geometries and cracks of various shapes. The interest and performances of the two methods of mode selection are studied in these configurations. (author)
Parisi, Laura
2016-02-10
The surface wave full ray theory (FRT) is an efficient tool to calculate synthetic waveforms of surface waves. It combines the concept of local modes with exact ray tracing as a function of frequency, providing a more complete description of surface wave propagation than the widely used great circle approximation (GCA). The purpose of this study is to evaluate the ability of the FRT approach to model teleseismic long-period surface waveforms (T ∼ 45–150 s) in the context of current 3-D Earth models to empirically assess its validity domain and its scope for future studies in seismic tomography. To achieve this goal, we compute vertical and horizontal component fundamental mode synthetic Rayleigh waveforms using the FRT, which are compared with calculations using the highly accurate spectral element method. We use 13 global earth models including 3-D crustal and mantle structure, which are derived by successively varying the strength and lengthscale of heterogeneity in current tomographic models. For completeness, GCA waveforms are also compared with the spectral element method. We find that the FRT accurately predicts the phase and amplitude of long-period Rayleigh waves (T ∼ 45–150 s) for almost all the models considered, with errors in the modelling of the phase (amplitude) of Rayleigh waves being smaller than 5 per cent (10 per cent) in most cases. The largest errors in phase and amplitude are observed for T ∼ 45 s and for the three roughest earth models considered that exhibit shear wave anomalies of up to ∼20 per cent, which is much larger than in current global tomographic models. In addition, we find that overall the GCA does not predict Rayleigh wave amplitudes well, except for the longest wave periods (T ∼ 150 s) and the smoothest models considered. Although the GCA accurately predicts Rayleigh wave phase for current earth models such as S20RTS and S40RTS, FRT\\'s phase errors are smaller, notably for the shortest wave periods considered (T
A global simulation of ICRF heating in a 3D magnetic configuration
International Nuclear Information System (INIS)
Murakami, S.; Fukuyama, A.; Akutsu, T.
2005-01-01
A global simulation code for the ICRF heating analysis in a three-dimensional (3D) magnetic configuration is developed combining two global simulation codes; a drift kinetic equation solver, GNET, and a wave field solver, TASK/WM. Both codes take into account 3D geometry using the numerically obtained 3D MHD equilibrium. The developed simulation code is applied to the LHD configuration as an example. Characteristics of energetic ion distributions in the phase space are clarified in LHD. The simulation results are also compared with experimental results by evaluating the count number of the neutral particle analyzer using the obtained energetic ion distribution, and a relatively good agreement is obtained. (author)
Full band all-sky search for periodic gravitational waves in the O1 LIGO data
Abbott, B. P.; Abbott, R.; Abbott, T. D.; Acernese, F.; Ackley, K.; Adams, C.; Adams, T.; Addesso, P.; Adhikari, R. X.; Adya, V. B.; Affeldt, C.; Afrough, M.; Agarwal, B.; Agathos, M.; Agatsuma, K.; Aggarwal, N.; Aguiar, O. D.; Aiello, L.; Ain, A.; Allen, B.; Allen, G.; Allocca, A.; Altin, P. A.; Amato, A.; Ananyeva, A.; Anderson, S. B.; Anderson, W. G.; Angelova, S. V.; Antier, S.; Appert, S.; Arai, K.; Araya, M. C.; Areeda, J. S.; Arnaud, N.; Ascenzi, S.; Ashton, G.; Ast, M.; Aston, S. M.; Astone, P.; Atallah, D. V.; Aufmuth, P.; Aulbert, C.; AultONeal, K.; Austin, C.; Avila-Alvarez, A.; Babak, S.; Bacon, P.; Bader, M. K. M.; Bae, S.; Baker, P. T.; Baldaccini, F.; Ballardin, G.; Ballmer, S. W.; Banagiri, S.; Barayoga, J. C.; Barclay, S. E.; Barish, B. C.; Barker, D.; Barkett, K.; Barone, F.; Barr, B.; Barsotti, L.; Barsuglia, M.; Barta, D.; Bartlett, J.; Bartos, I.; Bassiri, R.; Basti, A.; Batch, J. C.; Bawaj, M.; Bayley, J. C.; Bazzan, M.; Bécsy, B.; Beer, C.; Bejger, M.; Belahcene, I.; Bell, A. S.; Berger, B. K.; Bergmann, G.; Bero, J. J.; Berry, C. P. L.; Bersanetti, D.; Bertolini, A.; Betzwieser, J.; Bhagwat, S.; Bhandare, R.; Bilenko, I. A.; Billingsley, G.; Billman, C. R.; Birch, J.; Birney, R.; Birnholtz, O.; Biscans, S.; Biscoveanu, S.; Bisht, A.; Bitossi, M.; Biwer, C.; Bizouard, M. A.; Blackburn, J. K.; Blackman, J.; Blair, C. D.; Blair, D. G.; Blair, R. M.; Bloemen, S.; Bock, O.; Bode, N.; Boer, M.; Bogaert, G.; Bohe, A.; Bondu, F.; Bonilla, E.; Bonnand, R.; Boom, B. A.; Bork, R.; Boschi, V.; Bose, S.; Bossie, K.; Bouffanais, Y.; Bozzi, A.; Bradaschia, C.; Brady, P. R.; Branchesi, M.; Brau, J. E.; Briant, T.; Brillet, A.; Brinkmann, M.; Brisson, V.; Brockill, P.; Broida, J. E.; Brooks, A. F.; Brown, D. A.; Brown, D. D.; Brunett, S.; Buchanan, C. C.; Buikema, A.; Bulik, T.; Bulten, H. J.; Buonanno, A.; Buskulic, D.; Buy, C.; Byer, R. L.; Cabero, M.; Cadonati, L.; Cagnoli, G.; Cahillane, C.; Bustillo, J. Calderón; Callister, T. A.; Calloni, E.; Camp, J. B.; Canepa, M.; Canizares, P.; Cannon, K. C.; Cao, H.; Cao, J.; Capano, C. D.; Capocasa, E.; Carbognani, F.; Caride, S.; Carney, M. F.; Casanueva Diaz, J.; Casentini, C.; Caudill, S.; Cavaglià, M.; Cavalier, F.; Cavalieri, R.; Cella, G.; Cepeda, C. B.; Cerdá-Durán, P.; Cerretani, G.; Cesarini, E.; Chamberlin, S. J.; Chan, M.; Chao, S.; Charlton, P.; Chase, E.; Chassande-Mottin, E.; Chatterjee, D.; Cheeseboro, B. D.; Chen, H. Y.; Chen, X.; Chen, Y.; Cheng, H.-P.; Chia, H. Y.; Chincarini, A.; Chiummo, A.; Chmiel, T.; Cho, H. S.; Cho, M.; Chow, J. H.; Christensen, N.; Chu, Q.; Chua, A. J. K.; Chua, S.; Chung, A. K. W.; Chung, S.; Ciani, G.; Ciecielag, P.; Ciolfi, R.; Cirelli, C. E.; Cirone, A.; Clara, F.; Clark, J. A.; Clearwater, P.; Cleva, F.; Cocchieri, C.; Coccia, E.; Cohadon, P.-F.; Cohen, D.; Colla, A.; Collette, C. G.; Cominsky, L. R.; Constancio, M.; Conti, L.; Cooper, S. J.; Corban, P.; Corbitt, T. R.; Cordero-Carrión, I.; Corley, K. R.; Cornish, N.; Corsi, A.; Cortese, S.; Costa, C. A.; Coughlin, E. T.; Coughlin, M. W.; Coughlin, S. B.; Coulon, J.-P.; Countryman, S. T.; Couvares, P.; Covas, P. B.; Cowan, E. E.; Coward, D. M.; Cowart, M. J.; Coyne, D. C.; Coyne, R.; Creighton, J. D. E.; Creighton, T. D.; Cripe, J.; Crowder, S. G.; Cullen, T. J.; Cumming, A.; Cunningham, L.; Cuoco, E.; Canton, T. Dal; Dálya, G.; Danilishin, S. L.; D'Antonio, S.; Danzmann, K.; Dasgupta, A.; Da Silva Costa, C. F.; Dattilo, V.; Dave, I.; Davier, M.; Davis, D.; Daw, E. J.; Day, B.; De, S.; DeBra, D.; Degallaix, J.; De Laurentis, M.; Deléglise, S.; Del Pozzo, W.; Demos, N.; Denker, T.; Dent, T.; De Pietri, R.; Dergachev, V.; De Rosa, R.; DeRosa, R. T.; De Rossi, C.; DeSalvo, R.; de Varona, O.; Devenson, J.; Dhurandhar, S.; Díaz, M. C.; Di Fiore, L.; Di Giovanni, M.; Di Girolamo, T.; Di Lieto, A.; Di Pace, S.; Di Palma, I.; Di Renzo, F.; Doctor, Z.; Dolique, V.; Donovan, F.; Dooley, K. L.; Doravari, S.; Dorosh, O.; Dorrington, I.; Douglas, R.; Dovale Álvarez, M.; Downes, T. P.; Drago, M.; Dreissigacker, C.; Driggers, J. C.; Du, Z.; Ducrot, M.; Dupej, P.; Dwyer, S. E.; Edo, T. B.; Edwards, M. C.; Effler, A.; Eggenstein, H.-B.; Ehrens, P.; Eichholz, J.; Eikenberry, S. S.; Eisenstein, R. A.; Essick, R. C.; Estevez, D.; Etienne, Z. B.; Etzel, T.; Evans, M.; Evans, T. M.; Factourovich, M.; Fafone, V.; Fair, H.; Fairhurst, S.; Fan, X.; Farinon, S.; Farr, B.; Farr, W. M.; Fauchon-Jones, E. J.; Favata, M.; Fays, M.; Fee, C.; Fehrmann, H.; Feicht, J.; Fejer, M. M.; Fernandez-Galiana, A.; Ferrante, I.; Ferreira, E. C.; Ferrini, F.; Fidecaro, F.; Finstad, D.; Fiori, I.; Fiorucci, D.; Fishbach, M.; Fisher, R. P.; Fitz-Axen, M.; Flaminio, R.; Fletcher, M.; Fong, H.; Font, J. A.; Forsyth, P. W. F.; Forsyth, S. S.; Fournier, J.-D.; Frasca, S.; Frasconi, F.; Frei, Z.; Freise, A.; Frey, R.; Frey, V.; Fries, E. M.; Fritschel, P.; Frolov, V. V.; Fulda, P.; Fyffe, M.; Gabbard, H.; Gadre, B. U.; Gaebel, S. M.; Gair, J. R.; Gammaitoni, L.; Ganija, M. R.; Gaonkar, S. G.; Garcia-Quiros, C.; Garufi, F.; Gateley, B.; Gaudio, S.; Gaur, G.; Gayathri, V.; Gehrels, N.; Gemme, G.; Genin, E.; Gennai, A.; George, D.; George, J.; Gergely, L.; Germain, V.; Ghonge, S.; Ghosh, Abhirup; Ghosh, Archisman; Ghosh, S.; Giaime, J. A.; Giardina, K. D.; Giazotto, A.; Gill, K.; Glover, L.; Goetz, E.; Goetz, R.; Gomes, S.; Goncharov, B.; González, G.; Gonzalez Castro, J. M.; Gopakumar, A.; Gorodetsky, M. L.; Gossan, S. E.; Gosselin, M.; Gouaty, R.; Grado, A.; Graef, C.; Granata, M.; Grant, A.; Gras, S.; Gray, C.; Greco, G.; Green, A. C.; Gretarsson, E. M.; Groot, P.; Grote, H.; Grunewald, S.; Gruning, P.; Guidi, G. M.; Guo, X.; Gupta, A.; Gupta, M. K.; Gushwa, K. E.; Gustafson, E. K.; Gustafson, R.; Halim, O.; Hall, B. R.; Hall, E. D.; Hamilton, E. Z.; Hammond, G.; Haney, M.; Hanke, M. M.; Hanks, J.; Hanna, C.; Hannam, M. D.; Hannuksela, O. A.; Hanson, J.; Hardwick, T.; Harms, J.; Harry, G. M.; Harry, I. W.; Hart, M. J.; Haster, C.-J.; Haughian, K.; Healy, J.; Heidmann, A.; Heintze, M. C.; Heitmann, H.; Hello, P.; Hemming, G.; Hendry, M.; Heng, I. S.; Hennig, J.; Heptonstall, A. W.; Heurs, M.; Hild, S.; Hinderer, T.; Hoak, D.; Hofman, D.; Holt, K.; Holz, D. E.; Hopkins, P.; Horst, C.; Hough, J.; Houston, E. A.; Howell, E. J.; Hreibi, A.; Hu, Y. M.; Huerta, E. A.; Huet, D.; Hughey, B.; Husa, S.; Huttner, S. H.; Huynh-Dinh, T.; Indik, N.; Inta, R.; Intini, G.; Isa, H. N.; Isac, J.-M.; Isi, M.; Iyer, B. R.; Izumi, K.; Jacqmin, T.; Jani, K.; Jaranowski, P.; Jawahar, S.; Jiménez-Forteza, F.; Johnson, W. W.; Jones, D. I.; Jones, R.; Jonker, R. J. G.; Ju, L.; Junker, J.; Kalaghatgi, C. V.; Kalogera, V.; Kamai, B.; Kandhasamy, S.; Kang, G.; Kanner, J. B.; Kapadia, S. J.; Karki, S.; Karvinen, K. S.; Kasprzack, M.; Katolik, M.; Katsavounidis, E.; Katzman, W.; Kaufer, S.; Kawabe, K.; Kéfélian, F.; Keitel, D.; Kemball, A. J.; Kennedy, R.; Kent, C.; Key, J. S.; Khalili, F. Y.; Khan, I.; Khan, S.; Khan, Z.; Khazanov, E. A.; Kijbunchoo, N.; Kim, Chunglee; Kim, J. C.; Kim, K.; Kim, W.; Kim, W. S.; Kim, Y.-M.; Kimbrell, S. J.; King, E. J.; King, P. J.; Kinley-Hanlon, M.; Kirchhoff, R.; Kissel, J. S.; Kleybolte, L.; Klimenko, S.; Knowles, T. D.; Koch, P.; Koehlenbeck, S. M.; Koley, S.; Kondrashov, V.; Kontos, A.; Korobko, M.; Korth, W. Z.; Kowalska, I.; Kozak, D. B.; Krämer, C.; Kringel, V.; Krishnan, B.; Królak, A.; Kuehn, G.; Kumar, P.; Kumar, R.; Kumar, S.; Kuo, L.; Kutynia, A.; Kwang, S.; Lackey, B. D.; Lai, K. H.; Landry, M.; Lang, R. N.; Lange, J.; Lantz, B.; Lanza, R. K.; Lartaux-Vollard, A.; Lasky, P. D.; Laxen, M.; Lazzarini, A.; Lazzaro, C.; Leaci, P.; Leavey, S.; Lee, C. H.; Lee, H. K.; Lee, H. M.; Lee, H. W.; Lee, K.; Lehmann, J.; Lenon, A.; Leonardi, M.; Leroy, N.; Letendre, N.; Levin, Y.; Li, T. G. F.; Linker, S. D.; Littenberg, T. B.; Liu, J.; Lo, R. K. L.; Lockerbie, N. A.; London, L. T.; Lord, J. E.; Lorenzini, M.; Loriette, V.; Lormand, M.; Losurdo, G.; Lough, J. D.; Lovelace, G.; Lück, H.; Lumaca, D.; Lundgren, A. P.; Lynch, R.; Ma, Y.; Macas, R.; Macfoy, S.; Machenschalk, B.; MacInnis, M.; Macleod, D. M.; Magaña Hernandez, I.; Magaña-Sandoval, F.; Magaña Zertuche, L.; Magee, R. M.; Majorana, E.; Maksimovic, I.; Man, N.; Mandic, V.; Mangano, V.; Mansell, G. L.; Manske, M.; Mantovani, M.; Marchesoni, F.; Marion, F.; Márka, S.; Márka, Z.; Markakis, C.; Markosyan, A. S.; Markowitz, A.; Maros, E.; Marquina, A.; Martelli, F.; Martellini, L.; Martin, I. W.; Martin, R. M.; Martynov, D. V.; Mason, K.; Massera, E.; Masserot, A.; Massinger, T. J.; Masso-Reid, M.; Mastrogiovanni, S.; Matas, A.; Matichard, F.; Matone, L.; Mavalvala, N.; Mazumder, N.; McCarthy, R.; McClelland, D. E.; McCormick, S.; McCuller, L.; McGuire, S. C.; McIntyre, G.; McIver, J.; McManus, D. J.; McNeill, L.; McRae, T.; McWilliams, S. T.; Meacher, D.; Meadors, G. D.; Mehmet, M.; Meidam, J.; Mejuto-Villa, E.; Melatos, A.; Mendell, G.; Mercer, R. A.; Merilh, E. L.; Merzougui, M.; Meshkov, S.; Messenger, C.; Messick, C.; Metzdorff, R.; Meyers, P. M.; Miao, H.; Michel, C.; Middleton, H.; Mikhailov, E. E.; Milano, L.; Miller, A. L.; Miller, B. B.; Miller, J.; Millhouse, M.; Milovich-Goff, M. C.; Minazzoli, O.; Minenkov, Y.; Ming, J.; Mishra, C.; Mitra, S.; Mitrofanov, V. P.; Mitselmakher, G.; Mittleman, R.; Moffa, D.; Moggi, A.; Mogushi, K.; Mohan, M.; Mohapatra, S. R. P.; Montani, M.; Moore, C. J.; Moraru, D.; Moreno, G.; Morriss, S. R.; Mours, B.; Mow-Lowry, C. M.; Mueller, G.; Muir, A. W.; Mukherjee, Arunava; Mukherjee, D.; Mukherjee, S.; Mukund, N.; Mullavey, A.; Munch, J.; Muñiz, E. A.; Muratore, M.; Murray, P. G.; Napier, K.; Nardecchia, I.; Naticchioni, L.; Nayak, R. K.; Neilson, J.; Nelemans, G.; Nelson, T. J. N.; Nery, M.; Neunzert, A.; Nevin, L.; Newport, J. M.; Newton, G.; Ng, K. Y.; Nguyen, T. T.; Nichols, D.; Nielsen, A. B.; Nissanke, S.; Nitz, A.; Noack, A.; Nocera, F.; Nolting, D.; North, C.; Nuttall, L. K.; Oberling, J.; O'Dea, G. D.; Ogin, G. H.; Oh, J. J.; Oh, S. H.; Ohme, F.; Okada, M. A.; Oliver, M.; Oppermann, P.; Oram, Richard J.; O'Reilly, B.; Ormiston, R.; Ortega, L. F.; O'Shaughnessy, R.; Ossokine, S.; Ottaway, D. J.; Overmier, H.; Owen, B. J.; Pace, A. E.; Page, J.; Page, M. A.; Pai, A.; Pai, S. A.; Palamos, J. R.; Palashov, O.; Palomba, C.; Pal-Singh, A.; Pan, Howard; Pan, Huang-Wei; Pang, B.; Pang, P. T. H.; Pankow, C.; Pannarale, F.; Pant, B. C.; Paoletti, F.; Paoli, A.; Papa, M. A.; Parida, A.; Parker, W.; Pascucci, D.; Pasqualetti, A.; Passaquieti, R.; Passuello, D.; Patil, M.; Patricelli, B.; Pearlstone, B. L.; Pedraza, M.; Pedurand, R.; Pekowsky, L.; Pele, A.; Penn, S.; Perez, C. J.; Perreca, A.; Perri, L. M.; Pfeiffer, H. P.; Phelps, M.; Piccinni, O. J.; Pichot, M.; Piergiovanni, F.; Pierro, V.; Pillant, G.; Pinard, L.; Pinto, I. M.; Pirello, M.; Pisarski, A.; Pitkin, M.; Poe, M.; Poggiani, R.; Popolizio, P.; Porter, E. K.; Post, A.; Powell, J.; Prasad, J.; Pratt, J. W. W.; Pratten, G.; Predoi, V.; Prestegard, T.; Prijatelj, M.; Principe, M.; Privitera, S.; Prodi, G. A.; Prokhorov, L. G.; Puncken, O.; Punturo, M.; Puppo, P.; Pürrer, M.; Qi, H.; Quetschke, V.; Quintero, E. A.; Quitzow-James, R.; Raab, F. J.; Rabeling, D. S.; Radkins, H.; Raffai, P.; Raja, S.; Rajan, C.; Rajbhandari, B.; Rakhmanov, M.; Ramirez, K. E.; Ramos-Buades, A.; Rapagnani, P.; Raymond, V.; Razzano, M.; Read, J.; Regimbau, T.; Rei, L.; Reid, S.; Reitze, D. H.; Ren, W.; Reyes, S. D.; Ricci, F.; Ricker, P. M.; Rieger, S.; Riles, K.; Rizzo, M.; Robertson, N. A.; Robie, R.; Robinet, F.; Rocchi, A.; Rolland, L.; Rollins, J. G.; Roma, V. J.; Romano, R.; Romel, C. L.; Romie, J. H.; Rosińska, D.; Ross, M. P.; Rowan, S.; Rüdiger, A.; Ruggi, P.; Rutins, G.; Ryan, K.; Sachdev, S.; Sadecki, T.; Sadeghian, L.; Sakellariadou, M.; Salconi, L.; Saleem, M.; Salemi, F.; Samajdar, A.; Sammut, L.; Sampson, L. M.; Sanchez, E. J.; Sanchez, L. E.; Sanchis-Gual, N.; Sandberg, V.; Sanders, J. R.; Sassolas, B.; Saulson, P. R.; Sauter, O.; Savage, R. L.; Sawadsky, A.; Schale, P.; Scheel, M.; Scheuer, J.; Schmidt, J.; Schmidt, P.; Schnabel, R.; Schofield, R. M. S.; Schönbeck, A.; Schreiber, E.; Schuette, D.; Schulte, B. W.; Schutz, B. F.; Schwalbe, S. G.; Scott, J.; Scott, S. M.; Seidel, E.; Sellers, D.; Sengupta, A. S.; Sentenac, D.; Sequino, V.; Sergeev, A.; Shaddock, D. A.; Shaffer, T. J.; Shah, A. A.; Shahriar, M. S.; Shaner, M. B.; Shao, L.; Shapiro, B.; Shawhan, P.; Sheperd, A.; Shoemaker, D. H.; Shoemaker, D. M.; Siellez, K.; Siemens, X.; Sieniawska, M.; Sigg, D.; Silva, A. D.; Singer, L. P.; Singh, A.; Singhal, A.; Sintes, A. M.; Slagmolen, B. J. J.; Smith, B.; Smith, J. R.; Smith, R. J. E.; Somala, S.; Son, E. J.; Sonnenberg, J. A.; Sorazu, B.; Sorrentino, F.; Souradeep, T.; Spencer, A. P.; Srivastava, A. K.; Staats, K.; Staley, A.; Steinke, M.; Steinlechner, J.; Steinlechner, S.; Steinmeyer, D.; Stevenson, S. P.; Stone, R.; Stops, D. J.; Strain, K. A.; Stratta, G.; Strigin, S. E.; Strunk, A.; Sturani, R.; Stuver, A. L.; Summerscales, T. Z.; Sun, L.; Sunil, S.; Suresh, J.; Sutton, P. J.; Swinkels, B. L.; Szczepańczyk, M. J.; Tacca, M.; Tait, S. C.; Talbot, C.; Talukder, D.; Tanner, D. B.; Tao, D.; Tápai, M.; Taracchini, A.; Tasson, J. D.; Taylor, J. A.; Taylor, R.; Tewari, S. V.; Theeg, T.; Thies, F.; Thomas, E. G.; Thomas, M.; Thomas, P.; Thorne, K. A.; Thrane, E.; Tiwari, S.; Tiwari, V.; Tokmakov, K. V.; Toland, K.; Tonelli, M.; Tornasi, Z.; Torres-Forné, A.; Torrie, C. I.; Töyrä, D.; Travasso, F.; Traylor, G.; Trinastic, J.; Tringali, M. C.; Trozzo, L.; Tsang, K. W.; Tse, M.; Tso, R.; Tsukada, L.; Tsuna, D.; Tuyenbayev, D.; Ueno, K.; Ugolini, D.; Unnikrishnan, C. S.; Urban, A. L.; Usman, S. A.; Vahlbruch, H.; Vajente, G.; Valdes, G.; van Bakel, N.; van Beuzekom, M.; van den Brand, J. F. J.; Van Den Broeck, C.; Vander-Hyde, D. C.; van der Schaaf, L.; van Heijningen, J. V.; van Veggel, A. A.; Vardaro, M.; Varma, V.; Vass, S.; Vasúth, M.; Vecchio, A.; Vedovato, G.; Veitch, J.; Veitch, P. J.; Venkateswara, K.; Venugopalan, G.; Verkindt, D.; Vetrano, F.; Viceré, A.; Viets, A. D.; Vinciguerra, S.; Vine, D. J.; Vinet, J.-Y.; Vitale, S.; Vo, T.; Vocca, H.; Vorvick, C.; Vyatchanin, S. P.; Wade, A. R.; Wade, L. E.; Wade, M.; Walet, R.; Walker, M.; Wallace, L.; Walsh, S.; Wang, G.; Wang, H.; Wang, J. Z.; Wang, W. H.; Wang, Y. F.; Ward, R. L.; Warner, J.; Was, M.; Watchi, J.; Weaver, B.; Wei, L.-W.; Weinert, M.; Weinstein, A. J.; Weiss, R.; Wen, L.; Wessel, E. K.; Weßels, P.; Westerweck, J.; Westphal, T.; Wette, K.; Whelan, J. T.; Whiting, B. F.; Whittle, C.; Wilken, D.; Williams, D.; Williams, R. D.; Williamson, A. R.; Willis, J. L.; Willke, B.; Wimmer, M. H.; Winkler, W.; Wipf, C. C.; Wittel, H.; Woan, G.; Woehler, J.; Wofford, J.; Wong, W. K.; Worden, J.; Wright, J. L.; Wu, D. S.; Wysocki, D. M.; Xiao, S.; Yamamoto, H.; Yancey, C. C.; Yang, L.; Yap, M. J.; Yazback, M.; Yu, Hang; Yu, Haocun; Yvert, M.; Zadroźny, A.; Zanolin, M.; Zelenova, T.; Zendri, J.-P.; Zevin, M.; Zhang, L.; Zhang, M.; Zhang, T.; Zhang, Y.-H.; Zhao, C.; Zhou, M.; Zhou, Z.; Zhu, S. J.; Zhu, X. J.; Zucker, M. E.; Zweizig, J.; LIGO Scientific Collaboration; Virgo Collaboration
2018-05-01
We report on a new all-sky search for periodic gravitational waves in the frequency band 475-2000 Hz and with a frequency time derivative in the range of [-1.0 ,+0.1 ] ×1 0-8 Hz /s . Potential signals could be produced by a nearby spinning and slightly nonaxisymmetric isolated neutron star in our Galaxy. This search uses the data from Advanced LIGO's first observational run O1. No gravitational-wave signals were observed, and upper limits were placed on their strengths. For completeness, results from the separately published low-frequency search 20-475 Hz are included as well. Our lowest upper limit on worst-case (linearly polarized) strain amplitude h0 is ˜4 ×1 0-25 near 170 Hz, while at the high end of our frequency range, we achieve a worst-case upper limit of 1.3 ×1 0-24. For a circularly polarized source (most favorable orientation), the smallest upper limit obtained is ˜1.5 ×1 0-25.
3D elastic full waveform inversion using P-wave excitation amplitude: Application to OBC field data
Oh, Juwon; Kalita, Mahesh; Alkhalifah, Tariq Ali
2017-01-01
We propose an efficient elastic full waveform inversion (FWI) based on the P-wave excitation amplitude (maximum energy arrival) approximation in the source wavefields. Because, based on the P-wave excitation approximation (ExA), the gradient direction is approximated by the cross-correlation of source and receiver wavefields at only excitation time, it estimates the gradient direction faster than its conventional counterpart. In addition to this computational speedup, the P-wave excitation approximation automatically ignores SP and SS correlations in the approximated gradient direction. In elastic FWI for ocean bottom cable (OBC) data, the descent direction for the S-wave velocity is often degraded by undesired long-wavelength features from the SS correlation. For this reason, the P-wave excitation approach increases the convergence rate of multi-parameter FWI compared to the conventional approach. The modified 2D Marmousi model with OBC acquisition is used to verify the differences between the conventional method and ExA. Finally, the feasibility of the proposed method is demonstrated on a real OBC data from North Sea.
3D elastic full waveform inversion using P-wave excitation amplitude: Application to OBC field data
Oh, Juwon
2017-12-05
We propose an efficient elastic full waveform inversion (FWI) based on the P-wave excitation amplitude (maximum energy arrival) approximation in the source wavefields. Because, based on the P-wave excitation approximation (ExA), the gradient direction is approximated by the cross-correlation of source and receiver wavefields at only excitation time, it estimates the gradient direction faster than its conventional counterpart. In addition to this computational speedup, the P-wave excitation approximation automatically ignores SP and SS correlations in the approximated gradient direction. In elastic FWI for ocean bottom cable (OBC) data, the descent direction for the S-wave velocity is often degraded by undesired long-wavelength features from the SS correlation. For this reason, the P-wave excitation approach increases the convergence rate of multi-parameter FWI compared to the conventional approach. The modified 2D Marmousi model with OBC acquisition is used to verify the differences between the conventional method and ExA. Finally, the feasibility of the proposed method is demonstrated on a real OBC data from North Sea.
Khushaini, Muhammad Asif A.; Ibrahim, Abdel-Baset M. A.; Choudhury, P. K.
2018-05-01
In this paper, we provide a complete mathematical model of the phenomenon of optical bistability (OB) resulting from the degenerate two-wave mixing (TWM) process of laser beams interacting with a single nonlinear layer of ferroelectric material. Starting with the electromagnetic wave equation for optical wave propagating in nonlinear media, a nonlinear coupled wave (CW) system with both self-phase modulation (SPM) and cross-phase modulation (XPM) sources of nonlinearity are derived. The complete CW system with full nonlinearity is solved numerically and a comparison between both the cases of with and without SPM at various combinations of design parameters is given. Furthermore, to provide a reliable theoretical model for the OB via TWM process, the results obtained theoretically are compared with the available experimental data. We found that the nonlinear system without SPM fails to predict the bistable response at lower combinations of the input parameters. However, at relatively higher values, the solution without SPM shows a reduction in the switching contrast and period in the OB response. A comparison with the experimental results shows better agreement with the system with full nonlinearity.
Extending the ICRF to Higher Radio Frequencies: 24 and 43 GHz Astrometry
Jacobs, Christopher S.; Charlot, Patrick; Fomalont, Ed B.; Gordon, David; Lanyi, Gabor E.; Ma, Chopo; Naudet, Charles J.; Sovers, Ojars J.; Zhang, Liwei D.; Kq VLBI Survey Collaboration
2004-06-01
Celestial reference frames have been constructed at K-band (24 GHz) and Q-band (43 GHz) based on VLBI astrometric survey observations of active galactic nuclei. Five VLBA observing sessions covered the full 24 hours of right ascension and declinations down to -44°. K-band's 230 sources have median formal position uncertainties of 150 and 290 μas in α cos δ and δ, respectively; the corresponding uncertainties for 132 Q-band sources are 215 and 360 μas, respectively. K-band weighted RMS (WRMS) residuals were 33 ps and 48 fs/s in delay and rate, respectively. Comparison of the K-band frame to the S/X-band ICRF shows WRMS agreement of 330 and 590 μas in α cos δ and δ, respectively. The motivations for extending the ICRF to higher frequencies are to use more compact sources to construct a more stable frame, to provide phase calibrators, and to support spacecraft navigation at Ka-band.
Bulk plasma rotation in the presence of waves in the ion cyclotron range of frequencies
International Nuclear Information System (INIS)
Eriksson, L.G.; Noterdaeme, J.M.; Kirov, K.
2003-01-01
Experiments with directed ICRF waves have for the first time in JET demonstrated the influence of absorbed wave momentum on bulk plasma rotation. Resonating fast ions acted as an intermediary in this process, and the experiments therefore provided evidence for the effect of fast ions on the plasma rotation. Results from these experiments are reviewed together with results from ICRF heated plasmas with symmetric spectra in JET and Tore Supra. The relevance of different theoretical models is briefly considered. (author)
Weerapon Kongnun; Phamorn Silapan
2013-01-01
The article presents a current-mode full-wave rectifier employing multiple output current follower transconductance amplifier (MO-CFTA). The both circuits description is very simple, it merely comprises only single MO-CFTA, without external passive element. In addition, the magnitude and direction of output currents can be controlled via electronically method. Furthermore, the outputs are independent of the thermal voltage (VT). The performances of the proposed circuits are investigated thro...
Monte-Carlo Orbit/Full Wave Simulation of Fast Alfvén Wave (FW) Damping on Resonant Ions in Tokamaks
Choi, M.; Chan, V. S.; Tang, V.; Bonoli, P.; Pinsker, R. I.; Wright, J.
2005-09-01
To simulate the resonant interaction of fast Alfvén wave (FW) heating and Coulomb collisions on energetic ions, including finite orbit effects, a Monte-Carlo code ORBIT-RF has been coupled with a 2D full wave code TORIC4. ORBIT-RF solves Hamiltonian guiding center drift equations to follow trajectories of test ions in 2D axisymmetric numerical magnetic equilibrium under Coulomb collisions and ion cyclotron radio frequency quasi-linear heating. Monte-Carlo operators for pitch-angle scattering and drag calculate the changes of test ions in velocity and pitch angle due to Coulomb collisions. A rf-induced random walk model describing fast ion stochastic interaction with FW reproduces quasi-linear diffusion in velocity space. FW fields and its wave numbers from TORIC are passed on to ORBIT-RF to calculate perpendicular rf kicks of resonant ions valid for arbitrary cyclotron harmonics. ORBIT-RF coupled with TORIC using a single dominant toroidal and poloidal wave number has demonstrated consistency of simulations with recent DIII-D FW experimental results for interaction between injected neutral-beam ions and FW, including measured neutron enhancement and enhanced high energy tail. Comparison with C-Mod fundamental heating discharges also yielded reasonable agreement.
Gabrielsson, Erik O; Janson, Per; Tybrandt, Klas; Simon, Daniel T; Berggren, Magnus
2014-08-13
Full-wave rectification of ionic currents is obtained by constructing the typical four-diode bridge out of ion conducting bipolar membranes. Together with conjugated polymer electrodes addressed with alternating current, the bridge allows for generation of a controlled ionic direct current for extended periods of time without the production of toxic species or gas typically arising from electrode side-reactions. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.
Enhanced Photocatalytic Activity of La3+-Doped TiO2 Nanotubes with Full Wave-Band Absorption
Xia, Minghao; Huang, Lingling; Zhang, Yubo; Wang, Yongqian
2018-06-01
TiO2 nanotubes doped with La3+ were synthesized by anodic oxidation method and the photocatalytic activity was detected by photodegrading methylene blue. As-prepared samples improved the absorption of both ultraviolet light and visible light and have a great enhancement on the photocatalytic activity while contrasting with the pristine TiO2 nanotubes. A tentative mechanism for the enhancement of photocatalytic activity with full wave-band absorption is proposed.
International Nuclear Information System (INIS)
Tian, F.; Tian, H.; Whitmore, L.; Ye, L.Y.
2015-01-01
The energy dependent on volume of hexagonal close-packed (hcp) nickel with different magnetism is calculated by full-potential linearized augmented plane wave method. Based on the calculation ferromagnetic state is found to be the most stable state. The magnetic moment of hcp Ni is calculated and compared to those calculated by different pseudo-potential methods. Furthermore, it is also compared to that of face-centered cubic (fcc) one with the reason discussed
RF field measurements in the vicinity of an ICRF antenna
International Nuclear Information System (INIS)
Majeski, R.; Intrator, T.; Roberts, D.; Hershkowitz, N.; Tataronis, J.; Grossmann, W.
1988-01-01
Measurements of the rf fields near an ICRF antenna installed in the central cell of the Phaedrus-B tandem mirror have been made, both in vacuum and in the presence of plasma. The antenna is a Faraday shielded partial turn loop. The front surface of the Faraday shield is composed of cylindrical elements in an arrangement similar to the Faraday shield design employed on TFTR. The antenna is run at relatively low power levels, in the 3.5-10 MHz frequency range. Two other ICRF systems in the phaedrus-B central cell sustain and heat the plasma at the 400 KW level. The vacuum field measurements are compared with the predictions of the ARGUS code, which models details of the Faraday shield structure. Fields in the plasma are modelled by the ANTENA code. Particle currents collected by the Faraday shield during plasma operation are also observed
Directory of Open Access Journals (Sweden)
S.Khanal
2012-06-01
Full Text Available This paper presents a fast and easy to use method to determine permittivity and loss tangent in the frequency range of 75 to 325 GHz. To obtain the permittivity and the loss tangent of the test material, the reflection and transmission S-parameters of a waveguide section filled with the test material are measured using a vector network analyzer and then compared with the simulated plots from a full wave simulator (HFSS, or alternatively the measurement results are used in mathematical formulas. The results are coherent over multiple waveguide bands.
DEFF Research Database (Denmark)
Guo, Kai; Friis, Søren Michael Mørk; Christensen, Jesper Bjerge
2017-01-01
We derive from Maxwell's equations full-vectorial nonlinear propagation equations of four-wave mixing valid in straight semiconductor-on-insulator waveguides. Special attention is given to the resulting effective mode area, which takes a convenient form known from studies in photonic crystal fibers......, but has not been introduced in the context of integrated waveguides. We show that the difference between our full-vectorial effective mode area and the scalar equivalent often referred to in the literature may lead to mistakes when evaluating the nonlinear refractive index and optimizing designs of new...
Full-field peak pressure prediction of shock waves from underwater explosion of cylindrical charges
Liu, Lei; Guo, Rui; Gao, Ke; Zeng, Ming Chao
2017-01-01
Cylindrical charge is a main form in most application of explosives. By employing numerical calculation and an indirect mapping method, the relation between peak pressures from underwater explosion of cylindrical and spherical charges is investigated, and further a model to predict full-field peak
Reduction in 14 MeV neutron generation rate by ICRF injection in D-3He burning plasmas
International Nuclear Information System (INIS)
Matsuura, Hideaki; Nakao, Yasuyuki
2004-01-01
The triton distribution function during ion cyclotron range of frequency (ICRF) waves injection in D- 3 He plasmas is examined by solving the 2-dimensional Fokker-Planck equation. Triton distribution function originally has a non-Maxwellian (tail) component around 1.01 MeV birth energy range due to D(d,p)T fusion reaction. Owing to the extension of the original tail by ICRF injection, the high-energy resonance tritons further increase, and the velocity-averaged T(d,n) 4 He fusion reaction rate coefficient, i.e. 14 MeV neutron generation rate, decreases from the values when triton is assumed to be Maxwellian. It is shown that when tritons absorb ∼1/200 of the fusion power from the waves in typical D- 3 He plasma, i.e. T=80 keV, n D =2x10 20 m -3 , τ E0 =3 sec and B=6T, the 14 MeV neutron generation rate is reduced by about ∼20% from the values for Maxwellian plasmas. (author)
Assessment of ICRF Antenna Performance in Alcator C-Mod
International Nuclear Information System (INIS)
Schilling, G.; Wukitch, S.J.; Lin, Y.; Basse, N.; Bonoli, P.T.; Edlund, E.; Lin, L.; Parisot, A.; Porkolab, M.
2004-01-01
The Alcator C-Mod has presented a challenge to install high-power ICRF antennas in a tight space. Modifications have been made to the antenna plasma-facing surfaces and the internal current-carrying structure in order to overcome performance limitations. At the present time, the antennas have exceeded 5 MW into plasma with heating phasing, up to 2.7 MW with current-drive phasing, with good efficiency and no deleterious effects
Recent results of JT-60U ICRF antenna operation
International Nuclear Information System (INIS)
Fujii, T.; Saigusa, M.; Kimura, H.
1994-01-01
Ion cyclotron range of frequencies (ICRF) heating is one of attractive plasma heating methods for reactor grade tokamaks, because it is quite effective in the wide ranges of plasma density and temperature. An antenna which should inject high power into plasma has been developed intensively because the heating efficiency and the coupling properties depend on its design. The antenna was operated at a small antenna-plasma gap in the JT-60 in out of phase mode, which showed the high heating efficiency to obtain high loading resistance, and similarly to other tokamaks. However, in order to reduce heat load to the antenna from plasma, a wide gap is required in reactor grade tokamaks such as ITER, in which the gap is designed to be 0.15 m in CDA. Two new antennas were fabricated for the JT-60U, which were designed to obtain high loading resistance at a wide gap for (π,0) phasing. The JT-60U ICRF heating system is explained. Also the JT-60U antenna is described. Antenna conditioning has been conducted well in the initial operation period. The phasing mode was set at (π,0) phasing, in which high heating efficiency is expected. The procedure is explained. The coupling and radiation loss properties during ICRF heating are reported. The JT-60U ICRF antennas were conditioned quickly with about 70 shots. The maximum coupled power was 6.4 MW for (π,0) phasing, and the power density was 6.1 MW/m 2 . (K.I.)
Directory of Open Access Journals (Sweden)
Mats Leijon
2013-05-01
Full Text Available Wave energy conversion is a clean electric power production technology. During operation there are no emissions in the form of harmful gases. However there are unsolved issues considering environmental impacts such as: electromagnetism; the artificial reef effect and underwater noise. Anthropogenic noise is increasing in the oceans worldwide and wave power will contribute to this sound pollution in the oceans; but to what extent? The main purpose of this study was to examine the noise emitted by a full scale operating Wave Energy Converter (WEC in the Lysekil project at Uppsala University in Sweden. A minor review of the hearing capabilities of fish and marine mammals is presented to aid in the conclusions of impact from anthropogenic sound. A hydrophone was deployed to the seabed in the Lysekil research site park at distance of 20 and 40 m away from two operational WECs. The measurements were performed in the spring of 2011. The results showed that the main noise was a transient noise with most of its energy in frequencies below 1 kHz. These results indicate that several marine organisms (fish and mammals will be able to hear the operating WECs of a distance of at least 20 m.
High Power RF Transmitters for ICRF Applications on EAST
International Nuclear Information System (INIS)
Mao Yuzhou; Yuan Shuai; Zhao Yanping; Zhang Xinjun; Chen Gen; Cheng Yan; Wang Lei; Ju Songqing; Deng Xu; Qin Chengming; Yang Lei; Kumazawa, R.
2013-01-01
An Ion Cyclotron Range of Frequency (ICRF) system with a radio frequency (RF) power of 4 × 1.5 MW was developed for the Experimental Advanced Superconducting Tokamak (EAST). High RF power transmitters were designed as a part of the research and development (R and D) for an ICRF system with long pulse operation at megawatt levels in a frequency range of 25 MHz to 70 MHz. Studies presented in this paper cover the following parts of the high power transmitter: the three staged high power amplifier, which is composed of a 5 kW wideband solid state amplifier, a 100 kW tetrode drive stage amplifier and a 1.5 MW tetrode final stage amplifier, and the DC high voltage power supply (HVPS). Based on engineering design and static examinations, the RF transmitters were tested using a matched dummy load where an RF output power of 1.5 MW was achieved. The transmitters provide 6 MW RF power in primary phase and will reach a level up to 12 MW after a later upgrade. The transmitters performed successfully in stable operations in EAST and HT-7 devices. Up to 1.8 MW of RF power was injected into plasmas in EAST ICRF heating experiments during the 2010 autumn campaign and plasma performance was greatly improved.
Characterization of local heat fluxes around ICRF antennas on JET
Energy Technology Data Exchange (ETDEWEB)
Campergue, A.-L. [Ecole Nationale des Ponts et Chaussées, F77455 Marne-la-Vallée (France); Jacquet, P.; Monakhov, I.; Arnoux, G.; Brix, M.; Sirinelli, A. [Euratom/CCFE Association, Culham Science Centre, Abingdon, OX14 3DB (United Kingdom); Bobkov, V. [Max-Planck-Institut für Plasmaphysik, EURATOM-Assoziation, Garching (Germany); Milanesio, D. [Politecnico di Torino, Department of Electronics, Torino (Italy); Colas, L. [CEA, IRFM, F-13108 Saint-Paul-Lez-Durance (France); Collaboration: JET-EFDA Contributors
2014-02-12
When using Ion Cyclotron Range of Frequency (ICRF) heating, enhanced power deposition on Plasma-Facing Components (PFCs) close to the antennas can occur. Experiments have recently been carried out on JET with the new ITER-Like-Wall (ILW) to characterize the heat fluxes on the protection of the JET ICRF antennas, using Infra-Red (IR) thermography measurement. The measured heat flux patterns along the poloidal limiters surrounding powered antennas were compared to predictions from a simple RF sheath rectification model. The RF electric field, parallel to the static magnetic field in front of the antenna, was evaluated using the TOPICA code, integrating a 3D flattened model of the JET A2 antennas. The poloidal density variation in front of the limiters was obtained from the mapping of the Li-beam or edge reflectometry measurements using the flux surface geometry provided by EFIT equilibrium reconstruction. In many cases, this simple model can well explain the position of the maximum heat flux on the different protection limiters and the heat-flux magnitude, confirming that the parallel RF electric field and the electron plasma density in front of the antenna are the main driving parameters for ICRF-induced local heat fluxes.
Energy Technology Data Exchange (ETDEWEB)
Inazaki, T [Geological Survey of Japan, Tsukuba (Japan); Kurahashi, T [Public Works Research Institute, Tsukuba (Japan); Goebuchi, T [OYO Corp., Tokyo (Japan)
1997-10-22
Full waveform digital sonic tool (OYO) has been developed for the purpose of accurately measuring geophysical anomalies in the rockbed containing cracks, and its performance is evaluated by comparing its measurements with those obtained by the conventional sonic logging device (DBM). Modification involves the following. While gain is fixed in the DBM, it is variable in a times10-times200 range in the OYO. Analog transfer:ground surface A/D in the DBM is replaced by digital transfer:intra-probe A/D in the OYO. In the DBM, only a special program running on the MS-DOS can analyze waveform data but, in the OYO, waveforms are recorded in the SEG-Y format enabling the import of the data into generally available waveform processing software. In the OYO, a high-speed communication board is incorporated into the probe, which realizes high-speed communication. There is a very excellent agreement between the two in P-wave velocity distribution as reckoned from the initial run. Regarding the OYO, however, it is pointed out that gain control be performed with the greatest care to prevent waveforms from distortion. 5 figs.
3D elastic full-waveform inversion for OBC data using the P-wave excitation amplitude
Oh, Juwon
2017-08-17
We suggest a fast and efficient 3D elastic full waveform inversion (FWI) algorithm based on the excitation amplitude (maximum energy arrival) of the P-wave in the source wavefield. It evaluates the gradient direction significantly faster than its conventional counterpart. In addition, it removes the long-wavelength artifacts from the gradient, which are often originated from SS correlation process. From these advantages, the excitation approach offers faster convergence not only for the S wave velocity, but also for the entire process of multi-parameter inversion, compared to the conventional FWI. The feasibility of the proposed method is demonstrated through the synthetic Marmousi and a real OBC data from North Sea.
3D elastic full-waveform inversion for OBC data using the P-wave excitation amplitude
Oh, Juwon; Kalita, Mahesh; Alkhalifah, Tariq Ali
2017-01-01
We suggest a fast and efficient 3D elastic full waveform inversion (FWI) algorithm based on the excitation amplitude (maximum energy arrival) of the P-wave in the source wavefield. It evaluates the gradient direction significantly faster than its conventional counterpart. In addition, it removes the long-wavelength artifacts from the gradient, which are often originated from SS correlation process. From these advantages, the excitation approach offers faster convergence not only for the S wave velocity, but also for the entire process of multi-parameter inversion, compared to the conventional FWI. The feasibility of the proposed method is demonstrated through the synthetic Marmousi and a real OBC data from North Sea.
Haghighi Mood, Kaveh; Lüchow, Arne
2017-08-17
Diffusion quantum Monte Carlo calculations with partial and full optimization of the guide function are carried out for the dissociation of the FeS molecule. For the first time, quantum Monte Carlo orbital optimization for transition metal compounds is performed. It is demonstrated that energy optimization of the orbitals of a complete active space wave function in the presence of a Jastrow correlation function is required to obtain agreement with the experimental dissociation energy. Furthermore, it is shown that orbital optimization leads to a 5 Δ ground state, in agreement with experiments but in disagreement with other high-level ab initio wave function calculations which all predict a 5 Σ + ground state. The role of the Jastrow factor in DMC calculations with pseudopotentials is investigated. The results suggest that a large Jastrow factor may improve the DMC accuracy substantially at small additional cost.
Energy Technology Data Exchange (ETDEWEB)
Bertelli, N., E-mail: nbertell@pppl.gov; Gerhardt, S.; Hosea, J. C.; LeBlanc, B.; Perkins, R. J.; Phillips, C. K.; Taylor, G.; Valeo, E. J.; Wilson, J. R. [Princeton Plasma Physics Laboratory, Princeton, NJ 08543 (United States); Jaeger, E. F. [XCEL Engineering Inc., Oak Ridge, TN 37830 (United States); Lau, C.; Blazevski, D.; Green, D. L.; Berry, L.; Ryan, P. M. [Oak Ridge National Laboratory, Oak Ridge, TN 37831-6169 (United States); Bonoli, P. T.; Wright, J. C. [MIT Plasma Science and Fusion Center, Cambridge, MA 02139 (United States); Pinsker, R. I.; Prater, R. [General Atomics, PO Box 85608, San Diego, CA 92186-5608 (United States); Qin, C. M. [Institute of Plasma Physics, Chinese Academy of Sciences, Hefei 230031 (China); and others
2015-12-10
Several experiments on different machines and in different fast wave (FW) heating regimes, such as hydrogen minority heating and high harmonic fast waves, have found strong interactions between radio-frequency (RF) waves and the scrape-off layer (SOL) region. This paper examines the propagation and the power loss in the SOL by using the full wave code AORSA, in which the edge plasma beyond the last closed flux surface (LCFS) is included in the solution domain and a collisional damping parameter is used as a proxy to represent the real, and most likely nonlinear, damping processes. 3D AORSA results for the National Spherical Torus eXperiment (NSTX), where a full antenna spectrum is reconstructed, are shown, confirming the same behavior found for a single toroidal mode results in Bertelli et al, Nucl. Fusion, 54 083004, 2014, namely, a strong transition to higher SOL power losses (driven by the RF field) when the FW cut-off is moved away from in front of the antenna by increasing the edge density. Additionally, full wave simulations have been extended to “conventional” tokamaks with higher aspect ratios, such as the DIII-D, Alcator C-Mod, and EAST devices. DIII-D results show similar behavior found in NSTX and NSTX-U, consistent with previous DIII-D experimental observations. In contrast, a different behavior has been found for Alcator C-Mod and EAST, which operate in the minority heating regime unlike NSTX/NSTX-U and DIII-D, which operate in the mid/high harmonic regime. A substantial discussion of some of the main aspects, such as (i) the pitch angle of the magnetic field; (ii) minority heating vs. mid/high harmonic regimes is presented showing the different behavior of the RF field in the SOL region for NSTX-U scenarios with different plasma current. Finally, the preliminary results of the impact of the SOL region on the evaluation of the helicon current drive efficiency in DIII-D is presented for the first time and briefly compared with the different regimes
Full-Wave Analysis of Microstrip Antennas in Three-Layered Spherical Media
Directory of Open Access Journals (Sweden)
Tao Yu
2013-01-01
Full Text Available A model of three-layered spherical microstrip antenna has been analyzed based on Rao-Wilton-Glisson (RWG triangular basis functions using mixed potential integral equation (MPIE. Firstly, the model of antenna and the dyadic Green’s function in spherical microstrip antennas are given at the beginning of this paper. Then, due to the infinite series convergence problem, asymptotic extraction approach is presented to accelerate the Green’s functions convergence speed when source and field points are located in the same layer and different layers. The convergence speed can be accelerated observably by using this method. Finally, in order to simplify impedance matrix elements calculation at the junction of the probe and patch, a novel division fashion of pair of triangles is adopted in this paper. The input impedance result obtained shows the validity and effectiveness of the analysis method comparing with published data.
The International Celestial Reference Frame (ICRF) and the Relationship Between Frames
Ma, Chopo
2000-01-01
The International Celestial Reference Frame (ICRF), a catalog of VLBI source positions, is now the basis for astrometry and geodesy. Its construction and extension/maintenance will be discussed as well as the relationship of the ICRF, ITRF, and EOP/nutation.
Effect of energetic ion loss on ICRF heating efficiency and energy confinement time in heliotrons
International Nuclear Information System (INIS)
Murakami, S.; Nakajima, N.; Okamoto, M.; Nuehrenberg, J.
1999-06-01
ICRF heating efficiency and the global energy confinement time during ICRF heating are investigated including the effect of energetic ion loss in heliotrons. The approximate formula of ICRF heating efficiency is derived using the results based on Monte Carlo simulations. The global energy confinement time including energetic ion effect can be expressed in terms of ICRF heating power, plasma density, and magnetic field strength in heliotrons. Our results in the CHS plasma show the systematic decrement of the global energy confinement time due to the energetic ion loss from the assumed energy confinement scaling law, which is consistent with the experimental observations. Also we apply our model to the ICRF minority heating in the LHD plasma in two cases of typical magnetic configurations. The clear increment of the global energy confinement time due to the stored energy of energetic tail ions is obtained in the 'orbit improved' configuration, while the decrement is observed in the 'standard' configuration. (author)
Two-ion ICRF heating in Tokamaks
International Nuclear Information System (INIS)
Tennfors, E.
1985-03-01
The practical consequences for tokamak plasma heating in the ion cyclotron frequency regime of the two-dimensional treatment of the two-ion mode conversion layer are analyzed. The problem of evaluation of the condition for fast wave resonance is analyzed, as well as the limitations imposed by warm plasma effects. Simple ways to find the mode conversion surfaces when they exist are presented. Also for large tokamaks, it is possible to obtain mode conversion conditions for realistic antenna spectra provided species concentration and frequency are chosen such that the surface Epsilon = 0 intersects the plasma midplane just outside of the magnetic axis. (Author)
ICRF antenna Faraday shield plasma sheath model
International Nuclear Information System (INIS)
Whealton, J.H.; Ryan, P.M.; Raridon, R.J.
1990-01-01
A two-dimensional nonlinear formulation that explicitly considers the plasma edge near a Faraday shield in a self-consistent manner is used in the modeling of the ion motion for a Faraday shield concept and model suggested by Perkins. Two models are considered that may provide significant insight into the generation of impurities for ion cyclotron resonance heating (ICRH) antennas. In one of these models a significant sheath periodically forms next to the Faraday screen, with ion acoustic waves heating the ions in the plasma. (orig.)
Monaco, E.; Boffa, N. D.; Memmolo, V.; Ricci, F.; Maio, L.
2016-04-01
A full-scale lower wing panel made of composite material has been designed, manufactured and sensorised within the European Funded research project named SARISTU. The authors contributed to the whole development of the system, from design to implementation as well as to the impacts campaign phase where Barely Visible and Visible Damages (BVID and VID) are to be artificially induced on the panel by a pneumatic impact machine. This work summarise part of the experimental results related to damages production, their assessment by C-SCAN as reference NDT method as well as damage detection of delimitations by a guided waves based SHM. The SHM system is made by customized piezoelectric patches secondary bonded on the wing plate acting both as guided waves sources and receivers. The paper will deal mostly with the experimental impact campaign and the signal analyses carried out to extract the metrics more sensitive to damages induced. Image reconstruction of the damages dimensions and shapes will be also described based mostly on the combination of metrics maps over the plate partial surfaces. Finally a comparison of damages maps obtained by the SHM approach and those obtained by "classic" C-SCAN will be presented analyzing briefly pros and cons of the two different approached as a combination to the most effective structural maintenance scenario of a commercial aircraft.
Codina, R.; Ambrosini, D.
2018-03-01
For the last few decades, the effects of blast loading on structures have been studied by many researchers around the world. Explosions can be caused by events such as industrial accidents, military conflicts or terrorist attacks. Urban centers have been prone to various threats including car bombs, suicide attacks, and improvised explosive devices. Partially vented constructions subjected to external blast loading represent an important topic in protective engineering. The assessment of blast survivability inside structures and the development of design provisions with respect to internal elements require the study of the propagation and leakage of blast waves inside buildings. In this paper, full-scale tests are performed to study the effects of the leakage of blast waves inside a partially vented room that is subjected to different external blast loadings. The results obtained may be useful for proving the validity of different methods of calculation, both empirical and numerical. Moreover, the experimental results are compared with those computed using the empirical curves of the US Defense report/manual UFC 3-340. Finally, results of the dynamic response of the front masonry wall are presented in terms of accelerations and an iso-damage diagram.
The ASDEX Upgrade ICRF system: Operational experience and developments
International Nuclear Information System (INIS)
Faugel, H.; Angene, P.; Becker, W.; Braun, F.; Bobkov, Vl.V.; Eckert, B.; Fischer, F.; Hartmann, D.A.; Heilmaier, G.; Kneidl, J.; Noterdaeme, J.-M.; Siegl, G.; Wuersching, E.
2005-01-01
The ICRF system at the ASDEX Upgrade tokamak is in operation since May 1992. Following some modifications of which the major one was the installation of 3 dB couplers it has become a reliable additional heating system. The maximum power coupled into the plasma has been raised up to 7.2 MW (90% of the installed RF power) for short pulses and up to 6.2 MW for pulses several second long with energy of up to 29 MJ. A power of 5 MW is delivered on a regular basis to replace two NBI sources
ICRF array module development and optimization for high power density
International Nuclear Information System (INIS)
Ryan, P.M.; Swain, D.W.
1997-02-01
This report describes the analysis and optimization of the proposed International Thermonuclear Experimental Reactor (ITER) Antenna Array for the ion cyclotron range of frequencies (ICRF). The objectives of this effort were to: (1) minimize the applied radiofrequency rf voltages occurring in vacuum by proper layout and shape of components, limit the component's surface/volumes where the rf voltage is high; (2) study the effects of magnetic insulation, as applied to the current design; (3) provide electrical characteristics of the antenna for the development and analysis of tuning, arc detection/suppression, and systems for discriminating between arcs and edge-localized modes (ELMs); (4) maintain close interface with mechanical design
Improved confinement during ICRF heating on JFT-2M
International Nuclear Information System (INIS)
Matsumoto, Hiroshi; Ogawa, Toshihide; Tamai, Hiroshi
1986-10-01
Significant improvement of energy confinement was observed on JFT-2M during ICRF heating. This improvement is associated with the sudden depression of H α /D α emission and the following increase of plasma stored energy, electron density and the radiation loss. This should be the same phenomena as H-mode transitions observed in ASDEX, PDX, and D-III divertor experiments with neutral beam injection heating. However, this transition is also observed in limiter discharges as well as in open divertor configurations on JFT-2M. (author)
Effect on the Tritium Breeding Ratio due to a distributed ICRF antenna in a DEMO reactor
International Nuclear Information System (INIS)
Garcia, A.; Noterdaeme, J.-M.; Fischer, U.; Dies, J.
2016-01-01
This thesis reports results of MCNP-5 calculations, with the nuclear data library FENDL-2.1, to assess the effect on the Tritium Breeding Ratio (TBR) due to a distributed Ion Cyclotron Range of Frequencies (ICRF) antenna integrated in the blanket of a DEMO fusion power reactor. A preliminary design of the antenna with a reference configuration of the DEMO reactor was used together with a parametric analysis for different parameters that strongly affect the TBR. These are the type of breeding blanket (Helium Cooled Pebble Bed, Helium Cooled Lithium Lead and Water Cooled Lithium Lead), the covering ratio of the straps of the antenna (the ratio between the surface of all the straps and the projected surface of the antenna slot: 0.49, 0.72 and 0.94), the antenna radial thickness (20 cm and 40 cm), the thickness of the straps (2 cm, 4 cm and a double layer of 0.2 cm plus 2.5 cm with the composition of the First Wall), and finally the poloidal position of the antenna (0°, which is the equatorial port, 40° and 90°, which is the upper port). For an antenna with a full toroidal circumference of 360°, located poloidaly at 40° with a poloidal extension of 1 m and a total First Wall surface of 67 m"2, the reduction of the TBR is −0.35% for a HCPB blanket concept, −0.53% for a HCLL blanket concept and −0.51% for a WCLL blanket concept. In all cases covered by the parametric analysis, the loss of TBR remains below 0.61%. Such a distributed ICRF antenna has thus only a marginal effect on the TBR for a DEMO reactor.
Effect on the Tritium Breeding Ratio due to a distributed ICRF antenna in a DEMO reactor
Energy Technology Data Exchange (ETDEWEB)
Garcia, A., E-mail: albert.garcia.hp@gmail.com [Max-Planck-Institut für Plasmaphysik (IPP), Garching (Germany); Karlsruhe Institute of Technology (KIT), Karlsruhe (Germany); Polytechnic University of Catalonia (UPC), Barcelona (Spain); Department of Applied Physics, Ghent University, Ghent (Belgium); Noterdaeme, J.-M. [Max-Planck-Institut für Plasmaphysik (IPP), Garching (Germany); Department of Applied Physics, Ghent University, Ghent (Belgium); Fischer, U. [Karlsruhe Institute of Technology (KIT), Karlsruhe (Germany); Dies, J. [Polytechnic University of Catalonia (UPC), Barcelona (Spain)
2016-11-15
This thesis reports results of MCNP-5 calculations, with the nuclear data library FENDL-2.1, to assess the effect on the Tritium Breeding Ratio (TBR) due to a distributed Ion Cyclotron Range of Frequencies (ICRF) antenna integrated in the blanket of a DEMO fusion power reactor. A preliminary design of the antenna with a reference configuration of the DEMO reactor was used together with a parametric analysis for different parameters that strongly affect the TBR. These are the type of breeding blanket (Helium Cooled Pebble Bed, Helium Cooled Lithium Lead and Water Cooled Lithium Lead), the covering ratio of the straps of the antenna (the ratio between the surface of all the straps and the projected surface of the antenna slot: 0.49, 0.72 and 0.94), the antenna radial thickness (20 cm and 40 cm), the thickness of the straps (2 cm, 4 cm and a double layer of 0.2 cm plus 2.5 cm with the composition of the First Wall), and finally the poloidal position of the antenna (0°, which is the equatorial port, 40° and 90°, which is the upper port). For an antenna with a full toroidal circumference of 360°, located poloidaly at 40° with a poloidal extension of 1 m and a total First Wall surface of 67 m{sup 2}, the reduction of the TBR is −0.35% for a HCPB blanket concept, −0.53% for a HCLL blanket concept and −0.51% for a WCLL blanket concept. In all cases covered by the parametric analysis, the loss of TBR remains below 0.61%. Such a distributed ICRF antenna has thus only a marginal effect on the TBR for a DEMO reactor.
ICRF heating in JET during initial operations with the ITER-like wall
Energy Technology Data Exchange (ETDEWEB)
Jacquet, P.; Brix, M.; Graham, M.; Mayoral, M.-L.; Meigs, A.; Monakhov, I.; Sirinelli, A. [Euratom/CCFE Fusion Association, Culham Science Centre, Abingdon, OX14 3DB (United Kingdom); Bobkov, V.; Drewelow, P.; Pütterich, T. [Max-Planck-Institut für Plasmaphysik, EURATOM-Assoziation, Garching (Germany); Brezinsek, S. [IEK-4, Forschungszentrum Jülich, Association EURATOM-FZJ (Germany); Campergue, A-L. [Ecole Nationale des Ponts et Chaussées, F77455 Marne-la-Vallée (France); Colas, L. [CEA, IRFM, F-13108 Saint-Paul-Lez-Durance (France); Czarnecka, A. [Association Euratom-IPPLM, Hery 23, 01-497 Warsaw (Poland); Klepper, C. C. [Oak Ridge National Laboratory, Oak Ridge, TN 37831-6169 (United States); Lerche, E.; Van-Eester, D. [Association EURATOM-Belgian State, ERM-KMS, Brussels (Belgium); Milanesio, D. [Politecnico di Torino, Department of Electronics, Torino (Italy); Mlynar, J. [Association EURATOM-IPP.CR, Za Slovankou 3, 182 21 Praha 8 (Czech Republic); Collaboration: JET-EFDA Contributors
2014-02-12
In 2011/12, JET started operation with its new ITER-Like Wall (ILW) made of a tungsten (W) divertor and a beryllium (Be) main chamber wall. The impact of the new wall material on the JET Ion Cyclotron Resonance Frequency (ICRF) operation was assessed and also the properties of JET plasmas heated with ICRF were studied. No substantial change of the antenna coupling resistance was observed with the ILW as compared with the carbon wall. Heat-fluxes on the protecting limiters close the antennas quantified using Infra-Red (IR) thermography (maximum 4.5 MW/m{sup 2} in current drive phasing) are within the wall power load handling capabilities. A simple RF sheath rectification model using the antenna near-fields calculated with the TOPICA code can well reproduce the heat-flux pattern around the antennas. ICRF heating results in larger tungsten and nickel (Ni) contents in the plasma and in a larger core radiation when compared to Neutral Beam Injection (NBI) heating. Some experimental facts indicate that main-chamber W components could be an important impurity source: the divertor W influx deduced from spectroscopy is comparable when using RF or NBI at same power and comparable divertor conditions; the W content is also increased in ICRF-heated limiter plasmas; and Be evaporation in the main chamber results in a strong and long lasting reduction of the impurity level. The ICRF specific high-Z impurity content decreased when operating at higher plasma density and when increasing the hydrogen concentration from 5% to 20%. Despite the higher plasma bulk radiation, ICRF exhibited overall good plasma heating efficiency; The ICRF power can be deposited at plasma centre and the radiation is mainly from the outer part of the plasma. Application of ICRF heating in H-mode plasmas started, and the beneficial effect of ICRF central electron heating to prevent W accumulation in the plasma core could be observed.
International Celestial Reference Frame (ICRF): mantenimiento y extensión
Ma, C.; Arias, E. F.; Eubanks, T.; Fey, A. L.; Gontier, A.-M.; Jacobs, C. S.; Sovers, O. J.; Archinal, B. A.; Charlot, P.
A partir de enero de 1998 el sistema de referencia celeste convencional está representado por el International Celestial Reference System (ICRS) y materializado a través de las coordenadas VLBI del conjunto de radiofuentes extragalácticas que conforman el International Celestial Reference Frame (ICRF). La primera realización del ICRF, fue elaborada en 1995 por un grupo de expertos designado por la IAU, la que encomendó al International Earth Rotation Service el mantenimiento del ICRS, del ICRF y del vínculo con marcos de referencia en otras frecuencias. Una primera extensión del ICRF se realizó entre abril y junio de 1999, con el objetivo primario de proveer posiciones de radiofuentes extragalácticas observadas a partir de julio de 1995 y de mejorar las posiciones de las fuentes ``candidatas" con la inclusión de observaciones adicionales. Objetivos secundarios fueron monitorear a las radiofuentes para verificar que siguen siendo adecuadas para realizar al ICRF y mejorar las técnicas de análisis de datos. Como resultado del nuevo análisis se obtuvo una solución a partir de la cual se construyó la primera extensión del ICRF, denominada ICRF - Ext.1. Ella representa al ICRS, sus fuentes de definición se mantienen con las mismas posiciones y errores que en la primera realización del ICRF; las demás radiofuentes tienen coordenadas mejor determinadas que en ICRF; el marco de referencia se densificó con el agregado de 59 nuevas radiofuentes.
Heating profiles on ICRF antenna Faraday shields
International Nuclear Information System (INIS)
Taylor, D.J.; Baity, F.W.; Hahs, C.L.; Riemer, B.W.; Ryan, P.M.; Williamson, D.E.
1991-01-01
A conceptual design for an uncooled Faraday shield for the BPX ion cyclotron resonance heating (ICRH) antenna, which should withstand the proposed long-pulse operation, has been completed. A high-heat-flux, uncooled Faraday shield has also been designed for the fast-wave current drive (FWCD) antenna on D3-D. For both components, the improved understanding of the heating profiles made it possible to design for heat fluxes that would otherwise have been too close to mechanically established limits. The analytical effort is described in detail, with emphasis on the design work for the BPX ICRH antenna conceptual design and for the replacement Faraday shield for the D3-D FWCD antenna. Results of analyses are shown, and configuration issues involved in component modeling are discussed. 3 refs., 6 figs., 2 tabs
The effect of ICRF antenna phasing on metal impurities in TFTR
International Nuclear Information System (INIS)
Stevens, J.E.; Bush, C.; Colestock, P.L.; Oak Ridge National Lab., TN; AN Ukrainskoj SSR, Kharkov
1989-07-01
ICRF power levels of up to 2.8 MW were achieved during the 1988 experimental run on TFTR. Metal impurity concentrations (Ti, Cr, Fe, Ni) and Z eff were monitored during ICRF heating by x-ray pulse height analysis and uv spectroscopy. Antenna phasing was the key variable affecting ICRF performance. No increase in metallic impurities was observed for P rf approx lt 2.8 MW with the antenna straps 0-Π, while a measurable increase in titanium (Faraday screen material) was observed for P rf approx gt 1.0 MW with 0-0 phasing. 18 refs., 8 figs
Heat loads on Tore Supra ICRF Launchers Plasma Facing Components
International Nuclear Information System (INIS)
Bremond, S.; Colas, L.; Beaumont, B.; Chantant, M.; Goniche, M.; Mitteau, R.
2005-01-01
Understanding the heat loads on Ion Cyclotron Range of Frequency (ICRF) launchers plasma-facing components is a crucial task both for operating present tokamaks and for designing ITER ICRF launchers as these loads may limit the RF power coupling capability. Tore Supra facility is particularly well suited to take this issue. Parametric studies have been performed which enables to get an overall detailed picture of the different heat loads on several areas, pointing to different mechanisms at the origin of the heat power fluxes. It is found that the most critical items for Tore-Supra operation are localized heat loads on the Faraday screen top left corner and vertical edges. Warming up close to maximum temperature limit originally set for protection of the plasma-facing components is found of high power pulses, but no erosion was observed after detailed inspection of the launcher in Tore-Supra vessel. Yet, the associated heat loads could be limiting for Tore-Supra operation in the future, and some dedicated work is under progress to improve the understanding of these power fluxes, pointing out the importance of getting a better knowledge of particle flows in the scrape of layer
Foundations of ICRF heating--A historical perspective
International Nuclear Information System (INIS)
Hosea, J.C.
1994-01-01
Tom Stix has made many major contributions to the development of understanding of a wide array of rf heating and diagnostics methods, in experiment and theory. In recognition of his profound influence on ion cyclotron range of frequencies (ICRF) heating research, this paper is focused on two major building blocks contributed by him which served to help guide and quantify the research toward establishing ICRF heating as a viable technique for the reactor regime: (1) the formalism for quantitative evaluation of antenna loading contained in his 1962 text book and (2) his Fokker-Planck analysis for heating of ions and especially minority species ions in his 1975 Nuclear Fusion paper. Importantly, his work from the mid 1950s to the mid 1970s from which these two building blocks derive, provided a solid basis for the rapid developing ion cyclotron heating research in the 1970s and helped to guide that research to definitive demonstration of the viability of the minority ion heating regime as a reactor heating method by the end of the decade
Arc detection for the ICRF system on ITER
D'Inca, R.
2011-12-01
The ICRF system for ITER is designed to respect the high voltage breakdown limits. However arcs can still statistically happen and must be quickly detected and suppressed by shutting the RF power down. For the conception of a reliable and efficient detector, the analysis of the mechanism of arcs is necessary to find their unique signature. Numerous systems have been conceived to address the issues of arc detection. VSWR-based detectors, RF noise detectors, sound detectors, optical detectors, S-matrix based detectors. Until now, none of them has succeeded in demonstrating the fulfillment of all requirements and the studies for ITER now follow three directions: improvement of the existing concepts to fix their flaws, development of new theoretically fully compliant detectors (like the GUIDAR) and combination of several detectors to benefit from the advantages of each of them. Together with the physical and engineering challenges, the development of an arc detection system for ITER raises methodological concerns to extrapolate the results from basic experiments and present machines to the ITER scale ICRF system and to conduct a relevant risk analysis.
International Nuclear Information System (INIS)
Shad-Manamen, N.; Eskandari-Ghadi, M.
2008-01-01
The existing theory for wave propagation through a soil layer are not compatible with the real soil layers because in the theory the layers are flat and the sub-layers are parallel, while in real the soil layers are not flat and they may not be parallel. Thus, wave propagations through a corrugated interface are so important. In this paper, a two dimensional SH-wave propagation through a corrugated interface between two linear transversely isotropic half-spaces is assessed. In order to do this, Lord Rayleigh's method is accepted to express the non-flat surface by a Fourier series. In this way, the amplitude of the reflected and transmitted waves is analytically determined in terms of the incident SH-wave amplitude. It is shown that except for the regular reflected and refracted waves, some irregular reflected and refracted waves are exist, and the amplitudes of these waves vary in terms of the angle and frequency of incident wave, equation of surface, and the material properties of the domains. The numerical computations for some cases of different amplitude/wave-length ratio of the interface are done. This work is an extension of Asano's paper (1960) for a more complicated interface, where more non-zero coefficients are considered in expressing the equation of surface in the form of Fourier series. The analytical results for some simpler case of isotropic domain are collapsed on Asano's results (1960). In addition, the numerical evaluation is in good agreement with Asano's.
Schumacher, F.; Friederich, W.
2015-12-01
We present the modularized software package ASKI which is a flexible and extendable toolbox for seismic full waveform inversion (FWI) as well as sensitivity or resolution analysis operating on the sensitivity matrix. It utilizes established wave propagation codes for solving the forward problem and offers an alternative to the monolithic, unflexible and hard-to-modify codes that have typically been written for solving inverse problems. It is available under the GPL at www.rub.de/aski. The Gauss-Newton FWI method for 3D-heterogeneous elastic earth models is based on waveform sensitivity kernels and can be applied to inverse problems at various spatial scales in both Cartesian and spherical geometries. The kernels are derived in the frequency domain from Born scattering theory as the Fréchet derivatives of linearized full waveform data functionals, quantifying the influence of elastic earth model parameters on the particular waveform data values. As an important innovation, we keep two independent spatial descriptions of the earth model - one for solving the forward problem and one representing the inverted model updates. Thereby we account for the independent needs of spatial model resolution of forward and inverse problem, respectively. Due to pre-integration of the kernels over the (in general much coarser) inversion grid, storage requirements for the sensitivity kernels are dramatically reduced.ASKI can be flexibly extended to other forward codes by providing it with specific interface routines that contain knowledge about forward code-specific file formats and auxiliary information provided by the new forward code. In order to sustain flexibility, the ASKI tools must communicate via file output/input, thus large storage capacities need to be accessible in a convenient way. Storing the complete sensitivity matrix to file, however, permits the scientist full manual control over each step in a customized procedure of sensitivity/resolution analysis and full
Electromagnetic simulations of the ASDEX Upgrade ICRF Antenna with the TOPICA code
International Nuclear Information System (INIS)
Krivska, A.; Milanesio, D.; Bobkov, V.; Braun, F.; Noterdaeme, J.-M.
2009-01-01
Accurate and efficient simulation tools are necessary to optimize the ICRF antenna design for a set of operational conditions. The TOPICA code was developed for performance prediction and for the analysis of ICRF antenna systems in the presence of plasma, given realistic antenna geometries. Fully 3D antenna geometries can be adopted in TOPICA, just as in available commercial codes. But while those commercial codes cannot operate with a plasma loading, the TOPICA code correctly accounts for realistic plasma loading conditions, by means of the coupling with 1D FELICE code. This paper presents the evaluation of the electric current distribution on the structure, of the parallel electric field in the region between the straps and the plasma and the computation of sheaths driving RF potentials. Results of TOPICA simulations will help to optimize and re-design the ICRF ASDEX Upgrade antenna in order to reduce tungsten (W) sputtering attributed to the rectified sheath effect during ICRF operation.
Removal of particles by ICRF cleaning in HT-7 superconducting tokamak
International Nuclear Information System (INIS)
Hu Jiansheng; Li Jiangang; Zhang Shouyin; Gu Xuemao; Zhang Xiaodong; Zhao Yanping; Gong Xianzu; Kuang Guangli; Li Chengfu; Luo Jiarong; Wang Xiaoming; Gao Xiang; Wan Baonian; Xie Jikang; Wan Yuanxi
2001-01-01
The ICRF (Ion Cyclotron Range Frequency) cleaning technique has been used as a routine wall cleaning method in the HT-7 superconducting tokamak. In a wide range of toroidal field, the removal rate of residual gas by ICRF cleaning was about twenty times higher than that of glow discharge cleaning (GDC). At different gas pressure and RF power levels, the ICRF cleaning is studied carefully. A good impurity cleaning effect and a very high hydrogen removal rate were obtained. The removal rate of hydrogen by 5 kW ICRF cleaning achieved was 1.6 x 10 -5 Torr.l/s. And the relationships among pressure P, outgassing rate Q, atomic layers L absorbed on surface and the cleaning mode were discussed briefly
Measurement of fast minority /sub 3/He/sup + +/ energy distribution during ICRF heating
Post, D.E. Jr.; Grisham, L.R.; Medley, S.S.
A method and means for measuring the fast /sub 3/He/sup + +/ distribution during /sub 3/He/sup + +/ minority Ion Cyclotron Resonance Frequency (ICRF) heating is disclosed. The present invention involves the use of 10 to 100 keV beams of neutral helium atoms to neutralize the fast /sub 3/He/sup + +/ ions in a heated plasma by double charge exchange (/sub 3/He/sup + +/ + /sub 4/He/sup 0/ ..-->.. /sub 3/He/sup 0/ + /sub 4/He/sup + +/). The neutralized fast /sub 3/He/sup 0/ atoms then escape from the hot plasma confined by a magnetic field and are detected by conventional neutral particle analyzing means. This technique permits the effectiveness of the coupling of the ion cyclotron waves to the /sub 3/He/sup + +/ minority ions to be accurately measured. The present invention is particularly adapted for use in evaluating the effectiveness of the intermediate coupling between the RF heating and the /sub 3/He/sup + +/ in an energetic toroidal plasma.
Construction of a resonant loop with the ICRF antenna for KSTAR
International Nuclear Information System (INIS)
Bae, Young Dug; Jeong, Sung Un; Yoon, Jae Sung; Hong, Bong Geon
2003-01-01
The antenna of the KSTAR ICRF heating system consists of four current straps, each of which is grounded at the center, and has two coaxial ports, one at each end. The top and bottom ports of each strap are fed by one transmitter. The two ports are connected at tee connector to form a resonant loop, and the coaxial feed line from the transmitter is connected to the tee. One resonant loop with the proto-type antenna is built at the RF test stand in KAERI. It is composed with one current strap, one tee connector and two arms connecting them. Each arm consists of a 6-inch vacuum transmission line, a vacuum feed through, a part of pressurized 9-inch coaxial line, and an adjustable phase shifter to cover wide frequency range of 25-60 MHz. Total electrical length is changeable from 45 to 51 m. Many voltage probes and directional couplers are installed to measure RF voltage of the standing wave, power flow and phase difference. Resonant and matching conditions are investigated for various frequencies
Analysis of an inverter-supplied multi-winding transformer with a full-wave rectifier at the output
International Nuclear Information System (INIS)
Klopcic, Beno; Dolinar, Drago; Stumberger, Gorazd
2008-01-01
This paper deals with the magnetic analysis of an inverter-supplied multi-winding transformer frequently used in resistance spot welding applications. The basic structure of the analyzed system consists of an inverter, a single-phase transformer with two secondary windings and a full-wave rectifier mounted at the output of the transformer, which assure a very short rise time of the welding current. The disturbing current spikes often appear in the transformer's primary in the steady-state operation, which can activate the over-current protection switch-off of the system. The results of numerical analysis performed on the nonlinear model of the discussed system have shown that very strong magnetic saturation of the transformer's iron core, caused by the interaction among the different ohmic resistances of secondary windings and different characteristics of the output rectifier diodes, provokes unwanted current spikes. Magnetic saturation could be efficiently eliminated using very simple passive method proposed in this paper. All findings are confirmed by systematic analysis numerically and experimentally
ICRF heating and transport of deuterium-tritium plasmas in TFTR
International Nuclear Information System (INIS)
Rogers, J.H.; Schilling, G.; Stevens, J.E.; Taylor, G.; Wilson, J.R.; Bell, M.G.; Budny, R.V.; Bretz, N.L.; Darrow, D.; Fredrickson, E.
1995-02-01
This paper describes results of the first experiments utilizing high-power ion cyclotron range of frequency (ICRF) to heat deuterium-tritium (D-T) plasmas in reactor-relevant regimes on the Tokamak Fusion Test Reactor (TFTR). Results from these experiments have demonstrated efficient core, second harmonic, tritium beating of D-T supershot plasmas with tritium concentrations ranging from 6%-40%. Significant direct ion heating on the order of 60% of the input radio frequency (rf) power has been observed. The measured deposition profiles are in good agreement with two-dimensional modeling code predictions. Energy confinement in an rf-heated supershot is at least similar to that without rf, and possibly better in the electron channel. Efficient electron heating via mode conversion of fast waves to ion Bernstein waves (IBW) has been demonstrated in ohmic, deuterium-deuterium and DT-neutral beam injection plasmas with high concentrations of minority 3 He (n 3He /n e = 15% - 30%). By changing the 3 He concentration or the toroidal field strength, the location of the mode-conversion radius was varied. The power deposition profile measured with rf power modulation indicated that up to 70% of the power can be deposited on electrons at an off-axis position. Preliminary results with up to 4 MW coupled into the plasma by 90-degree phased antennas showed directional propagation of the mode-converted IBW. Analysis of heat wave propagation showed no strong inward thermal pinch in off-axis heating of an ohmically-heated target plasma in TFTR
ICRF heating and transport of deuterium-tritium plasmas in TFTR
International Nuclear Information System (INIS)
Murakami, M.; Batchelor, D.B.; Bush, C.E.
1994-01-01
This paper describes results of the first experiments utilizing high-power ion cyclotron range of frequency (ICRF) to heat deuterium-tritium (D-T) plasmas in reactor-relevant regimes on the Tokamak Fusion Test Reactor (TFTR). Results from these experiments have demonstrated efficient core, second harmonic, tritium heating of D-T supershot plasmas with tritium concentrations ranging from 6%--40%. Significant direct ion heating on the order of 60% of the input radio frequency (rf) power has been observed. The measured deposition profiles are in good agreement with two-dimensional modeling code predictions. Confinement in an rf-heated supershot is at least similar to that without rf, and possibly better in the electron channel. Efficient electron heating via mode conversion of fast waves to ion Bernstein waves (IBW) has been demonstrated in ohmic, deuterium-deuterium and DT-neutral beam injection plasmas with high concentrations of minority 3 He (n 3 He /n e > 10%). By changing the 3 He concentration or the toroidal field strength, the location of the mode-conversion radius was varied. The power deposition profile measured with rf power modulation showed that up to 70% of the power can be deposited on electrons at an off-axis position. Preliminary results with up to 4 MW coupled into the plasma by 90-degree phased antennas showed directional propagation of the mode-converted IBW. Heat wave propagation showed no strong inward thermal pinch in off-axis heating of an ohmically-heated (OH) target plasma in TFIR
Kang, S. G.; Hong, J. K.; Jin, Y. K.; Jang, U.; Niessen, F.; Baranov, B.
2017-12-01
2016 IBRV ARAON Arctic Cruise Leg-2, Expedition ARA07C was a multidisciplinary undertaking carried out in the East Siberian Sea (ESS) from August 25 to September 10, 2016. The program was conducted as a collaboration between the Korea Polar Research Institute (KOPRI), P.P. Shirshov Institute of Oceanology (IORAS), and Alfred Wegener Institute (AWI). During this expedition, the multi-channel seismic (MCS) data were acquired on the continental shelf and the upper slope of the ESS, totaling 3 lines with 660 line-kilometers. The continental shelf of ESS is one of the widest shelf seas in the world and it is believed to cover the largest area of sub-sea permafrost in the Arctic. According to the present knowledge of the glacial history of the western Arctic Ocean, it is likely that during the LGM with a sea level approximately 120 m below present, the entire shelf area of the ESS was exposed to very cold air temperatures so that thick permafrost should have formed. Indeed, in water depths shallower than 80 m, sub-bottom profiles in the ESS recorded from the shelf edge to a latitude of 74°30' N in 60 m water depth exhibited acoustic facies, suggesting that at least relicts of submarine permafrost are present. In order to identify the existence and/or non-existence of subsea permafrost in our study area, we analyze the MCS data using the Laplace domain full waveform inversion (FWI). In case of the Canadian continental shelf of the Beaufort Sea, subsea permafrost has high seismic velocity values (over 2.6 km/sec) and strong refraction events were found in the MCS shotgathers. However, in the EES our proposed P-wave velocity models derived from FWI have neither found high velocity structures (over 2.6 km/sec) nor indicate strong refraction events by subsea permafrost. Instead, in 300 m depth below sea floor higher P-wave velocity structures (1.8 2.2 km/s) than normal subsea sediment layers were found, which are interpreted as cemented strata by glaciation activities.
International Nuclear Information System (INIS)
Fujii, Tsuneyuki
1992-03-01
Two main subjects of ion cyclotron range of frequencies (ICRF) heating on JT-60 are described in this paper from development phase of the JT-60 ICRF heating system up to advanced experiment I, 1989. One is antenna design and development for the high power JT-60 ICRF heating system (6 MW for 10 s at a frequency range of 108 - 132 MHz). The other is the experimental investigation of characteristics of second harmonic ICRF heating in a large tokamak. (J.P.N.)
High coupling performance of JT-60U ICRF antennas
International Nuclear Information System (INIS)
Saigusa, M.; Moriyama, S.; Fujii, T.; Kimura, H.; Sato, M.; Hosogane, N.; Nemoto, M.; Yamamoto, T.
1994-01-01
Sufficient coupling of an ICRF antenna for high power experiments was obtained even for a wide gap between the separatrix and the antenna in JT-60U. The loading resistances for an out-of-phase mode are over 4 Ω for a gap of 13 cm between the separatrix and the Faraday shield over the wide range of electron density from 1 x 10 19 to 5.5 x 10 19 m -3 . In particular, the loading resistances for an in-phase mode are about 5 Ω for a gap of 33 cm between the separatrix and the Faraday shield for the same plasma parameters. However, the heating response for the out-of phase mode is much stronger than that for the in-phase mode. (author). Letter-to-the-editor. 11 refs, 6 figs
A predictive transport modeling code for ICRF-heated tokamaks
International Nuclear Information System (INIS)
Phillips, C.K.; Hwang, D.Q.
1992-02-01
In this report, a detailed description of the physic included in the WHIST/RAZE package as well as a few illustrative examples of the capabilities of the package will be presented. An in depth analysis of ICRF heating experiments using WHIST/RAZE will be discussed in a forthcoming report. A general overview of philosophy behind the structure of the WHIST/RAZE package, a summary of the features of the WHIST code, and a description of the interface to the RAZE subroutines are presented in section 2 of this report. Details of the physics contained in the RAZE code are examined in section 3. Sample results from the package follow in section 4, with concluding remarks and a discussion of possible improvements to the package discussed in section 5
DIII-D ICRF high voltage power supply regulator upgrade
International Nuclear Information System (INIS)
Cary, W.P.; Burley, B.L.; Grosnickle, W.H.
1997-11-01
For reliable operation and component protection, of the 2 MW 30--120 MHz ICRF Amplifier System on DIII-D, it is desirable for the amplifier to respond to high VSWR conditions as rapidly as possible. This requires a rapid change in power which also means a rapid change in the high voltage power supply current demands. An analysis of the power supply's regulator dynamics was needed to verify its expected operation during such conditions. Based on this information it was found that a new regulator with a larger dynamic range and some anticipation capability would be required. This paper will discuss the system requirements, the as-delivered regulator performance, and the improved performance after installation of the new regulator system. It will also be shown how this improvement has made the amplifier perform at higher power levels more reliably
Generation and Sustainment of Plasma Rotation by ICRF Heating
Perkins, F. W.
2000-10-01
When tokamak plasmas are heated by the fundamental minority ion-cyclotron process, they are observed to rotate toroidally, even though this heating process introduces negligable angular momentum. This work proposes and evaluates a physics mechanism which resolves this apparent conflict. The argument has two elements. First, it is assumed that angular momentum transport is governed by a diffusion equation with a v_tor = 0 boundary condition at the plasma surface and a torque-density source. When the source consists of separated regions of positive and negative torque density, a finite central rotation velocity results, even though the volume integrated torque density - the angular momentum input - vanishes. Secondly, ions energized by the ICRF process can generate separated regions of positive and negative torque density. Heating increases their banana widths which leads to radial energetic-particle transport that must be balanced by neutralizing radial currents and a j_rB_pR torque density in the bulk plasma. Additional, comparable torque density results from collisional transfer of mechanical angular momentum from energetic particles to the bulk plasma and particle loss through banana particles impacting the wall. Monte-Carlo calculations utilizing the ORBIT code evaluate all sources of torque density and rigorously assure that no net angular momentum is introduced. Two models of ICRF heating, diffusive and instantaneous, give similar results. When the resonance location is on the LFS, the calculated rotation has the magnitude, profile, and co-current sense of Alcator C-Mod observations. For HFS resonance locations, the model predicts counter-current rotation. Scans of rotational profiles vs. resonance location, initial energy, particle loss, pitch, and qm will be presented as will the location of the velocity shear layer its scaling to a reactor.
Design of optimized impedance transformer for ICRF antenna in LHD
Energy Technology Data Exchange (ETDEWEB)
Saito, K., E-mail: saito@nifs.ac.jp [National Institute for Fusion Science, Toki, Gifu, 509-5292 (Japan); Seki, T.; Kasahara, H.; Seki, R.; Kumazawa, R.; Nomura, G.; Shimpo, F.; Mutoh, T. [National Institute for Fusion Science, Toki, Gifu, 509-5292 (Japan)
2013-10-15
Highlights: ► We developed optimization method of impedance transformer for ICRF antenna. ► Power loss will be one-third with the optimized impedance transformer. ► Possibility of damage on the transmission line will be drastically reduced. ► High performance will be kept in the wide antenna impedance region. -- Abstract: A pair of ion cyclotron range of frequencies (ICRF) antennas in the large helical device (LHD), HAS antennas showed high efficiency in minority ion heating. However the low loading resistance must be increased to prevent breakdown in transmission line. Moreover, the voltage and the current around the feed-through must be reduced to protect it. For these purpose, we developed a design procedure of the impedance transformer for HAS antennas. To optimize the transformer, the inner conductors were divided into several segments and the radii of them were given discretely and independently. The maximum effective loading resistance was obtained by using all combinations of radii within the limitations of the voltage and current at the feed-through and the electric field on the transformer. To get a precise solution, this procedure was repeated several times by narrowing the range of radii of inner conductors. Then the optimized impedance transformer was designed by smoothing the radii of inner conductors. For the typical discharge, the voltage and current at the feed-through were reduced to the half of the original values with the same power. The effective loading resistance was increased to more than four times. High performance is expected in wide impedance region.
De Coster, Albéric; Phuong Tran, Anh; Lambot, Sébastien
2014-05-01
Water lost through leaks can represent high percentages of the total production in water supply systems and constitutes an important issue. Leak detection can be tackled with various techniques such as the ground-penetrating radar (GPR). Based on this technology, various procedures have been elaborated to characterize a leak and its evolution. In this study, we focus on a new full-wave radar modelling approach for near-field conditions, which takes into account the antenna effects as well as the interactions between the antenna(s) and the medium through frequency-dependent global transmission and reflection coefficients. This approach is applied to layered media for which 3-D Green's functions can be calculated. The model allows for a quantitative estimation of the properties of multilayered media by using full-wave inversion. This method, however, proves to be limited to provide users with an on-demand assessment as it is generally computationally demanding and time consuming, depending on the medium configuration as well as the number of unknown parameters to retrieve. In that respect, we propose two leads in order to enhance the parameter retrieval step. The first one consists in analyzing the impact of the reduction of the number of frequencies on the information content. For both numerical and laboratory experiments, this operation has been achieved by investigating the response surface topography of objective functions arising from the comparison between measured and modelled data. The second one involves the numerical implementation of multistatic antenna configurations with constant and variable offsets in the model. These two kinds of analyses are then combined in numerical experiments to observe the conjugated effect of the number of frequencies and the offset configuration. To perform the numerical analyses, synthetic Green's functions were simulated for different multilayered medium configurations. The results show that an antenna offset increase leads
Haikonen, Kalle; Sundberg, Jan; Leijon, Mats
2013-01-01
Wave energy conversion is a clean electric power production technology. During operation there are no emissions in the form of harmful gases. However there are unsolved issues considering environmental impacts such as: electromagnetism; the artificial reef effect and underwater noise. Anthropogenic noise is increasing in the oceans worldwide and wave power will contribute to this sound pollution in the oceans; but to what extent? The main purpose of this study was to examine the noise emitted...
International Nuclear Information System (INIS)
Yang Cheng; Zhu Sizheng; Zhang Xinjun
2010-01-01
Simulation on the heating scenarios in experimental advanced superconducting tokamak (EAST) was performed by using a full wave code TORIC. The locations of resonance layers for these heating schemes are predicted and the simulations for different schemes in ICRF experiments in EAST, for example, ion heating (both fundamental and harmonic frequency) or electron heating (by direct fast waves or by mode conversion waves), on-axis or off-axis heating, and high-field-side (HFS) launching or low-field-side (LFS) launching, etc, were conducted. For the on-axis minority ion heating of 3 He in D( 3 He) plasma, the impacts of both density and temperature on heating were discussed in the EAST parameter ranges.
Mengxuan, Zhong
2017-06-01
The gradient preconditioning algorithms based on Hessian matrices in time-domain full waveform inversion (FWI) are widely used now, but consume a lot of memory and do not fit the FWI of large models or actual seismic data well. To avoid the huge storage consumption, the gradient preconditioning approach based on seismic wave energy has been proposed it simulates the “approximated wave field” with the acoustic wave equation and uses the energy of the simulated wavefield to precondition the gradient. The method does not require computing and storing the Hessian matrix or its inverse and can effectively eliminate the effect caused by geometric diffusion and uneven illumination on gradient. The result of experiments in this article with field data from South China Sea confirms that the time-domain FWI using the gradient preconditioning based on seismic wave energy (GPWE) can achieve higher inversion accuracy for the deep high-velocity model and its underlying strata.
DEFF Research Database (Denmark)
Koukoura, Christina; Brown, Cameron; Natarajan, Anand
2016-01-01
Wind–wave misalignment is often necessary to consider during the design of offshore wind turbines due to excitation of side–side vibration and the low aerodynamic damping in that direction. The measurements from a fully instrumented 3.6 MW pitch regulated-variable speed offshore wind turbine were...
Effect of energetic ion loss on ICRF heating efficiency and energy confinement time in heliotrons
International Nuclear Information System (INIS)
Murakami, S.; Nakajima, N.; Okamoto, M.; Nuehrenberg, J.
1999-01-01
The ICRF heating efficiency and the global energy confinement time during ICRF heating are investigated, including the effect of energetic ion loss in heliotrons. The approximate formula of ICRF heating efficiency is derived using results based on Monte Carlo simulations (Murakami, S., et al., Fusion Eng. Des. 26 (1995) 209). The global energy confinement time including the energetic ion effect can be expressed in heliotrons in terms of ICRF heating power, plasma density and magnetic field strength. Results in plasmas at CHS show a systematic decrease of the global energy confinement time due to energetic ion loss from the assumed energy confinement scaling law, which is consistent with the experimental observations. The model is also applied to ICRF minority heating in LHD plasmas in two cases of typical magnetic configurations. A clear increase of the global energy confinement time due to the stored energy of energetic tail ions is obtained in the 'orbit improved' configuration, while a decrease is observed in the 'standard' configuration. (author)
International Nuclear Information System (INIS)
Fraboulet, D.; Becoulet, A.; Nguyen, F.
1998-11-01
To maintain the ignition state in a tokamak fusion reactor, a control must be performed on the population of alpha-products, and this implies the ability to diagnose those α-particles. It is studied here whether the detection of emission radiated in the ion cyclotron range of frequency be a reactor plasma can provide useful information concerning fusion products, especially concerning their density profile. It is shown that the detection of the radiation emitted by the fast alpha particles along their cyclotron motion can give access to moments of their distribution function. This requires to compute the phase of the emitted field, using a full-wave approach. Such a technique allows to set in a convenient way the inverse problem of the determination of the emitting α-particles distribution through the radiation detection. A brief analysis of the expected situation in a reactor-relevant plasma is given. In parallel, the 1-D full-wave code developed in this frame is also useful for studying the physics of Fast Wave plasma heating. It enables to take into account the mode conversion of the Fast Wave into the Ion Bernstein Wave that appears near each ion cyclotron resonance. Results show that higher order terms may significantly alter the energy partitioning, in hot plasma cases involving mode conversion heating and/or ion cyclotron high harmonics heating. (author)
Wang, Yiqun; Pei, Li; Li, Jing; Li, Yueqin
2017-06-10
A full-duplex radio-over-fiber system is proposed, which provides both the generation of a millimeter-wave (mm-wave) signal with tunable frequency multiplication factors (FMFs) and wavelength reuse for uplink data. A dual-driving Mach-Zehnder modulator and a phase modulator are cascaded to form an optical frequency comb. An acousto-optic tunable filter based on a uniform fiber Bragg grating (FBG-AOTF) is employed to select three target optical sidebands. Two symmetrical sidebands are chosen to generate mm waves with tunable FMFs up to 16, which can be adjusted by changing the frequency of the applied acoustic wave. The optical carrier is reused at the base station for uplink connection. FBG-AOTFs driven by two acoustic wave signals are experimentally fabricated and further applied in the proposed scheme. Results of the research indicate that the 2-Gbit/s data can be successfully transmitted over a 25-km single-mode fiber for bidirectional full-duplex channels with power penalty of less than 2.6 dB. The feasibility of the proposed scheme is verified by detailed simulations and partial experiments.
Lead elimination by ICRF 158 in rats after chronic lead exposure
Energy Technology Data Exchange (ETDEWEB)
Witting, U; Hultsch, E
1981-02-01
Lead elimination by ICRF 158, a lipophilic derivative of ethylene-diaminetetra-acetate (EDTA), was investigated in rats after chronic lead exposure. The animals had received a lead concentration of 550 ppm in their drinking water for 140 days. Subsequent treatment with ICRF 158 for 30 days led to increased mobilization and elimination of incorporated lead, and the lead-induced inhibition of hemosynthesis was removed. ICR 158 produced no renal damage in excess to lead-induced tubular nephrosis. Separate toxicity tests in mice demonstrated that is less toxic than CaNa/sub 2/EDTA. ICRF 158 does not form stable complexes with lead ions in vitro. The mechanism of action of this lipophilic EDTA derivative is compared to that of its hydrophilic correspondent, the chelating agent CaNa/sub 2/EDTA.
Rf sheaths and impurity generation by ICRF [ion cyclotron range of frequencies] antennas
International Nuclear Information System (INIS)
Perkins, F.W.
1988-11-01
In general, Faraday screen elements in an ICRF antenna are not aligned precisely along the combined toroidal and poloidal magnetic fields. When plasma of density n > 2ε 0 V/eg 2 /approximately/ 10 9 cm -3 is present in the gap between elements, electron response to the parallel electric field shorts out the electric field over most of the gap, leaving a narrow sheath of positive space charge and intense electric field. Here V denotes the voltage across the gap and g the gap spacing. This intense electric field accelerates ions up to an appreciable fraction of the gap voltage (/approximately/ 1 kV), sufficient to cause physical sputtering of the screen material. Impurities so generated constitute the principal limitation on power density (kW/cm 2 ) for ICRF antennas. ICRF antenna and Faraday screen design principles which minimize sputtering are discussed. 24 refs., 9 figs., 1 tab
International Nuclear Information System (INIS)
Kumazawa, R.; Saito, K.; Kasahara, H.; Seki, T.; Mutoh, T.; Shimpo, F.; Nomura, G.; Kato, A.; Okada, H.; Zhao, Y.; Kwak, J.G.; Yoon, J.S.
2008-01-01
Ion cyclotron range of frequency (ICRF) heating has been a reliable tool for steady-state plasma heating with high RF power of several tens of megawatts. However, a sudden increase in the reflected RF power during ICRF heating experiments with ELMy H-mode plasmas is an issue which must be solved for future fusion experimental devices or fusion reactors. This paper describes an innovative ICRF heating system using a frequency feedback control to reduce the reflected power in response to the rapid change in the plasma impedance in the ELMy H-mode plasma. A twin stub tuner has been newly invented for this purpose. The feasibility of keeping the reflected RF power fraction at a low level, e.g. 1%, is demonstrated even with a large change in plasma resistance, e.g. 2 ∼ 8Ω. Calculated and experimental results are presented for the conventional double stub tuner impedance matching system equipped with the twin stub tuner.
ICRF heating of passing ions in a thermal barrier tandem mirror
International Nuclear Information System (INIS)
Molvik, A.W.; Dimonte, G.; Campbell, R.; Barter, J.; Cummins, W.F.; Falabella, S.; Poulsen, P.
1985-05-01
Ion heating is used in the central cells of tandem mirrors to reduce the collisional trapping of passing ions in the end cell thermal barriers. In this paper, we reevaluate ICRF heating of the TMX-U central cell in two limits. The first we term isotropic, because we impose the condition that ions heated in the perpendicular direction be confined for at least one 90 0 scattering time, thereby heating the passing ions. The second we call anisotropic heating. It uses higher ICRF power to mirror trap a majority of the ions near the midplane, thereby reducing the density and collisionality of passing ions. Anisotropic heating has the advantage of increasing with ICRF power, whereas isotropic heating is limited by ion collisionality. Both techniques require gas fueling near the central cell midplane, with an ion cyclotron resonance toward each end cell to heat the cold ions
International Nuclear Information System (INIS)
Burma, C.; Cuperman, S.; Komoshvili, K.
1998-01-01
The wave equation for strongly toroidal small aspect ratio (spherical) tokamaks with non-circular cross-section is properly formulated and solved for global waves, in the Alfven frequency range. The current-carrying toroidal plasma is surrounded by a helical sheet-current antenna, which is enclosed within a perfectly conducting wall. The problem is formulated in terms of the vector and scalar potentials (A,Φ), thus avoiding the numerical solution occurring in the case of (E,B) formulation. Adequate boundary conditions are applied at the vacuum - metallic wall interface and the magnetic axis. A recently derived dielectric tensor-operator, able to describe the anisotropic plasma response in spherical tokamaks, is used for this purpose; except for its linear character, no physical or geometrical limitations are imposed on it. The equilibrium profiles (magnetic field, pressure and current) are obtained from a numerical solution of the Grad-Shafranov equation. Specifically, the wave equation is solved by the aid of a numerical code we developed for the present problem, based on the well documented 2(1/2)D finite element solver proposed by E.G. Sewell. With the definitions V i (θ,ρ) = U i (-θ,ρ) (V i U i = A j , Φ; j = ρ,φ,θ), our code solves simultaneously 16 second order partial differential equations (eight equations for each of real and imaginary set of functions V i , U i ). A systematic analysis of the solutions obtained for various values and combinations of wavenumbers and frequencies in the Alfven range is presented
D'Alessandro, Luca; Bahr, Bichoy; Daniel, Luca; Weinstein, Dana; Ardito, Raffaele
2017-09-01
The use of Phononic Crystals (PnCs) as smart materials in structures and microstructures is growing due to their tunable dynamical properties and to the wide range of possible applications. PnCs are periodic structures that exhibit elastic wave scattering for a certain band of frequencies (called bandgap), depending on the geometric and material properties of the fundamental unit cell of the crystal. PnCs slabs can be represented by plane-extruded structures composed of a single material with periodic perforations. Such a configuration is very interesting, especially in Micro Electro-Mechanical Systems industry, due to the easy fabrication procedure. A lot of topologies can be found in the literature for PnCs with square-symmetric unit cell that exhibit complete 2D bandgaps; however, due to the application demand, it is desirable to find the best topologies in order to guarantee full bandgaps referred to in-plane wave propagation in the complete 3D structure. In this work, by means of a novel and fast implementation of the Bidirectional Evolutionary Structural Optimization technique, shape optimization is conducted on the hole shape obtaining several topologies, also with non-square-symmetric unit cell, endowed with complete 3D full bandgaps for in-plane waves. Model order reduction technique is adopted to reduce the computational time in the wave dispersion analysis. The 3D features of the PnC unit cell endowed with the widest full bandgap are then completely analyzed, paying attention to engineering design issues.
ORNL diagnostic and modeling development for LAPD ICRF experiments
Isler, R. C.; Caughman, J. B. O.; Lau, C.; Martin, E. H.; Perkins, R. J.; Compernolle, B. Van; Vincena, S.; Tripathi, S. K. P.; Gekelman, W.
2017-10-01
PPPL, UCLA, and ORNL scientists have recently collaborated on a three week ICRF campaign at the upgraded LAPD device to study near field-plasma interactions associated with a single strap antenna driven at 2.38 MHz with 100 kW of RF power. This poster highlights ORNL involvement through implementation of the following diagnostics: an optical emission probe to measure neutral density, a retarding field energy analyzer to measure fast ions, phase locked imaging to measure line integrated RF-driven optical emission fluctuations, and an RF compensated triple Langmuir probe to measure density and temperature. To interpret the results of the experimental campaign a 3D cold plasma finite element model with realistic antenna and vacuum vessel geometry was developed in COMSOL. A summary of these results will be discussed. Highlights include a proof of principle localized and spatially resolved measurement of the neutral density, a strong increase in RF-driven optical emission fluctuations directly in front of the RF antenna strap, a shift in fast ion energies near the plasma edge, and qualitative agreement between the COMSOL cold plasma model with the various diagnostics. Funded by the DOE OFES (DE-AC05-00OR22725, DE-AC02-09CH11466, and DE-FC02-07ER54918) and the Univ. of California (12-LR-237124).
Ion and electron heating in ICRF heating experiments on LHD
Energy Technology Data Exchange (ETDEWEB)
Saito, K. [Nagoya Univ. (Japan). Faculty of Engineering; Kumazawa, R.; Mutoh, T. [National Inst. for Fusion Science, Toki, Gifu (Japan)] [and others
2001-02-01
This paper reports on the Ion Cyclotron Range of Frequency (ICRF) heating conducted in 1999 in the 3rd experimental campaign on the Large Helical Device (LHD) with an emphasis on the optimization of the heating regime. Specifically, an exhaustive study of seven different heating regimes was carried out by changing the RF frequency relative to the magnetic field intensity, and the dependence of the heating efficiency on H-minority concentration was investigated. It was found in the experiment that both ion and electron heating are attainable with the same experimental setup by properly choosing the frequency relative to the magnetic field intensity. In the cases of both electron heating and ion heating, the power absorption efficiency depends on the minority ion concentration. An optimum minority concentration exists in the ion heating case while, in the electron heating case, the efficiency increases with concentration monotonically. A simple model calculation is introduced to provide a heuristic understanding of these experimental results. Among the heating regimes examined in this experiment, one of the ion heating regimes was finally chosen as the optimized heating regime and various high performance discharges were realized with it. (author)
Fang, Yuan; Yu, Jianjun; Chi, Nan; Xiao, Jiangnan
2014-01-27
We experimentally demonstrated full-duplex bidirectional transmission of 10-Gb/s millimeter-wave (mm-wave) quadrature phase shift keying (QPSK) signal in E-band (71-76 GHz and 81-86 GHz) optical wireless link. Single-mode fibers (SMF) are connected at both sides of the antenna for uplink and downlink which realize 40-km SMF and 2-m wireless link for bidirectional transmission simultaneously. We utilized multi-level modulation format and coherent detection in such E-band optical wireless link for the first time. Mm-wave QPSK signal is generated by photonic technique to increase spectrum efficiency and received signal is coherently detected to improve receiver sensitivity. After the coherent detection, digital signal processing is utilized to compensate impairments of devices and transmission link.
Design and RF Test of Broadband Coaxial Hybrid Splitter for ITER ICRF System
Energy Technology Data Exchange (ETDEWEB)
Kim, H. J.; Wang, S. J.; Park, B. H.; Yang, H. L.; Kwak, J. G. [National Fusion Research Institute, Daejeon (Korea, Republic of); Choi, J. J. [Kwangwoon Univ., Seoul (Korea, Republic of)
2013-10-15
The ICRF system of the ITER is required to couple 20 MW to the plasma in the 40∼55 MHz frequency band for RF heating and current drive operation. The corresponding matching system of ICRF antenna must be load-resilient for a wide range of antenna load variations due to mode transitions or edge localized modes. Indeed the use of hybrid splitters ensures that no reflections occur at the generator when the reflections on the adjacent lines are equal both in magnitude and in phase, in which case all reflected power will not be seen by the generators and will be returned to the dummy loads. Most 3 dB coaxial hybrid circuits installed and implemented on the ICRF system is single section coupler providing best performance at the design frequency with narrow bandwidth. The bandwidth of such a single-section 3 dB hybrid coupler is limited to less than 20% due to the quarter wavelength transmission line requirement. The amplitude balance becomes rapidly degraded away from the center frequency. We designed, fabricated and tested a high power, ultra-wideband two-section 3 dB coaxial hybrid coupler over all frequencies from 40 MHz to 55 MHz for ITER ICRF system by configuring asymmetric impedance matching. We have designed, fabricated, and tested a 3-dB wideband hybrid coupler for stable and load resilient operation of the ITER ICRF system. The wideband two section 3-dB coaxial hybrid coupler was well designed by configuring asymmetric impedance matching using HFSS. In the rf measurements, we found that wideband hybrid splitter has an amplitude imbalance of 0.1 dB over all frequencies from 40 MHz to 55 MHz. We expect that wideband hybrid splitter will be applicable to ITER ICRF matching system for load resilient operation at fusion plasmas.
Spectral Effects on Fast Wave Core Heating and Current Drive
International Nuclear Information System (INIS)
Phillips, C.K.; Bell, R.E.; Berry, L.A.; Bonoli, P.T.; Harvey, R.W.; Hosea, J.C.; Jaeger, E.F.; LeBlanc, B.P.; Ryan, P.M.; Taylor, G.; Valeo, E.J.; Wilson, J.R.; Wright, J.C.; Yuh, H. and the NSTX Team
2009-01-01
Recent results obtained with high harmonic fast wave (HHFW) heating and current drive (CD) on NSTX strongly support the hypothesis that the onset of perpendicular fast wave propagation right at or very near the launcher is a primary cause for a reduction in core heating efficiency at long wavelengths that is also observed in ICRF heating experiments in numerous tokamaks. A dramatic increase in core heating efficiency was first achieved in NSTX L-mode helium majority plasmas when the onset for perpendicular wave propagation was moved away from the antenna and nearby vessel structures. Efficient core heating in deuterium majority L mode and H mode discharges, in which the edge density is typically higher than in comparable helium majority plasmas, was then accomplished by reducing the edge density in front of the launcher with lithium conditioning and avoiding operational points prone to instabilities. These results indicate that careful tailoring of the edge density profiles in ITER should be considered to limit rf power losses to the antenna and plasma facing materials. Finally, in plasmas with reduced rf power losses in the edge regions, the first direct measurements of high harmonic fast wave current drive were obtained with the motional Stark effect (MSE) diagnostic. The location and radial dependence of HHFW CD measured by MSE are in reasonable agreement with predictions from both full wave and ray tracing simulations
Energy Technology Data Exchange (ETDEWEB)
Meneghini, Orso [General Atomics, San Diego, California 92121 (United States); Volpe, Francesco A., E-mail: fvolpe@columbia.edu [Department of Applied Physics and Applied Mathematics, Columbia University, New York, New York 10027 (United States)
2016-11-15
An innovative millimeter wave diagnostic is proposed to measure the local magnetic field and edge current as a function of the minor radius in the tokamak pedestal region. The idea is to identify the direction of minimum reflectivity at the O-mode cutoff layer. Correspondingly, the transmissivity due to O-X mode conversion is maximum. That direction, and the angular map of reflectivity around it, contains information on the magnetic field vector B at the cutoff layer. Probing the plasma with different wave frequencies provides the radial profile of B. Full-wave finite-element simulations are presented here in 2D slab geometry. Modeling confirms the existence of a minimum in reflectivity that depends on the magnetic field at the cutoff, as expected from mode conversion physics, giving confidence in the feasibility of the diagnostic. The proposed reflectometric approach is expected to yield superior signal-to-noise ratio and to access wider ranges of density and magnetic field, compared with related radiometric techniques that require the plasma to emit electron Bernstein waves. Due to computational limitations, frequencies of 10-20 GHz were considered in this initial study. Frequencies above the edge electron-cyclotron frequency (f > 28 GHz here) would be preferable for the experiment, because the upper hybrid resonance and right cutoff would lie in the plasma, and would help separate the O-mode of interest from spurious X-waves.
Energy Technology Data Exchange (ETDEWEB)
Titov, O.; Stanford, Laura M. [Geoscience Australia, P.O. Box 378, Canberra, ACT 2601 (Australia); Pursimo, T. [Nordic Optical Telescope, Nordic Optical Telescope Apartado 474E-38700 Santa Cruz de La Palma, Santa Cruz de Tenerife (Spain); Johnston, Helen M.; Hunstead, Richard W. [Sydney Institute for Astronomy, School of Physics, University of Sydney, NSW 2006 (Australia); Jauncey, David L. [CSIRO Astronomy and Space Science, ATNF and Mount Stromlo Observatory, Cotter Road, Weston, ACT 2611 (Australia); Zenere, Katrina A., E-mail: oleg.titov@ga.gov.au [School of Physics, University of Sydney, NSW 2006 (Australia)
2017-04-01
In extending our spectroscopic program, which targets sources drawn from the International Celestial Reference Frame (ICRF) Catalog, we have obtained spectra for ∼160 compact, flat-spectrum radio sources and determined redshifts for 112 quasars and radio galaxies. A further 14 sources with featureless spectra have been classified as BL Lac objects. Spectra were obtained at three telescopes: the 3.58 m European Southern Observatory New Technology Telescope, and the two 8.2 m Gemini telescopes in Hawaii and Chile. While most of the sources are powerful quasars, a significant fraction of radio galaxies is also included from the list of non-defining ICRF radio sources.
Combined therapy of the Walker-256 carcinosarcoma with X-rays and ICRF-159
International Nuclear Information System (INIS)
Schaphaus, A.
1974-01-01
The radiosensitivity of the Walker-256 carcinosarcoma of the rat under the influence of the tumour-inhibiting bisdioxopiperazine ICRF-159 was studied in collectives of 11-16 animals with tumours. In the combined radio- and chemotherapy, the animals received a daily i.p. injection of 30 mg/kg K.G. of the bisdioxopiperazine ICRF-159 in 1.0 ml NaCl solution containing carboxyl methyl cellulose. The tumour inhibition was determined by multidimensional measurements of the increase in tumour size with the aid of a slide gange. The combined therapy had a better inhibiting effect on tumour growth than radiotherapy alone. (orig./AK) [de
Roucou, Anthony; Fontanari, Daniele; Dhont, Guillaume; Jabri, Atef; Bray, Cédric; Hindle, Francis; Mouret, Gaël; Bocquet, Robin; Cuisset, Arnaud
2018-03-30
Room temperature millimeter-wave rotational spectroscopy supported by high level of theory calculations have been employed to fully characterise the conformational landscape of 3-Methoxyphenol, a semi-volatile polar oxygenated aromatic compound precursor of secondary organic aerosols in the atmosphere arising from biomass combustion. While previous rotationally-resolved spectroscopic studies in the microwave and in the UV domains failed to observe the complete conformational landscape, the 70 - 330 GHz rotational spectrum measured in this study reveals the ground state rotational signatures of the four stable conformations theoretically predicted. Moreover, rotational transitions in the lowest energy vibrationally excited states were assigned for two conformers. While the inertial defect of methoxyphenol does not signicantly change between conformers and isomers, the excitation of the methoxy out-of-plane bending is the main contribution to the non-planarity of the molecule. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.
Confinement characteristics of high-energy ions produced by ICRF heating in the large helical device
International Nuclear Information System (INIS)
Kumazawa, R; Saito, K; Torii, Y; Mutoh, T; Seki, T; Watari, T; Osakabe, M; Murakami, S; Sasao, M; Watanabe, T; Yamamoto, T; Notake, T; Takeuchi, N; Saida, T; Shimpo, F; Nomura, G; Yokota, M; Kato, A; Zao, Y; Okada, H; Isobe, M; Ozaki, T; Narihara, K; Nagayama, Y; Inagaki, S; Morita, S; Krasilnikov, A V; Idei, H; Kubo, S; Ohkubo, K; Sato, M; Shimozuma, T; Yoshimura, Y; Ikeda, K; Nagaoka, K; Oka, Y; Takeiri, Y; Tsumori, K; Ashikawa, N; Emoto, M; Funaba, H; Goto, M; Ida, K; Kobuchi, T; Liang, Y; Masuzaki, S; Minami, T; Miyazawa, J; Morisaki, T; Muto, S; Nakamura, Y; Nakanishi, H; Nishimura, K; Noda, N; Ohdachi, S; Peterson, B J; Sagara, A; Sakakibara, S; Sakamoto, R; Sato, K; Shoji, M; Suzuki, H; Tanaka, K; Toi, K; Tokuzawa, T; Watanabe, K Y; Yamada, I; Yamamoto, S; Yoshinuma, M; Yokoyama, M; Watanabe, K-Y; Kaneko, O; Kawahata, K; Komori, A; Ohyabu, N; Yamada, H; Yamazaki, K; Sudo, S; Matsuoka, K; Hamada, Y; Motojima, O; Fujiwara, M
2003-01-01
The behaviour of high-energy ions accelerated by an ion cyclotron range of frequency (ICRF) electric field in the large helical device (LHD) is discussed. A better confinement performance of high-energy ions in the inward-shifted magnetic axis configuration was experimentally verified by measuring their energy spectrum and comparing it with the effective temperature determined by an electron slowing down process. In the standard magnetic axis configuration a saturation of the measured tail temperature was observed as the effective temperature was increased. The ratio between these two quantities is a measure of the quality of transfer efficiency from high-energy ions to a bulk plasma; when this efficiency was compared with Monte Carlo simulations the results agreed fairly well. The ratio of the stored energy of the high-energy ions to that of the bulk plasma was measured using an ICRF heating power modulation method; it was deduced from phase differences between total and bulk plasma stored energies and the modulated ICRF heating power. The measured high energy fraction agreed with that calculated using the injected ICRF heating power, the transfer efficiency determined in the experiment and the confinement scaling of the LHD plasma
Effects of ICRF-187 and L-Carnitine on bleomycin-induced lung toxicity in rats
International Nuclear Information System (INIS)
Shouman, Samia A.; Abdel-Hamid, M.A.; Hassan, Zeinab A.; Mansour, Heba H.
2002-01-01
The possible modulatory effects of ICRF-187 and L-carnitine against bleomycin-induced pulmonary toxicity in male rats were investigated. Repeated administration of bleomycin (10 mg/kg, twice weekly for 6 consecutive weeks) produced significant lung toxicity. The toxicity was manifested by significant increase in normal contents of lipid peroxide (LPO, 91.7%) reduced glutathione (GSH, 73.2%) and oxidized glutathione (GSSG, 135.4%) as well as the activity of superoxide dismutase (SOD, 222.7%). Thirty minutes prior to bleomycin treatment, other groups of rats received either ICRF-187 (95 mg/kg) or L-carnitine (500 mg/kg) adopting the same schedule of treatment as in bleomycin-treated group. L-carnitine decreased bleomycin-induced elevations in SOD activity, GSH and GSSG contents, however, it failed to suppress the increase in LPO level. On the other hand, treatment with ICRF-187 returned back all the elevated biochemical parameters induced by bleomycin to nearly normal levels. In conclusion, the results of this study showed a potential capability of ICRF-187 to mitigate the bleomycin-induced lung injury. Moreover, despite the inability of L-carnitine to change the elevated LPO content, it was able however, to decrease the elevated endogenous antioxidant parameters. (author)
A thermal transport coefficient for ohmic and ICRF plasmas in alcator C-mode
International Nuclear Information System (INIS)
Daughton, W.; Coppi, B.; Greenwald, M.
1996-01-01
The energy confinement in plasmas produced by Alcator C-Mod machine is markedly different from that observed by previous high field compact machines such as Alcator A and C, FT, and more recently FTU. For ohmic plasmas at low and moderate densities, the confinement times routinely exceed those expected from the so-called open-quotes neo-Alcatorclose quotes scaling by a factor as high as three. For both ohmic and ICRF heated plasmas, the energy confinement time increases with the current and is approximately independent of the density. The similarity in the confinement between the ohmic and ICRF regimes opens the possibility that the thermal transport in Alcator C-Mod may be described by one transport coefficient for both regimes. We introduce a modified form of a transport coefficient previously used to describe ohmic plasmas in Alcator C-Mod. The coefficient is inspired by the properties of the so-called open-quotes ubiquitousclose quotes mode that can be excited in the presence of a significant fraction of trapped electrons and also includes the constraint of profile consistency. A detailed series of transport simulations are used to show that the proposed coefficient can reproduce the observed temperature profiles, loop voltage and energy confinement time for both ohmic and ICRF discharges. A total of nearly two dozen ohmic and ICRF Alcator C-Mod discharges have been fit over the range of parameter space available using this transport coefficient
Efficiencies of the ICRF minority heating in the CHS and LHD plasmas
International Nuclear Information System (INIS)
Murakami, S.; Okamoto, M.; Nakajima, N.; Mutoh, T.
1994-01-01
ICRF minority heatings are investigated in the plasmas of the Compact Helical System (CHS) and the Large Helical Device (LHD) by means of the orbit following Monte Carlo simulation. It is found that the heating efficiency decreases with increase of the absorption power by minority ions and depends strongly on the magnetic field strength and the field configuration. (author)
Expanding the operating space of ICRF on JET with a view to ITER
DEFF Research Database (Denmark)
Lamalle, P.U.; Mantsinen, M.J.; Noterdaeme, J.M.
2006-01-01
when the 3 He concentration increased above similar to 2%. In the latter regime the best heating performance (a maximum electron temperature of 8 keV with 5 MW of ICRF power) was achieved with dipole array phasing, i.e. a symmetric antenna power spectrum. Minority heating of deuterium in hydrogen...
International Nuclear Information System (INIS)
Anderson, A.; Eriksson, L.G.; Lisak, M.
1986-01-01
The present report summarizes the work performed within the contract JT4/9008, the aim of which is to derive analytical models for ion velocity distributions resulting from ICRF heating on JET. The work has been performed over a two-year-period ending in August 1986 and has involved a total effort of 2.4 man years. (author)
DEFF Research Database (Denmark)
Ibsen, Lars Bo
2008-01-01
Estimates for the amount of potential wave energy in the world range from 1-10 TW. The World Energy Council estimates that a potential 2TW of energy is available from the world’s oceans, which is the equivalent of twice the world’s electricity production. Whilst the recoverable resource is many...... times smaller it remains very high. For example, whilst there is enough potential wave power off the UK to supply the electricity demands several times over, the economically recoverable resource for the UK is estimated at 25% of current demand; a lot less, but a very substantial amount nonetheless....
Wu, Hao; Masaki, Kazuaki; Irikura, Kojiro; Sánchez-Sesma, Francisco José
2017-12-01
Under the diffuse field approximation, the full-wave (FW) microtremor H/ V spectral ratio ( H/ V) is modeled as the square root of the ratio of the sum of imaginary parts of the Green's function of the horizontal components to that of the vertical one. For a given layered medium, the FW H/ V can be well approximated with only surface waves (SW) H/ V of the "cap-layered" medium which consists of the given layered medium and a new larger velocity half-space (cap layer) at large depth. Because the contribution of surface waves can be simply obtained by the residue theorem, the computation of SW H/ V of cap-layered medium is faster than that of FW H/ V evaluated by discrete wavenumber method and contour integration method. The simplified computation of SW H/ V was then applied to identify the underground velocity structures at six KiK-net strong-motion stations. The inverted underground velocity structures were used to evaluate FW H/ Vs which were consistent with the SW H/ Vs of corresponding cap-layered media. The previous study on surface waves H/ Vs proposed with the distributed surface sources assumption and a fixed Rayleigh-to-Love waves amplitude ratio for horizontal motions showed a good agreement with the SW H/ Vs of our study. The consistency between observed and theoretical spectral ratios, such as the earthquake motions of H/ V spectral ratio and spectral ratio of horizontal motions between surface and bottom of borehole, indicated that the underground velocity structures identified from SW H/ V of cap-layered medium were well resolved by the new method.[Figure not available: see fulltext.
Directory of Open Access Journals (Sweden)
Predrag Pejovic
2013-12-01
Full Text Available Application of a single phase rectifier as an example in teaching circuit modeling, normalization, operating modes of nonlinear circuits, and circuit analysis methods is proposed.The rectifier supplied from a voltage source by an inductive impedance is analyzed in the discontinuous as well as in the continuous conduction mode. Completely analytical solution for the continuous conduction mode is derived. Appropriate numerical methods are proposed to obtain the circuit waveforms in both of the operating modes, and to compute the performance parameters. Source code of the program that performs such computation is provided.
Fast wave current drive technology development at ORNL
International Nuclear Information System (INIS)
Baity, F.W.; Batchelor, D.B.; Goulding, R.H.; Hoffman, D.J.; Jaeger, E.F.; Ryan, P.M.; deGrassie, J.S.; Petty, C.C.; Pinsker, R.I.; Prater, R.
1993-01-01
The technology required for fast wave current drive (FWCD) systems is discussed. Experiments are underway on DIII-D, JET, and elsewhere. Antennas for FWCD draw heavily upon the experience gained in the design of ICRF heating systems with the additional requirement of launching a directional wave spectrum. Through collaborations with DIII-D, JET, and Tore Supra rapid progress is being made in the demonstration of the physics and technology of FWCD needed for TPX and ITER
Fast wave current drive technology development at ORNL
International Nuclear Information System (INIS)
Baity, F.W.; Batchelor, D.B.; Goulding, R.H.
1994-01-01
The technology required for fast wave current drive (FWCD) systems is discussed. Experiments are underway on DIII-D, JET, and elsewhere. Antennas for FWCD draw heavily upon the experience gained in the design of ICRF heating systems with the additional requirement of launching a directional wave spectrum. Through collaborations with DIII-D, JET, and Tore Supra rapid progress is being made in the demonstration of the physics and technology of FWCD needed for TPX and ITER. (author)
Possible effects of RF field near ICRF antenna on density control during long pulse discharge in LHD
International Nuclear Information System (INIS)
Saito, K.; Kumazawa, R.; Mutoh, T.; Seki, T.; Watari, T.; Nakamura, Y.; Sakamoto, M.; Noda, N.; Watanabe, T.; Shoji, M.; Masuzaki, S.; Morita, S.; Goto, M.; Torii, Y.; Takeuchi, N.; Shimpo, F.; Nomura, G.; Yokota, M.; Kato, A.; Zhao, Y.
2005-01-01
In the large helical device (LHD), the plasma duration time was extended up to 150 s by ion cyclotron range of frequencies (ICRF) heating. Time-integrated total input power reached 71 MJ. However, this discharge terminated due to radiation collapse accompanied by an increase of electron density. The temperature of the divertor plates and the intensity of H α were locally increased in the same toroidal section, near the ICRF antenna. One of the possible causes of the increase of radiation power is an outgassing from the divertor plates that were heated by particles accelerated in the cyclotron resonance layer near the antenna. Another possible cause is the outgassing from the ICRF antenna itself due to a temperature increase of the ICRF antenna owing to high-energy particles, or the formation of an RF (radio frequency) sheath
Zeff measurements and low-Z impurity transport for NBI and ICRF heated plasma in JIPP T-IIU tokamak
International Nuclear Information System (INIS)
Ida, K.; Amano, T.; Kawahata, K.; Kaneko, O.
1988-12-01
A visible bremsstrahlung detector array system for Z eff measurements and a charge exchange recombination spectroscopy (CXRS) system for fully ionized impurity profile measurements were installed on JIPP TII-U to study impurity transport for NBI and ICRF heated plasma. More impurities are sputtered by ICRF heating than by NBI and/or ohmic heatings. The carbon contribution to Z eff is 80-90 % for NBI heated plasmas, and 60 % for NBI + ICRF heated plasmas. With a carbon coating of vacuum vessel, the Z eff value decreases 2.4 to 1.7 and the carbon contribution to Z eff increases up to 80-90 %. We obtain the diffusion coefficient D a = 1.0 m 2 /s and the convective velocity V a (a) = 13 m/s at the plasma edge for carbon impurity from the radial profile and time evolution of fully ionized carbon after the ICRF pulse is turned on. (author)
International Nuclear Information System (INIS)
Monakhov, I.; Becoulet, A.; Fraboulet, D.; NGuyen, F.
1998-09-01
A consistent picture of the mode conversion (MC) process at the ion-ion hybrid resonance in a bounded plasma of a tokamak is discussed, which clarifies the role of the global fast wave interference and cavity effects in the determination of the MC efficiency. This picture is supported by simulations with one-dimensional full wave kinetic code 'VICE'. The concept of the 'global resonator', formed by the R = n 2 || boundary cutoffs [B. Saoutic et al., Phys. Rev. Lett. 76, 1647 (1996)], is justified, as well as the importance of a proper tunneling factor choice η cr = 0.22 [A. K. Ram et al., Phys. Plasmas 3, 1976 (1996)]. The MC scheme behavior appears to be very sensitive to the MC layer position relative to the global wave field pattern, i.e. to the local value of 'poloidal' electric field at the resonance. Optimal MC regimes are found to be attainable without requirement of a particular parallel wavenumber choice. (author)
International Nuclear Information System (INIS)
Michalicek, Gregor
2015-01-01
Density functional theory (DFT) is the most widely-used first-principles theory for analyzing, describing and predicting the properties of solids based on the fundamental laws of quantum mechanics. The success of the theory is a consequence of powerful approximations to the unknown exchange and correlation energy of the interacting electrons and of sophisticated electronic structure methods that enable the computation of the density functional equations on a computer. A widely used electronic structure method is the full-potential linearized augmented plane-wave (FLAPW) method, that is considered to be one of the most precise methods of its kind and often referred to as a standard. Challenged by the demand of treating chemically and structurally increasingly more complex solids, in this thesis this method is revisited and extended along two different directions: (i) precision and (ii) efficiency. In the full-potential linearized augmented plane-wave method the space of a solid is partitioned into nearly touching spheres, centered at each atom, and the remaining interstitial region between the spheres. The Kohn-Sham orbitals, which are used to construct the electron density, the essential quantity in DFT, are expanded into a linearized augmented plane-wave basis, which consists of plane waves in the interstitial region and angular momentum dependent radial functions in the spheres. In this thesis it is shown that for certain types of materials, e.g., materials with very broad electron bands or large band gaps, or materials that allow the usage of large space-filling spheres, the variational freedom of the basis in the spheres has to be extended in order to represent the Kohn-Sham orbitals with high precision over a large energy spread. Two kinds of additional radial functions confined to the spheres, so-called local orbitals, are evaluated and found to successfully eliminate this error. A new efficient basis set is developed, named linearized augmented lattice
Damping mechanisms and heating scenarii in the ICRF
International Nuclear Information System (INIS)
Jacquinot, J.; Lapierre, Y.
1980-09-01
A wave damping and heating model is presented. It permits to treat a wide range of plasma parameters and complex ion species composition. Applied to JET parameters, two selected wave scenarii are found to allow a great flexibility, in particular with respect to complex gas composition. A major results is the possibility of single pass absorption
Energy Technology Data Exchange (ETDEWEB)
Silva, F. da [Associao EURATOM/IST, IPFN-LA, Instituto Superor Tecnico, Lisbon (Portugal); Heuraux, S. [Institut Jean Lamour, CNRS-Nancy-Universite, BP70239, Vandoeuvre-les-Nancy (France); Gusakov, E.; Popov, A. [Ioffe Institute, Polytekhnicheskaya, St Petersburg (Russian Federation)
2011-07-01
Forward-scattering under high level of turbulence or long propagation paths can induce significant effects, as predicted by theory, and impose a signature on the Doppler reflectometry response. Simulations using a FDTD (finite-difference time-domain) full-wave code have confirmed the main dependencies and general behavior described by theory but display a returned RMS power, at moderate amplitudes, half of the one predicted by theory due to the impossibility to reach the numerical requirements needed to describe the small wavenumber spectrum with the wanted accuracy.One justifying factor may be due to the splitting and enlargement of the probing beam. At high turbulence levels, the scattered power returning to the antenna is higher than the predicted by the theory probably due to the scattered zone being closer than the oblique cutoff. This loss of coherence of the wavefront induces a beam spreading, which is also responsible for a diminution of the wavenumber resolution. With a FDTD full-wave code we study the behavior of the probing beam under several amplitude levels of low wavenumber plasma turbulence, using long temporal simulations series to ensure statistical accuracy. (authors)
ICRF experiments and potential formation on the GAMMA 10 tandem mirror
International Nuclear Information System (INIS)
Ichimura, M.; Cho, T.; Higaki, H.
2005-01-01
Target plasmas, on which the formation of the electrostatic potentials and the improvement of the confinement are studied, are produced with ICRF in the GAMMA 10 tandem mirror. The ion temperature of more than 10 keV has been achieved in relatively low density plasmas. When the strong ICRF heating is applied, it is observed that the high frequency and the low frequency fluctuations are excited and suppress the increase in the plasma parameters. Recently, a new high power gyrotron system has been constructed and the plug ECRH power extends up to 370 kW. The improvement of the confinement due to the formation of the potential in the axial direction and the strong radial electric field shear has been observed. (author)
Coupling of an ICRF compact loop antenna to H-mode plasmas in DIII-D
International Nuclear Information System (INIS)
Mayberry, M.J.; Baity, F.W.; Hoffman, D.J.; Luxon, J.L.; Owens, T.L.; Prater, R.
1987-01-01
Low power coupling tests have been carried out with a prototype ICRF compact loop antenna on the DIII-D tokamak. During neutral-beam-heated L-mode discharges the antenna loading is typically R≅1-2Ω for an rf frequency of 32 MHz (B/sub T/ = 21 kG, ω = 2Ω/sub D/(0)). When a transition into the H-mode regime of improved confinement occurs, the loading drops to R≅0.5-1.0Ω. During ELMs, transient increases in loading up to several Ohms are observed. The apparent sensitivity of ICRF antenna coupling to changes in the edge plasma profiles associated with the H-mode regime could have important implications for the design of future high power systems
The healthiness of JT-60 ICRF antenna and development of its temperature measurement device
International Nuclear Information System (INIS)
Hiranai, Shinichi; Yokokura, Kenji; Moriyama, Shinichi; Sato, Tomio; Ishii, Kazuhiro; Fujii, Tsuneyuki
1998-03-01
Ion Cyclotron Range of Frequency (ICRF) heating system in JT-60 employs two antennas to couple RF power in the range of 100 MHz to the plasma. The antennas are installed in the vacuum vessel of JT-60, facing to the high temperature plasma. Due to the severe heat load from the plasma, parts of the antenna surface are suffering from melt. It is important to investigate the mechanism of the heat load and the melting. 'Temperature measurement for ICRF antenna surface' employing an infrared thermographic camera has been developed, in order to investigate the heat load to the antenna and to maintain the antenna available. We have succeeded in minimizing the melting damage of the antenna surface using the temperature measurement device. (author)
3-D analysis on arbitrarily-shaped ICRF antennas and Faraday shields
International Nuclear Information System (INIS)
Chen, G.L.; Whealton, J.H.; Baity, F.W.; Hoffman, D.J.; Owens, T.L.
1986-01-01
Cavity antennas with Faraday shields are proposed to couple ion cyclotron radio frequency power for heating fusion plasmas. This application requires small, high-power, low-frequency antennas. The results are presented of a theoretical study of the ICRF antennas being developed for this purpose at the Radio Frequency Test Facility (RFTF). The objectives of this work are to optimize experimental designs and to confirm test results
ICRF specific plasma wall interactions in JET with the ITER-like wall
Energy Technology Data Exchange (ETDEWEB)
Bobkov, Vl., E-mail: bobkov@ipp.mpg.de [Max-Planck-Institut für Plasmaphysik, EURATOM Association, Garching (Germany); Arnoux, G. [Culham Science Centre, Association EURATOM-CCFE, Abingdon, Oxon (United Kingdom); Brezinsek, S.; Coenen, J.W. [Institute of Energy and Climate Research, Association EURATOM-FZJ (Germany); Colas, L. [CEA, IRFM, F-13108 St. Paul-lez-Durance (France); Clever, M. [Institute of Energy and Climate Research, Association EURATOM-FZJ (Germany); Czarnecka, A. [Association EURATOM-IPPLM, Hery 23, 01-497 Warsaw (Poland); Braun, F.; Dux, R. [Max-Planck-Institut für Plasmaphysik, EURATOM Association, Garching (Germany); Huber, A. [Institute of Energy and Climate Research, Association EURATOM-FZJ (Germany); Jacquet, P. [Culham Science Centre, Association EURATOM-CCFE, Abingdon, Oxon (United Kingdom); Klepper, C. [CEA, IRFM, F-13108 St. Paul-lez-Durance (France); Lerche, E. [LPP-ERM/KMS, Association Euratom-Belgian State, TEC Partners, Brussels (Belgium); Maggi, C. [Max-Planck-Institut für Plasmaphysik, EURATOM Association, Garching (Germany); Marcotte, F. [CEA, IRFM, F-13108 St. Paul-lez-Durance (France); Maslov, M.; Matthews, G.; Mayoral, M.L. [Culham Science Centre, Association EURATOM-CCFE, Abingdon, Oxon (United Kingdom); McCormick, K. [Max-Planck-Institut für Plasmaphysik, EURATOM Association, Garching (Germany); Meigs, A. [Culham Science Centre, Association EURATOM-CCFE, Abingdon, Oxon (United Kingdom); and others
2013-07-15
A variety of plasma wall interactions (PWIs) during operation of the so-called A2 ICRF antennas is observed in JET with the ITER-like wall. Amongst effects of the PWIs, the W content increase is the most significant, especially at low plasma densities. No increase of W source from the main divertor and entrance of the outer divertor during ICRF compared to NBI phases was found by means of spectroscopic and WI (400.9 nm) imaging diagnostics. In contrary, the W flux there is higher during NBI. Charge exchange neutrals of hydrogen isotopes could be excluded as considerable contributors to the W source. The high W content in ICRF heated limiter discharges suggests the possibility of other W sources than the divertor alone. Dependencies of PWIs to individual ICRF antennas during q{sub 95}-scans, and intensification of those for the −90° phasing, indicate a link between the PWIs and the antenna near-fields. The PWIs include heat loads and Be sputtering pattern on antenna limiters. Indications of some PWIs at the outer divertor entrance are observed which do not result in higher W flux compared to the NBI phases, but are characterized by small antenna-specific (up to 25% with respect to ohmic phases) bipolar variations of WI emission. The first TOPICA calculations show a particularity of the A2 antennas compared to the ITER antenna, due to the presence of long antenna limiters in the RF image current loop and thus high near-fields across the most part of the JET outer wall.
Maximization of ICRF power by SOL density tailoring with local gas injection
Czech Academy of Sciences Publication Activity Database
Jacquet, P.; Goniche, M.; Bobkov, V.; Lerche, E.; Pinsker, R.I.; Pitts, R.A.; Zhang, W.; Colas, L.; Hosea, J.; Moriyama, S.; Wang, S.-J.; Wukitch, S.; Zhang, X.; Bilato, R.; Bufferand, H.; Guimarais, L.; Faugel, H.; Hanson, G.R.; Kocan, M.; Monakhov, I.; Noterdaeme, J.-M.; Petržílka, Václav; Shaw, A.; Stepanov, I.; Sips, A.C.C.; Van Eester, D.; Wauters, T.
2016-01-01
Roč. 56, č. 4 (2016), s. 046001 ISSN 0029-5515 EU Projects: European Commission(XE) 633053 - EUROfusion Institutional support: RVO:61389021 Keywords : ICRF power * antenna loading * gas injection * SOL density Subject RIV: BL - Plasma and Gas Discharge Physics OBOR OECD: Fluids and plasma physics (including surface physics) Impact factor: 3.307, year: 2016 http://iopscience.iop.org/article/10.1088/0029-5515/56/4/046001
High-power and steady-state operation of ICRF heating in the large helical device
Energy Technology Data Exchange (ETDEWEB)
Mutoh, T., E-mail: mutoh@nifs.ac.jp; Seki, T.; Saito, K.; Kasahara, H.; Seki, R.; Kamio, S.; Kumazawa, R.; Kubo, S.; Shimozuma, T.; Yoshimura, Y.; Igami, H.; Takahashi, H.; Ii, T.; Makino, R.; Nagaoka, K.; Nomura, G. [National Institute for Fusion Science, 322-6, Oroshi-cho, Toki, Gifu, 509-5292 (Japan); Shinya, T. [The University of Tokyo, Kashiwa 2777-8561 (Japan)
2015-12-10
Recent progress in an ion cyclotron range of frequencies (ICRF) heating system and experiment results in a Large Helical Device (LHD) are reported. Three kinds of ICRF antenna pairs were installed in the LHD, and the operation power regimes were extended up to 4.5 MW; also, the steady-state operation was extended for more than 45 min in LHD at a MW power level. We studied ICRF heating physics in heliotron configuration using a Hand Shake type (HAS) antenna, Field Aligned Impedance Transforming (FAIT) antenna, and Poloidal Array (PA) antenna, and established the optimum minority-ion heating scenario in an LHD. The FAIT antenna having a novel impedance transformer inside the vacuum chamber could reduce the VSWR and successfully injected a higher power to plasma. We tested the PA antennas completely removing the Faraday-shield pipes to avoid breakdown and to increase the plasma coupling. The heating performance was almost the same as other antennas; however, the heating efficiency was degraded when the gap between the antenna and plasma surface was large. Using these three kinds of antennas, ICRF heating could contribute to raising the plasma beta with the second- and third-harmonic cyclotron heating mode, and also to raising the ion temperature as discharge cleaning tools. In 2014, steady-state operation plasma with a line-averaged electron density of 1.2 × 10{sup 19} m{sup −3}, ion and electron temperature of 2 keV, and plasma sustainment time of 48 min was achieved with ICH and ECH heating power of 1.2 MW for majority helium with minority hydrogen. In 2015, the higher-power steady-state operation with a heating power of up to 3 MW was tested with higher density of 3 × 10{sup 19} m{sup −3}.
Reversed magnetic shear operation with ICRF minority heating on Tore Supra
International Nuclear Information System (INIS)
Hoang, G.T.; Antar, G.; Aniel, T.
1999-01-01
This paper reports a scenario recently investigated in Tore Supra for high density and high plasma current (Ip) operation, which allows to use the ion cyclotron resonance frequency (ICRF) minority heating only for the internal transport barrier (ITB) formation. The main aim is to perform a hollow current density profile by minimizing the edge resistive skin depth during the rapid Ip ramp-up, i-e efficient freezing of the resistive current diffusion
On the role of ion heating in ICRF-heated discharges in Tore Supra
International Nuclear Information System (INIS)
Eriksson, L.G.; Hoang, G.; Bergeaud, V.
2000-09-01
The effect of bulk ion heating in Tore Supra has been investigated by studying discharges with varying concentrations of minority ions during ICRF hydrogen minority heating in Deuterium/ 4 He plasmas. As expected, the level of bulk ion heating is found to increase with the minority concentration. Higher levels of ion heating are shown to be accompanied by two significant effects: an improved energy confinement and a strong influence on the plasma rotation. (author)
Power absorption and confinement studies of ICRF-heated plasma in JIPP T-IIU tokamak
International Nuclear Information System (INIS)
Ida, K.; Ogawa, Y.; Toi, K.
1988-08-01
The energy confinement characteristics of ICRF-heated tokamak plasmas are studied at high input power density ∼ 2 MWm -3 volume averaged, on the JIPP T-IIU device(R = 0.91 m/a = 0.23 m). High electron and ion temperatures (T e ∼ 2.5 keV, T i ∼ 2.0 keV, at each maximum) have been achieved by the operation at a plasma current I P of 280 kA, plasma line-averaged electron density n-bar e of 7 x 10 13 cm -3 and input power of 2 MW, with a suppression of total radiation loss (30 to 40 % of the total input power) by a carbon coating on the vacuum vessel. The fraction of ICRF power absorbed by the plasma, α, is determined experimentally from the decay of the stored plasma energy just after the ICRF pulse is terminated. The value of α increases slightly with increasing electron density and decreases from 90 to 70 % as the ICRF power is increased from 1 MWm -3 to 2 MWm -3 volume averaged. The global energy confinement time τ E , defined by W P /(P OH + αP rf ), decreases by a factor of 2 ∼ 3 from that in ohmic plasmas as the heating power increases up to 2 MW. It is found that the energy confinement time has a strong line-averaged electron density dependence as τ E ∝n-bar e 0.6 , which is obtained by the use of the measured absorbed power, while the Kaye-Goldston scaling predicts τ E ∝n-bar e 0.26 . (author)
TRANSP modeling of minority ion sawtooth mixing in ICRF + NBI heated discharges in TFTR
International Nuclear Information System (INIS)
Goldfinger, R.C.; Batchelor, D.B.; Murakami, M.; Phillips, C.K.; Budny, R.; Hammett, G.W.; McCune, D.M.; Wilson, J.R.; Zarnstorff, M.C.
1995-01-01
Time independent code analysis indicates that the sawtooth relaxation phenomenon affects RF power deposition profiles through the mixing of fast ions. Predicted central electron heating rates are substantially above experimental values unless sawtooth relaxation is included. The PPPL time dependent transport analysis code, TRANSP, currently has a model to redistribute thermal electron and ion species, energy densities, plasma current density, and fast ions from neutral beam injection at each sawtooth event using the Kadomtsev (3) prescription. Results are presented here in which the set of models is extended to include sawtooth mixing effects on the hot ion population generated from ICRF heating. The ICRF generated hot ion distribution function, line-integral(ν parallel , ν perpendicular ), which is strongly peaked at the center before each sawtooth, is replaced throughout the sawtooth mixing volume by its volume averaged value at each sawtooth. The modified line-integral(ν parallel ,ν perpendicular ) is then used to recalculate the collisional transfer of power from the minority species to the background species. Results demonstrate that neglect of sawtooth mixing of ICRF-induced fast ions leads to prediction of faster central electron reheat rates than are measured experimentally
Modeling and simulation support for ICRF heating of fusion plasmas. Annual report, 1990
Energy Technology Data Exchange (ETDEWEB)
NONE
1990-03-15
Recent experimental, theoretical and computational results have shown the need and usefulness of a combined approach to the design, analysis and evaluation of ICH antenna configurations. The work at the University of Wisconsin (UW) in particular has shown that much needed information on the vacuum operation of ICH antennas can be obtained by a modest experimental and computational effort. These model experiments at UW and SAIC simulations have shown dramatically the potential for positive impact upon the ICRF program. Results of the UW-SAIC joint ICRF antenna analysis effort have been presented at several international meetings and numerous meetings in the United States. The PPPL bay M antenna has been modeled using the ARGUS code. The results of this effort are shown in Appendix C. SAIC has recently begun a collaboration with the ICRF antenna design and analysis group at ORNL. At present there are two separate projects underway. The first is associated with the simulation of and determination of the effect of adding slots in the antenna septum and side walls. The second project concerns the modeling and simulation of the ORNL folded waveguide (FWG) concept.
Long-Pulse Operation and High-Energy Particle Confinement Study in ICRF Heating of LHD
International Nuclear Information System (INIS)
Mutoh, Takashi; Kumazawa, Ryuhei; Seki, Tetsuo
2004-01-01
Long-pulse operation and high-energy particle confinement properties were studied using ion cyclotron range of frequency (ICRF) heating for the Large Helical Device. For the minority-ion mode, ions with energies up to 500 keV were observed by concentrating the ICRF heating power near the plasma axis. The confinement of high-energy particles was studied using the power-modulation technique. This confirmed that the confinement of high-energy particles was better with the inward-shifted configuration than with the normal configuration. This behavior was the same for bulk plasma confinement. Long-pulse operation for more than 2 min was achieved during the experimental program in 2002. This was mainly due to better confinement of the helically trapped particles and accumulation of fewer impurities in the region of the plasma core, in conjunction with substantial hardware improvements. Currently, the plasma operation time is limited by an unexpected density rise due to outgassing from the chamber materials. The temperature of the local carbon plates of the divertor exceeded 400 deg, C, and a charge-coupled device camera observed the hot spots. The hot spot pattern was well explained by a calculation of the accelerated-particle orbits, and those accelerated particles came from outside the plasma near the ICRF antenna
Tunable biasing magnetic field design of ferrite tuner for ICRF heating system in EAST
Manman, XU; Yuntao, SONG; Gen, CHEN; Yanping, ZHAO; Yuzhou, MAO; Guang, LIU; Zhen, PENG
2017-11-01
Ion cyclotron range of frequency (ICRF) heating has been used in tokamaks as one of the most successful auxiliary heating tools and has been adopted in the EAST. However, the antenna load will fluctuate with the change of plasma parameters in the ICRF heating process. To ensure the steady operation of the ICRF heating system in the EAST, fast ferrite tuner (FFT) has been carried out to achieve real-time impedance matching. For the requirements of the FFT impedance matching system, the magnet system of the ferrite tuner (FT) was designed by numerical simulations and experimental analysis, where the biasing magnetic circuit and alternating magnetic circuit were the key researched parts of the ferrite magnet. The integral design goal of the FT magnetic circuit is that DC bias magnetic field is 2000 Gs and alternating magnetic field is ±400 Gs. In the FTT, E-type magnetic circuit was adopted. Ferrite material is NdFeB with a thickness of 30 mm by setting the working point of NdFeB, and the ampere turn of excitation coil is 25 through the theoretical calculation and simulation analysis. The coil inductance to generate alternating magnetic field is about 7 mH. Eddy-current effect has been analyzed, while the magnetic field distribution has been measured by a Hall probe in the medium plane of the biasing magnet. Finally, the test results show the good performance of the biasing magnet satisfying the design and operating requirements of the FFT.
Monte-Carlo study of ICRF-sustained mode operation in tandem mirrors
Energy Technology Data Exchange (ETDEWEB)
Todd, A.M.M. (Grumman Aerospace Corp., Princeton, NJ (USA))
1984-09-01
A study, using a Monte-Carlo simulation code, of ICRF-sustained mode operation in tandem mirrors by way of ICRF end-cell fuelling and heating is described. Although the basic parameter space considered corresponds to the Phaedrus experiment, the central-cell density and temperatures are extended towards the reactor regime. It is found that significant end cell ion potential barriers can be generated with ICRF, but that, owing to choking of the central-cell ion source stream by the plugging potential, saturation occurs and power requirements rapidly increase, so that the potential rise is limited to about twice the central-cell ion temperature. Although performance is improved as the ion cyclotron resonance approaches the end-cell mid-plane, no significant difference is found between inboard, outboard or double resonance location. As the central-cell density and temperatures are increased, the RF power requirement is found to increase dramatically. Optimum performance for end cell fuelling results when the central-cell electron temperature is higher than the ion temperature, but the magnitude of this ratio is limited by an increase in threshold power level with electron temperature.
International Nuclear Information System (INIS)
Botros, K.K.; Geerligs, J.; Rothwell, Brian; Carlson, Lorne; Fletcher, Leigh; Venton, Philip
2010-01-01
The control of propagating ductile (or tearing) fracture is a fundamental requirement in the fracture control design of pipelines. The Battelle two-curve method developed in the early 1970s still forms the basis of the analytical framework used throughout the industry. GASDECOM is typically used for calculating decompression speed, and idealizes the decompression process as isentropic and one-dimensional, taking no account of frictional effects. While this approximation appears not to have been a major issue for large-diameter pipes and for moderate pressures (up to 12 MPa), there have been several recent full-scale burst tests at higher pressures and smaller diameters for which the measured decompression velocity has deviated progressively from the predicted values, in general towards lower velocities. The present research was focused on determining whether pipe diameter was a major factor that could limit the applicability of frictionless models such as GASDECOM. Since potential diameter effects are primarily related to wall friction, which in turn is related to the ratio of surface roughness-to-diameter, an experimental approach was developed based on keeping the diameter constant, at a sufficiently small value to allow for an economical experimental arrangement, and varying the internal roughness. A series of tests covering a range of nominal initial pressures from 10 to 21 MPa, and involving a very lean gas and three progressively richer compositions, were conducted using two specialized high-pressure shock tubes (42 m long, I.D. = 38.1 mm). The first is honed to an extremely smooth surface finish, in order to minimize frictional effects and better simulate the behaviour of larger-diameter pipelines, while the second has a higher internal surface roughness. The results show that decompression wave speeds in the rough tube are consistently slower than those in the smooth tube under the same conditions of mixture composition and initial pressure and temperature
Pietrzak, Robert H.; Goldstein, Risë B.; Southwick, Steven M.; Grant, Bridget F.
2011-01-01
Objective This study examined associations between lifetime trauma exposures, PTSD and partial PTSD, and past-year medical conditions in a nationally representative sample of U.S. adults. Methods Face-to-face interviews were conducted with 34,653 participants in the Wave 2 National Epidemiologic Survey on Alcohol and Related Conditions. Logistic regression analyses evaluated associations of trauma exposure, PTSD and partial PTSD with respondent-reported medical diagnoses. Results After adjustment for sociodemographic characteristics and comorbid Axis I and II disorders, respondents with full PTSD were more likely than traumatized respondents without full or partial PTSD (comparison group) to report diagnoses of diabetes mellitus, noncirrhotic liver disease, angina pectoris, tachycardia, hypercholesterolemia, other heart disease, stomach ulcer, HIV seropositivity, gastritis, and arthritis (odds ratios [ORs]=1.2-2.5). Respondents with partial PTSD were more likely than the comparison group to report past-year diagnoses of stomach ulcer, angina pectoris, tachycardia, and arthritis (ORs=1.3-1.6). Men with full and partial PTSD were more likely than controls to report diagnoses of hypertension (both ORs=1.6), and both men and women with PTSD (ORs=1.8 and 1.6, respectively), and men with partial PTSD (OR=2.0) were more likely to report gastritis. Total number of lifetime traumatic event types was associated with many assessed medical conditions (ORs=1.04-1.16), reducing the magnitudes and rendering non-significant some of the associations between PTSD status and medical conditions. Conclusions Greater lifetime trauma exposure and PTSD are associated with numerous medical conditions, many of which are stress-related and chronic, in U.S. adults. Partial PTSD is associated with intermediate odds of some of these conditions. PMID:21949429
International Nuclear Information System (INIS)
Bhatnagar, V.P.; Taroni, A.; Ellis, J.J.; Jacquinot, J.; Stuart, D.F.
1989-01-01
In this paper, we compare experimental results of electron and ion-heating in discharges that feature monster sawtooth with those in pellet-produced peaked-density profile discharges which were heated with ICRF. Also we carry out a comprehensive analysis of ICRF-heated peaked-density profile discharges by a transport code to simulate the evolution of JET discharges and to provide an insight into the improved heating and confinement found in these discharges. In this analysis, the ICRF power-deposition profile in the minority-heating scenario is computed by the ray-tracing code BRAYCO that self-consistently takes the finite antenna geometry, its radiation spectrum and the hot-plasma damping into account. The power delivered to ions and electrons is calculated based on Stix model. (author) 10 refs., 5 figs
Energy Technology Data Exchange (ETDEWEB)
Baker, D.; Constable, W.; Elkon, D.; Rinehart, L.
1981-11-15
Courses of irradiation consisting of 6000 rad in ten equal fractions over 12 days delivered to KHT sarcomas in mice controlled 55% of the local tumors but 83% of the mice died from metastases. Three strategies to reduce the risk of metastatic spread were tested. The fractionation scheme was changed to deliver the same total dose using a large initial fraction followed by seven equal portions with the same overall time. ICRF-159 was used with the intention of partially synchronizing the tumor growth fraction in a radiosensitive state of the growth cycle and of promoting normalization of the tumor vasculature. Levamisole was used to stimulate the immune system. The combination of ICRF-159 with the eight-fraction radiation course proved to be effective for both increasing local control and decreasing the incidence of metastases. The addition of levamisole did not improve the results obtained with a combination of ICRF-159 and irradiation.
Energy Technology Data Exchange (ETDEWEB)
Baker, D.; Constable, W.; Elkon, D.; Rinehart, L.
1981-11-15
Courses of irradiation consisting of 6000 rad in ten equal fractions over 12 days delivered to KHT sarcomas in mice controlled 55% of the local tumors but 83% of the mice died from metastases. Three strategies to reduce the risk of metastatic spread were tested. The fractionation scheme was changed to deliver the same total dose using a large initial fraction followed by seven equal portions with the same overall time. ICRF-159 was used with the intention of partially synchronizing the tumor growth fraction in a radiosensitive state of the growth cycle and of promoting normalization of the tumor vasculature. Levamisole was used to stimulate the immune system. The combination of ICRF-159 with the eight-fraction radiation course proved to be effective for both increasing local control and decreasing the incidence of metastases. The addition of levamisole did not improve the results obtained with a combination of ICRF-159 and irradiation.
Integrated Predictive Models for ICRF-Edge Plasma Interactions
International Nuclear Information System (INIS)
Daniel A. D'Ippolito
2005-01-01
The coupling of radiofrequency waves to the edge plasma of a fusion device produces strong nonlinear interactions with the plasma and surrounding material walls which must be controlled in order to protect the antenna and to obtain efficient heating of the core plasma. The goal of the STTR project was to develop the first quantitative numerical simulation of this problem. This report describes the results of the Phase I work by Lodestar and ORNL on this project
Investigation of energy confinement during ICRF heating on EAST
Yang, Y. Q.; Zhang, X. J.; Zhao, Y. P.; Qin, C. M.; Cheng, Y.; Mao, Y. Z.; Yang, H.; Yuan, S.; Wang, L.; Ju, S. Q.; Chen, G.; Zhang, J. H.; Wang, J. H.; Chen, Z.; Wan, B. N.; Gong, X. Z.; Qian, J. P.; Zhang, T.; Li, J. G.; Song, Y. T.; Lin, Y.; Taylor, G.; Hosea, J. C.; Perkins, R. J.; Wukitch, S.; Noterdaeme, J. M.; Kumazawa, R.; Seki, T.; Saito, K.; Kasahara, H.
2017-09-01
A summary is given on recent experiments in L-mode with ion cyclotron resonance heating (ICRH) of hydrogen minority in deuterium plasmas on EAST. Experiments show a degradation of confinement with increasing power. Furthermore, the energy confinement time increases with plasma current and magnetic field, whereas it is insensitive to line averaged density. Minority heating has been found to be efficient, and parameters were optimized to maximize its efficiency. ICRH in lower hybrid waves heated plasma was also investigated.
Applications of the 3-dim ICRH global wave code FISIC and comparison with other models
International Nuclear Information System (INIS)
Kruecken, T.; Brambilla, M.
1989-01-01
Numerical simulations of two ICRF heating experiments in ASDEX are presented, using the FISIC code to solve the integrodifferential wave equations in the finite Larmor radius (FLR) approximation model and of ray tracing. The different models show on the whole good agreement; we can however identify a few interesting toroidal effects, in particular on the efficiency of mode conversion and on the propagation of ion Bernstein waves. (author)
15-MeV proton emission from ICRF-heated plasmas
Energy Technology Data Exchange (ETDEWEB)
Jarvis, O N; Conroy, S W; Hone, M; Sadler, G J; Van Belle, P [Commission of the European Communities, Luxembourg (Luxembourg)
1994-07-01
{sup 3} He-d fusion reaction protons emitted from ICRF-heated discharges were recorded with a silicon diode detector installed in the JET tokamak. The detection rates demonstrated that sawtooth crashes eject fast particles from the inner region of the plasma. The energy spectra of the fusion product protons using H minority provided evidence for the second harmonic acceleration of deuterons at sub-MW levels of RF power and those with {sup 3} He minority did not possess the expected twin-lobed shape predicted by kinematics calculations. (authors). 5 refs., 6 figs.
Observations of neutral beam and ICRF tail ion losses due to Alfven modes in TFTR
International Nuclear Information System (INIS)
Darrow, D.S.; Zweben, S.J.; Chang, Z.
1996-04-01
Fast ion losses resulting from MHD modes at the Alfven frequency, such as the TAE, have been observed in TFTR. The modes have been driven both by neutral beam ions, at low B T , and by H-minority ICRF tail ions at higher B T . The measurements indicate that the loss rate varies linearly with the mode amplitude, and that the fast ion losses during the mode activity can be significant, e.g. up to 10% of the input power is lost in the worst case
Electromagnetic analysis of the Faraday shield of the EAST ICRF antenna
International Nuclear Information System (INIS)
Yang Qingxi; Song Yuntao; Wu Songtao; Zhao Yanping
2011-01-01
Faraday shield is one of the important components of ICRF antenna for EAST. In view of the structural safety of the Faraday shield, the electromagnetic and structural analyses for the Faraday shield have been carried out by applying the finite element method and the formulas under the cases of plasma disruption and vertical displacement event (VDE). Results of the electromagnetic forces, the stresses distribution as well as the deformation in the Faraday shield have been obtained under the two cases. They meet the design requirements and provide the theoretical basis for the structural safety evaluation of the Faraday shield. (authors)
Progress in ICRF heating technology and designs for future large tokamak heating systems
International Nuclear Information System (INIS)
Baity, F.W.; Swain, D.W.; Hoffman, D.J.; Becraft, W.R.; Bryan, W.E.; Mayberry, M.J.; Owens, T.L.; Yugo, J.J.
1986-01-01
The problem of advancing the technology of heating with the ion cyclotron range of frequencies (ICRF) for successful application to ignited plasmas is being addressed at Oak Ridge National Laboratory (ORNL) with the collaboration of several laboratories in the United States and Europe. The needs of experiments such as the Compact Ignition Tokamak (CIT) have been evaluated and conceptual approaches identified. These concepts and their components are examined in the laboratory and applied to present-day machines. The status of this program is presented
15-MeV proton emission from ICRF-heated plasmas
Energy Technology Data Exchange (ETDEWEB)
Jarvis, O.N.; Conroy, S.W.; Hone, M.; Sadler, G.J.; Belle, P. van [Commission of the European Communities, Abingdon (United Kingdom). JET Joint Undertaking
1994-12-31
{sup 3}He-d fusion reaction protons emitted from ICRF-heated discharges were recorded with a silicon diode detector installed in the Joint European Torus (JET). The detection rates demonstrated that sawtooth crashes eject fast particles from the inner region of the plasma. The energy spectra of the fusion product protons using H minority provided evidence for the second harmonic acceleration of deuterons at sub-MW levels of RF power and those with {sup 3}He minority did not possess the expected twin-lobed shape predicted by kinematics calculations. (author) 5 refs., 6 figs.
Finite-element-analysis of fields radiated from ICRF antenna
International Nuclear Information System (INIS)
Yamanaka, Kaoru; Sugihara, Ryo.
1984-04-01
In several simple geometries, electromagnetic fields radiated from a loop antenna, on which a current oscillately flows across the static magnetic field B-vector 0 , are calculated by the finite element method (FEM) as well as by analytic methods in a cross section of a plasma cylinder. A finite wave number along B-vector 0 is assumed. Good agreement between FEM and the analytic solutions is obtained, which indicates the accuracy of FEM solutions. The method is applied to calculations of fields from a half-turn antenna and reasonable results are obtained. It is found that a straightforward application of FEM to problems in an anisotropic medium may bring about erroneous results and that an appropriate coordinate transformation is needed for FEM to become applicable. (author)
International Nuclear Information System (INIS)
Medley, S.S.
1981-07-01
The Charge Exchange Neutral Analyzer (CENA) for TFTR is designed to measure singly charged ion species of atomic mass A = 1, 2, and 3 simultaneously with up to 75 energy channels per mass and an energy range of 0.5 3 charge exchange neutrals makes the analyzer of particular interest for recently proposed fast He 3 ++ diagnostics during ICRF heating on PLT
Numerical modelling of ICRF physics experiments in the Alcator C-mod tokamak
International Nuclear Information System (INIS)
Bonoli, P.T.; Boivin, R.L.; Brambilla, M.
2001-01-01
A full-wave spectral code (TORIC) has been used to simulate mode converted ion Bernstein wave (IBW) propagation and absorption for the first time at high poloidal mode number (-80< m<+80). Converged wave solutions for the mode converted wave are obtained in this limit and the predicted electron damping of the IBW is found to be consistent with experimental measurements from the Alcator C-Mod tokamak. The TORIC code has also been coupled to a bounce-averaged Fokker Planck module FPPRF and the combined codes are now run within the transport analysis tool TRANSP. This model was used to analyze off-axis hydrogen minority heating experiments in C-Mod where an internal transport barrier was obtained. (author)
Theoretical study for ICRF sustained LHD type p-11B reactor
International Nuclear Information System (INIS)
Watanabe, Tsuguhiro
2003-04-01
This is a summary of the workshop on 'Theoretical Study for ICRF Sustained LHD Type p- 11 B Reactor' held in National Institute for Fusion Science (NIFS) on July 25, 2002. In the workshop, study of LHD type D- 3 He reactor is also reported. A review concerning the advanced nuclear fusion fuels is also attached. This review was reported at the workshop of last year. The development of the p- 11 B reactor research which uses the LHD magnetic field configuration has been briefly summarized in section 1. In section 2, an integrated report on advanced nuclear fusion fuels is given. Ignition conditions in a D- 3 He helical reactor are summarized in section 3. 0-dimensional particle and power balance equations are solved numerically assuming the ISS95 confinement law including a confinement factor (γ HH ). It is shown that high average beta plasma confinement, a large confinement factor (γ HH > 3) and the hot ion mode (T i /T e > 1.4) are necessary to achieve the ignition of the D- 3 He helical reactor. Characteristics of ICRF sustained p- 11 B reactor are analyzed in section 4. The nuclear fusion reaction rate is derived assuming a quasilinear plateau distribution function (QPDF) for protons, and an ignition condition of p- 11 B reactor is shown to be possible. The 3 of the presented papers are indexed individually. (J.P.N.)
Modeling ambipolar potential formation due to ICRF heating effects on electrons
International Nuclear Information System (INIS)
Johnson, J.W.; Callen, J.D.; Hershkowitz, N.
1985-08-01
A mechanism for the potential bump observed near the region of ICRF heating in the endplugs of the Phaedrus tandem mirror experiment is investigated by numerical simulation of electron orbits in a simple mirror geometry. Given initial magnetic and ambipolar potential wells that trap the electrons, the ''near field'' parallel electric field E-tilde/sub z/e/sup -iωt/, which is localized near and due to the ICRF heating, tends to eject electrons from the region where E-tilde/sub z/ is nonzero. This depletion of the local electron population causes a local increase in the ambipolar potential. The rate at which the electrons are ejected, (dn/dt), is calculated from the electron orbit computation for a given potential well depth. The rate at which passing particles ''fill in'' the potential well can also be calculated. An estimate of how large the bump in the ambipolar potential becomes is obtained by finding the well depth at which (dn/dt) approximately equals the ''filling'' rate. For Phaedrus parameters (n 0 approx. = 4.0 x 10 12 cm -3 , T/sub e/ = 20 eV, E-tilde/sub z/ approx. = 1.0 V/cm) the electron pumping rate balances the ''filling'' rate at a potential well depth of approximately 40 V, consistent with experimental results
Status of R&D activity for ITER ICRF power source system
International Nuclear Information System (INIS)
Mukherjee, Aparajita; Trivedi, Rajesh; Singh, Raghuraj; Rajnish, Kumar; Machchhar, Harsha; Ajesh, P.; Suthar, Gajendra; Soni, Dipal; Patel, Manoj; Mohan, Kartik; Hari, J.V.S.; Anand, Rohit; Verma, Sriprakash; Agarwal, Rohit; Jha, Akhil; Kazarian, Fabienne; Beaumont, Bertrand
2015-01-01
Highlights: • R&D program to establish high power RF technology for ITER ICRF source is described. • R&D RF source is being developed using Diacrode & Tetrode technologies. • Test rig (3 MW/3600 s/35–65 MHz) simulating plasma load is developed. - Abstract: India is in-charge for the procurement of ITER Ion Cyclotron Resonance Frequency (ICRF) sources (1 Prototype + 8 series units) along with auxiliary power supplies and Local Control Unit. As there is no unique amplifier chain able to meet the output power specifications as per ITER requirement (2.5 MW per source at 35–65 MHz/CW/VSWR 2.0), two parallel three-stage amplifier chains along with a combiner circuit on the output side is considered. This kind of RF source will be unique in terms of its stringent specifications and building a first of its kind is always a challenge. An R&D phase has been initiated for establishing the technology considering single amplifier chain experimentation (1.5 MW/35–65 MHz/3600 s/VSWR 2.0) prior to Prototype and series production. This paper presents the status of R&D activity to resolve technological challenges involved and various infrastructures developed at ITER-India lab to support such operation.
2-D mapping of ICRF-induced SOL perturbations in Tore Supra tokamak
International Nuclear Information System (INIS)
Colas, L.; Gunn, J.P.; Nanobashvili, I.; Petrzilka, V.; Goniche, M.; Ekedahl, A.; Heuraux, S.; Joffrin, E.; Saint-Laurent, F.; Balorin, C.; Lowry, C.; Basiuk, V.
2007-01-01
ICRF-induced SOL modifications are mapped for the first time in 2-D around Tore Supra ICRF antennas using reciprocating Langmuir probes. When probe heads are magnetically connected to powered antennas, radical modifications of floating potentials V float , effective temperatures T eff and ion saturation currents are observed. V float perturbations are located radially near antenna limiters, with a typical extension 2 cm. Poloidally they are locally minimal near the equatorial plane, and maximal near antenna box corners. Two possible interpretations for increased T eff are proposed: localised electron heating and RF loop voltage induced along probe circuit. Both interpretations rely on the generation of parallel RF fields by parallel RF currents on the antenna structure. The topology of such currents could explain the 2-D structure of T eff maps. Both interpretations also imply a positive DC biasing of the antenna environment. Differential biasing of nearby flux tubes drives DC E x B 0 convection that could explain 2-D density patterns
Development of Tokamak experiment technology - Study of ICRF coupling in the KAIST tokamak plasma
Energy Technology Data Exchange (ETDEWEB)
Choi, Duk In; Chang, Hang Young; Lee, Soon Chil; Kwon, Gi Chung; Seo, Sung Hun; Jeon, Sang Jin; Heo, Sung Hee; Heo, Eun Gi; Lee, Dae Hang; Lee, Chan Hee [Korea Advanced Institute of Science and Technology, Taejon (Korea, Republic of)
1995-08-01
Research objectives are to design and fabricate antenna, measure the property of absorption transmitted to the plasma, and research the physical phenomena about the ICRF coupling. Main heating method is ohmic heating at the KAIST tokamak. So, the plasma current produced is more than 30 kA and, the loop voltage of the plasma is 2 {approx} 3V. The power of the plasma by ohmic heating is about 100 kW. Because the toroidal field is 5 {approx} 8 kG, it is needed RF system with more than 100 kW in 7 {approx} 15 MHz. In the first year a RF amplifier with 1 kW in 300 khz {approx} 35 MHz was bought. The manufacture of ICRF system will start from next years. In the research on antenna, we study the method how to measure electric field emitted from antenna using piezo elements. Experimentally, we obtain the results that the signal of piezo element is proportional to the square of electric field. In the next year, we will research the type of antenna subsequently. 28 refs., 3 tabs., 18 figs. (author)
Status of R&D activity for ITER ICRF power source system
Energy Technology Data Exchange (ETDEWEB)
Mukherjee, Aparajita, E-mail: aparajita.mukherjee@iter-india.org [ITER-India, Institute for Plasma Research, Bhat, Gandhinagar–382428 (India); Trivedi, Rajesh; Singh, Raghuraj; Rajnish, Kumar; Machchhar, Harsha; Ajesh, P.; Suthar, Gajendra; Soni, Dipal; Patel, Manoj; Mohan, Kartik; Hari, J.V.S.; Anand, Rohit; Verma, Sriprakash; Agarwal, Rohit; Jha, Akhil [ITER-India, Institute for Plasma Research, Bhat, Gandhinagar–382428 (India); Kazarian, Fabienne; Beaumont, Bertrand [ITER Organization, CS 90 046, 13067 Sain-Paul-Les-Durance (France)
2015-10-15
Highlights: • R&D program to establish high power RF technology for ITER ICRF source is described. • R&D RF source is being developed using Diacrode & Tetrode technologies. • Test rig (3 MW/3600 s/35–65 MHz) simulating plasma load is developed. - Abstract: India is in-charge for the procurement of ITER Ion Cyclotron Resonance Frequency (ICRF) sources (1 Prototype + 8 series units) along with auxiliary power supplies and Local Control Unit. As there is no unique amplifier chain able to meet the output power specifications as per ITER requirement (2.5 MW per source at 35–65 MHz/CW/VSWR 2.0), two parallel three-stage amplifier chains along with a combiner circuit on the output side is considered. This kind of RF source will be unique in terms of its stringent specifications and building a first of its kind is always a challenge. An R&D phase has been initiated for establishing the technology considering single amplifier chain experimentation (1.5 MW/35–65 MHz/3600 s/VSWR 2.0) prior to Prototype and series production. This paper presents the status of R&D activity to resolve technological challenges involved and various infrastructures developed at ITER-India lab to support such operation.
The Ion Cyclotron, Lower Hybrid, and Alfven Wave Heating Methods
International Nuclear Information System (INIS)
Koch, R.
2004-01-01
This lecture covers the practical features and experimental results of the three heating methods. The emphasis is on ion cyclotron heating. First, we briefly come back to the main non-collisional heating mechanisms and to the particular features of the quasilinear coefficient in the ion cyclotron range of frequencies (ICRF). The specific case of the ion-ion hybrid resonance is treated, as well as the polarisation issue and minority heating scheme. The various ICRF scenarios are reviewed. The experimental applications of ion cyclotron resonance heating (ICRH) systems are outlined. Then, the lower hybrid and Alfven wave heating and current drive experimental results are covered more briefly. Where applicable, the prospects for ITER are commented
INTERACTION OF NEUTRAL BEAM INJECTED FAST IONS WITH ION CYCLOTRON RESONANCE FREQUENCY WAVES
International Nuclear Information System (INIS)
CHOI, M.; CHAN, V.S.; CHIU, S.C.; OMELCHENKO, Y.A.; SENTOKU, Y.; STJOH, H.E.
2003-01-01
OAK B202 INTERACTION OF NEUTRAL BEAM INJECTED FAST IONS WITH CYCLOTRON RESONANCE FREQUENCY WAVES. Existing tokamaks such as DIII-D and future experiments like ITER employ both NB injection (NBI) and ion-cyclotron resonance heating (ICRH) for auxiliary heating and current drive. The presence of energetic particles produced by NBI can result in absorption of the Ion cyclotron radio frequency (ICRF) power. ICRF can also interact with the energetic beam ions to alter the characteristics of NBI momentum deposition and resultant impact on current drive and plasma rotation. To study the synergism between NBI and ICRF, a simple physical model for the slowing-down of NB injected fast ions is implemented in a Monte-Carlo rf orbit code. This paper presents the first results. The velocity space distributions of energetic ions generated by ICRF and NBI are calculated and compared. The change in mechanical momentum of the beam and an estimate of its impact on the NB-driven current are presented and compared with ONETWO simulation results
International Nuclear Information System (INIS)
Intrator, T.; Meassick, S.; Browning, J.; Majeski, R.; Ferron, J.R.; Hershkowitz, N.
1989-01-01
It is shown that the predictions of a numerical code (ANTENA) and the data of wave field measurements in the Phaedrus-B tandem mirror are consistent (±25%) for right-handed (B-vector - ) wave fields and less so (±40%) for left-handed (B-vector + ) wave fields in the plasma core, and that they disagree for B-vector + fields near the column edge. Shorting out or reduction of the wave azimuthal electric fields by limiters is the probable cause of this discrepancy. The ICRF fluctuating wave B-vector fields are shown as |B-vector| contour maps in the r-z plane, where the B-vector + data peak at a smaller radius than predicted. The waves are characterized by different dominant axial wave numbers for the left- and right-handed circularly polarized fields. (author). 28 refs, 20 figs, 1 tab
International Nuclear Information System (INIS)
Agnani, Jean-Benoit; DORe, Jean-Francois; Behar-Cohen, Francine; Ducimetiere, Pierre; Le Drean, Yves; Letertre, Thierry; Ndagijimana, Fabien; Sicard, Yves; Hours, Martine; Bertho, Jean-Marc; Cesarini, Jean-Pierre; Couturier, Frederic; EL Khatib, Aicha; Feltin, Nicolas; Flahaut, Emmanuel; Gaffet, Eric; Muzet, Alain; Lafaye, Murielle; Lepoutre, Philippe; Martinsons, Christophe; Mouneyrac, Catherine; Sicard, Yves; Soyez, Alain; Toppila, Esko; Yardin, Catherine; Fite, Johanna; Merckel, Olivier; Saddoki, Sophia
2012-07-01
Eqo is a detection scanner portal used in airports for the detection of various materials on passengers. After a presentation of the context, scope and modalities of this expertise, this report presents the Eqo portal (main actors, operation, physical parameters, obtained image, control capacity, uses) and reports the assessment of the levels of electromagnetic fields emitted by this portal (measurement conditions and measurement devices, results in terms of frequency spectrum, time variations and power density) and the assessment of the exposure to millimetre-wavelength waves in relationship with the use of the Eqo portal (passengers, workers in the airports and airline personnel, operators). Then, it addresses the case of waves with a frequency higher than 1 GHz (potential biological and health effects, depth of penetration, biological studies, and epidemiological studies). The last part proposes an assessment of health risks related to the use of the Eqo portal
Energy Technology Data Exchange (ETDEWEB)
Jezzine, K
2006-11-15
Tools for simulating nondestructive tests by elastic guided waves are developed. Two overall formulations based on modal formalism and reciprocity are derived depending on whether transmission and reception are separated or not. They relate phenomena of guided wave radiation by a transducer, their propagation, their scattering by a non-uniformity of the guide or a defect and their reception. Receiver electrical output is expressed as a product of terms relating to each phenomenon that can be computed separately. Their computation uses developments based on the semi-analytical finite elements method, dealing with guides of arbitrary cross-section and cracks normal to the guide axis. Simulation tools are used to study means for selecting a single mode using a transducer positioned on the guide section, such a selection making easier the interpretation of the results of testing by guided waves. Two methods of mode selection are proposed, based on the use of two specific frequencies (which existence depends on guide geometry and mode symmetry). Mimicking the normal stress distribution of the mode at one of these two frequencies or the other makes it possible to radiate solely or predominantly the mode chosen. Examinations are simulated in configurations using a single or two separated transducers positioned on the section of various guide geometries and cracks of various shapes. The interest and performances of the two methods of mode selection are studied in these configurations. (author)
Bootstrap and fast wave current drive for tokamak reactors
International Nuclear Information System (INIS)
Ehst, D.A.
1991-09-01
Using the multi-species neoclassical treatment of Hirshman and Sigmar we study steady state bootstrap equilibria with seed currents provided by low frequency (ICRF) fast waves and with additional surface current density driven by lower hybrid waves. This study applies to reactor plasmas of arbitrary aspect ratio. IN one limit the bootstrap component can supply nearly the total equilibrium current with minimal driving power ( o = 18 MA needs P FW = 15 MW, P LH = 75 MW). A computational survey of bootstrap fraction and current drive efficiency is presented. 11 refs., 8 figs
Observation of Electron Energy Pinch in HT-7 ICRF Heated Plasmas
International Nuclear Information System (INIS)
Ding Siye; Wan Baonian; Ti Ang; Zhang Xinjun; Liu Zixi; Qian Jinping; Zhong Guoqiang; Duan Yanmin; Wang Lu
2014-01-01
Inward energy transport (pinch phenomenon) in the electron channel is observed in HT-7 plasmas using off-axis ion cyclotron resonance frequency (ICRF) heating. Experimental results and power balance transport analysis by TRANSP code are presented in this article. With the aids of GLF23 and Chang-Hinton transport models, which predict energy diffusivity in experimental conditions, the estimated electron pinch velocity is obtained by experimental data and is found reasonably comparable to the results in the previous study, such as Song on Tore Supra. Density scanning shows that the energy convective velocity in the electron channel has a close relation to density scale length, which is qualitatively in agreement with Wang's theoretical prediction. The parametric dependence of electron energy convective velocity on plasma current is still ambiguous and is worthy of future research on EAST. (magnetically confined plasma)
International Nuclear Information System (INIS)
Bures, M.; Bhatnagar, V.; Cotrell, G.; Corti, S.; Christiansen, J.P.; Hellsten, T.; Jacquinot, J.; Lallia, P.; Lomas, P.; O'Rourke, J.; Taroni, A.; Tibone, F.; Start, D.F.H.
1989-01-01
The performance of high current discharges can be increased by applying central ICRF heating before or shortly after the onset of sawtooth activity in the plasma current rise phase. Sawtooth-free periods have been obtained resulting in the enhanced discharge performance. High T e (0) 9 - 10.5 keV with peaked profiles T e (0)/ e > = 3 - 4 were obtained giving values of n e (0)T e (0) up to 6x10 20 (keV m -3 ). Improvements in T i (0) and neutron production are observed. A 60 % enhancement in D-D reaction rate from 2nd harmonic deuterium (2ω CD ) heating appears to be present. In all current rise (CR) discharges radiation amounts to 25-50 % of total power. (author) 4 refs., 6 figs
International Nuclear Information System (INIS)
Li Jiangang; Zhao Yan Ping; Gu Xue Mao
1999-01-01
A new technique for wall conditioning that will be especially useful for future larger superconducting tokamaks, such as ITER, has been successfully developed and encouraging results have been obtained. Solid carborane powder, which is non-toxic and non-explosive, was used. Pulsed RF plasma was produced by a non-Faraday shielding RF antenna with RF power of 10 kW. The ion temperature was about 2 keV with a toroidal magnetic field of 1.8 T and a pressure of 3x10 -1 Pa. Energetic ions broke up the carborane molecules, and the resulting boron ions struck and were deposited on the first wall. In comparison with glow discharge cleaning boronization, the B/C coating film shows higher adhesion, more uniformity and longer lifetime during plasma discharges. The plasma performance was improved after ICRF boronization. (author). Letter-to-the-editor
A portable data acquisition system on J.I.P.P. T-II ICRF experiment
International Nuclear Information System (INIS)
Hidekuma, S.
1982-03-01
This system has been developed for the data acquisition in the J.I.P.P. T-II ICRF experiment. It is composed of the LSI-11/2(56KB), a dual floppy disk drive, CAMAC modules, a graphic display and an interface module to the HITAC 10-II system. The operating system is RT-11. This system has functions of the data acquisition through A-D converters (max.32ch), the transfer of the data to the HITAC 10-II system and the preservation of them in its floppy disk. Furthermore, a user can easily develop his application programs with this system. The operating procedures of this system are described. (author)
Measurements of the loading impedance and field scaling of a cavity ICRF launcher for Big D
International Nuclear Information System (INIS)
Rettig, C.; Ryan, P.M.; Hoffman, D.J.
1985-01-01
Recently, a new ICRF launcher in the form of a resonant coil cavity has been proposed and analyzed using a convenient two-dimensional model and a Poisson-solver computer code. Here, a physical model of the launcher has been fabricated to test the scaling characteristics of the impedance and relative fields as a function of the physical sizing of the structure. Variable parameters include the antenna-to-plasma distance, the cavity back wall-to-plasma distance, and the antenna cross-sectional shape. Each of these parameters is varied in the interest of optimizing the radiated power for given antenna voltage and current limits. Critical design criterial will be determined from the data. The report consists of 21 viewgraphs
International Nuclear Information System (INIS)
King, J.F.; Baity, F.W.; Hoffman, D.J.; Walls, J.C.; Taylor, D.J.
1988-01-01
The ion cyclotron resonant frequency (ICRF) antennas for heating fusion plasmas require careful analysis of the materials selected for the design and the successful fabrication of high integrity braze bonds. Graphite tiles are brazed to Inconel 625 Faraday shield tubes to protect the antenna from the plasma. The bond between the graphite and Inconel tube is difficult to achieve due to the different coefficients of thermal expansion. A 2-D stress analysis showed the graphite could be bonded to Inconel with a Ag-Cu-Ti braze alloy without cracking the graphite. Brazing procedures and nondestructive examination methods have been developed for these joints. This paper presents the results of our joining development and proof testing. 2 refs., 3 figs
Joule loss on a Faraday shield of JT-60 ICRF test antenna
International Nuclear Information System (INIS)
Fujii, Tsuneyuki; Saigusa, Mikio; Ikeda, Yoshitaka; Kimura, Haruyuki; Hirashima, Teruhisa; Uehara, Munenori.
1988-01-01
Joule loss on a Faraday shield of JT-60 ICRF test antenna with a conductive casing is investigated at the frequency range of 120 MHz. The magnetic field radiated from the antenna is measured by three-dimensionally scanning an rf probe both inside and outside the antenna casing. The magnetic field perpendicular to the Faraday shield, B x , is found to be the largest component near the Faraday shield. It consequently gives the major part of the joule loss on the Faraday shield. The temperature distribution of the Faraday shield due to joule loss is measured directly with a thermocamera. It is confirmed that the area of the high temperature rise is consistent with the peak positions of the B x field. Faraday shield resistance which is estimated from power measurements agrees with the theoretical value. (author)
Calderón Bustillo, Juan; Salemi, Francesco; Dal Canton, Tito; Jani, Karan P.
2018-01-01
The sensitivity of gravitational wave searches for binary black holes is estimated via the injection and posterior recovery of simulated gravitational wave signals in the detector data streams. When a search reports no detections, the estimated sensitivity is then used to place upper limits on the coalescence rate of the target source. In order to obtain correct sensitivity and rate estimates, the injected waveforms must be faithful representations of the real signals. Up to date, however, injected waveforms have neglected radiation modes of order higher than the quadrupole, potentially biasing sensitivity and coalescence rate estimates. In particular, higher-order modes are known to have a large impact in the gravitational waves emitted by intermediate-mass black holes binaries. In this work, we evaluate the impact of this approximation in the context of two search algorithms run by the LIGO Scientific Collaboration in their search for intermediate-mass black hole binaries in the O1 LIGO Science Run data: a matched filter-based pipeline and a coherent unmodeled one. To this end, we estimate the sensitivity of both searches to simulated signals for nonspinning binaries including and omitting higher-order modes. We find that omission of higher-order modes leads to biases in the sensitivity estimates which depend on the masses of the binary, the search algorithm, and the required level of significance for detection. In addition, we compare the sensitivity of the two search algorithms across the studied parameter space. We conclude that the most recent LIGO-Virgo upper limits on the rate of coalescence of intermediate-mass black hole binaries are conservative for the case of highly asymmetric binaries. However, the tightest upper limits, placed for nearly equal-mass sources, remain unchanged due to the small contribution of higher modes to the corresponding sources.
Energy Technology Data Exchange (ETDEWEB)
Titov, O.; Stanford, Laura M. [Geoscience Australia, P.O. Box 378, Canberra, ACT 2601 (Australia); Johnston, Helen M.; Hunstead, Richard W. [Sydney Institute for Astronomy, School of Physics, University of Sydney, NSW 2006 (Australia); Pursimo, T. [Nordic Optical Telescope, Nordic Optical Telescope Apartado 474E-38700 Santa Cruz de La Palma, Santa Cruz de Tenerife (Spain); Jauncey, David L. [CSIRO Astronomy and Space Science, ATNF and Research School of Astronomy and Astrophysics, Australian National University, Canberra, ACT 2611 (Australia); Maslennikov, K. [Central Astronomical Observatory at Pulkovo, Pulkovskoye Shosse, 65/1, 196140, St. Petersburg (Russian Federation); Boldycheva, A., E-mail: oleg.titov@ga.gov.au [Ioffe Physical Technical Institute, 26 Polytekhnicheskaya, St. Petersburg, 194021 (Russian Federation)
2013-07-01
Continuing our program of spectroscopic observations of International Celestial Reference Frame (ICRF) sources, we present redshifts for 120 quasars and radio galaxies. Data were obtained with five telescopes: the 3.58 m European Southern Observatory New Technology Telescope, the two 8.2 m Gemini telescopes, the 2.5 m Nordic Optical Telescope (NOT), and the 6.0 m Big Azimuthal Telescope of the Special Astrophysical Observatory in Russia. The targets were selected from the International VLBI Service for Geodesy and Astrometry candidate International Celestial Reference Catalog which forms part of an observational very long baseline interferometry (VLBI) program to strengthen the celestial reference frame. We obtained spectra of the potential optical counterparts of more than 150 compact flat-spectrum radio sources, and measured redshifts of 120 emission-line objects, together with 19 BL Lac objects. These identifications add significantly to the precise radio-optical frame tie to be undertaken by Gaia, due to be launched in 2013, and to the existing data available for analyzing source proper motions over the celestial sphere. We show that the distribution of redshifts for ICRF sources is consistent with the much larger sample drawn from Faint Images of the Radio Sky at Twenty cm (FIRST) and Sloan Digital Sky Survey, implying that the ultra-compact VLBI sources are not distinguished from the overall radio-loud quasar population. In addition, we obtained NOT spectra for five radio sources from the FIRST and NRAO VLA Sky Survey catalogs, selected on the basis of their red colors, which yielded three quasars with z > 4.
SIDON: A simulator of radio-frequency networks. Application to WEST ICRF launchers
Helou, Walid; Dumortier, Pierre; Durodié, Frédéric; Goniche, Marc; Hillairet, Julien; Mollard, Patrick; Berger-By, Gilles; Bernard, Jean-Michel; Colas, Laurent; Lombard, Gilles; Maggiora, Riccardo; Magne, Roland; Milanesio, Daniele; Moreau, Didier
2015-12-01
SIDON (SImulator of raDiO-frequency Networks) is an in-house developed Radio-Frequency (RF) network solver that has been implemented to cross-validate the design of WEST ICRF launchers and simulate their impedance matching algorithm while considering all mutual couplings and asymmetries. In this paper, the authors illustrate the theory of SIDON as well as results of its calculations. The authors have built time-varying plasma scenarios (a sequence of launchers front-faces L-mode and H-mode Z-matrices), where at each time step (1 millisecond here), SIDON solves the RF network. At the same time, when activated, the impedance matching algorithm controls the matching elements (vacuum capacitors) and thus their corresponding S-matrices. Typically a 1-second pulse requires around 10 seconds of computational time on a desktop computer. These tasks can be hardly handled by commercial RF software. This innovative work allows identifying strategies for the launchers future operation while insuring the limitations on the currents, voltages and electric fields, matching and Load-Resilience, as well as the required straps voltage amplitude/phase balance. In this paper, a particular attention is paid to the simulation of the launchers behavior when arcs appear at several locations of their circuits using SIDON calculator. This latter work shall confirm or identify strategies for the arc detection using various RF electrical signals. One shall note that the use of such solvers in not limited to ICRF launchers simulations but can be employed, in principle, to any linear or linearized RF problem.
Theoretical study for ICRF sustained LHD type p-{sup 11}B reactor
Energy Technology Data Exchange (ETDEWEB)
Watanabe, Tsuguhiro (ed.)
2003-04-01
This is a summary of the workshop on 'Theoretical Study for ICRF Sustained LHD Type p-{sup 11}B Reactor' held in National Institute for Fusion Science (NIFS) on July 25, 2002. In the workshop, study of LHD type D-{sup 3}He reactor is also reported. A review concerning the advanced nuclear fusion fuels is also attached. This review was reported at the workshop of last year. The development of the p-{sup 11}B reactor research which uses the LHD magnetic field configuration has been briefly summarized in section 1. In section 2, an integrated report on advanced nuclear fusion fuels is given. Ignition conditions in a D-{sup 3}He helical reactor are summarized in section 3. 0-dimensional particle and power balance equations are solved numerically assuming the ISS95 confinement law including a confinement factor ({gamma}{sub HH}). It is shown that high average beta plasma confinement, a large confinement factor ({gamma}{sub HH} > 3) and the hot ion mode (T{sub i}/T{sub e} > 1.4) are necessary to achieve the ignition of the D-{sup 3}He helical reactor. Characteristics of ICRF sustained p-{sup 11}B reactor are analyzed in section 4. The nuclear fusion reaction rate < {sigma}{upsilon} > is derived assuming a quasilinear plateau distribution function (QPDF) for protons, and an ignition condition of p-{sup 11}B reactor is shown to be possible. The 3 of the presented papers are indexed individually. (J.P.N.)
Optimization of the FAST ICRF antenna using TOPICA code
International Nuclear Information System (INIS)
Sorba, M.; Milanesio, D.; Maggiora, R.; Tuccillo, A.
2010-01-01
Ion Cyclotron Resonance Heating is one of the most important auxiliary heating systems in most plasma confinement experiments. Because of this, the need for very accurate design of ion cyclotron (IC) launchers has dramatically grown in recent years. Furthermore, a reliable simulation tool is a crucial request in the successful design of these antennas, since full testing is impossible outside experiments. One of the most advanced and validated simulation codes is TOPICA, which offers the possibility to handle the geometrical level of detail of a real antenna in front of an accurately described plasma scenario. Adopting this essential tool made possible to reach a refined design of ion cyclotron radio frequency antenna for the FAST (Fusion Advanced Studies Torus) experiment . Starting from a streamlined antenna model and then following well-defined refinement procedures, an optimized launcher design in terms of power delivered to plasma has been finally achieved. The computer-assisted geometry refinements allowed an increase in the performances of the antenna and notably in power handling: the extent of the gained improvements were not experienced in the past, essentially due to the absence of predictive tools capable of analyzing the detailed effects of antenna geometry in plasma facing conditions. Thus, with the help of TOPICA code, it has been possible to comply with the FAST experiment requirements in terms of vacuum chamber constraints and power delivered to plasma. Once an antenna geometry was optimized with a reference plasma profile, the analysis of the performances of the launcher has been extended with respect to two plasma scenarios. Exploiting all TOPICA features, it has been possible to predict the behavior of the launcher in real operating conditions, for instance varying the position of the separatrix surface. In order to fulfil the analysis of the FAST IC antenna, the study of the RF potentials, which depend on the parallel electric field computation
Talukdar, Karabi; Behera, Laxmidhar
2018-03-01
Imaging below the basalt for hydrocarbon exploration is a global problem because of poor penetration and significant loss of seismic energy due to scattering, attenuation, absorption and mode-conversion when the seismic waves encounter a highly heterogeneous and rugose basalt layer. The conventional (short offset) seismic data acquisition, processing and modeling techniques adopted by the oil industry generally fails to image hydrocarbon-bearing sub-trappean Mesozoic sediments hidden below the basalt and is considered as a serious problem for hydrocarbon exploration in the world. To overcome this difficulty of sub-basalt imaging, we have generated dense synthetic seismic data with the help of elastic finite-difference full-wave modeling using staggered-grid scheme for the model derived from ray-trace inversion using sparse wide-angle seismic data acquired along Sinor-Valod profile in the Deccan Volcanic Province of India. The full-wave synthetic seismic data generated have been processed and imaged using conventional seismic data processing technique with Kirchhoff pre-stack time and depth migrations. The seismic image obtained correlates with all the structural features of the model obtained through ray-trace inversion of wide-angle seismic data, validating the effectiveness of robust elastic finite-difference full-wave modeling approach for imaging below thick basalts. Using the full-wave modeling also allows us to decipher small-scale heterogeneities imposed in the model as a measure of the rugose basalt interfaces, which could not be dealt with ray-trace inversion. Furthermore, we were able to accurately image thin low-velocity hydrocarbon-bearing Mesozoic sediments sandwiched between and hidden below two thick sequences of high-velocity basalt layers lying above the basement.
International Nuclear Information System (INIS)
Wauters, T.
2011-11-01
This work is devoted to the study and optimization of the Ion Cyclotron Wall Conditioning (ICWC) technique. ICWC, operated in presence of the toroidal magnetic field, makes use of four main tokamak systems: the ICRF antennas to initiate and sustain the conditioning discharge, the gas injection valves to provide the discharge gas, the machine pumps to remove the wall desorbed particles, and the poloidal magnetic field system to optimize the discharge homogeneity. Additionally neutral gas and plasma diagnostics are required to monitor the discharge and the conditioning efficiency. In chapter 2 a general overview on ICWC is given. Chapter 3 treats the ICRF discharge homogeneity and the confinement properties of the employed magnetic field. In the first part we will discuss experimental facts on plasma homogeneity, and how experimental optimization led to its improvement. In the second part of the chapter the confinement properties of a partially ionized plasma in a toroidal magnetic field configuration with additional small vertical component are discussed. Chapter 4 gives an overview of experimental results on the efficiency of ICWC, obtained on TORE SUPRA, TEXTOR, JET and ASDEX Upgrade. In chapter 5 a 0D kinetic description of hydrogen-helium RF plasmas is outlined. The model, describing the evolution of ICRF plasmas from discharge initiation to the (quasi) steady state plasma stage, is developed to obtain insight on ICRF plasma parameters, particle fluxes to the walls and the main collisional processes. Chapter 6 presents a minimum structure for a 0D reservoir model of the wall to investigate in deeper detail the ICWC plasma wall interaction during isotopic exchange experiments. The hypothesis used to build up the wall model is that the same model structure should be able to describe the wall behavior during normal plasmas and conditioning procedures. Chapter 7 extrapolates the results to the envisaged application of ICWC on ITER
DEFF Research Database (Denmark)
Martin, E.; Thougaard, A.V.; Grauslund, M.
2009-01-01
of topoisomerase II, resulting in the risk of additional myelosuppression in patients receiving ICRF-187 as a cardioprotectant in combination with doxorubicin. The development of a topoisomerase II-inactive iron chelating compound thus appeared attractive. In the present paper we evaluate the topoisomerase II...... chelation alone does not appear to be sufficient for protection against anthracycline-induced cardiomyopathy Udgivelsesdato: 2009/1/8...
International Nuclear Information System (INIS)
Shoji, Mamoru; Kasahara, Hiroshi; Tanaka, Hirohiko
2015-01-01
The termination process of long pulse plasma discharges in the Large Helical Device (LHD) have been observed with fast framing cameras, which shows that the reason for the termination of the discharged has been changed with increased plasma heating power, improvements of plasma heating systems and change of the divertor configuration, etc. For long pulse discharges in FYs2010-2012, the main reason triggering the plasma termination was reduction of ICRF heating power with rise of iron ion emission due to electric breakdown in an ICRF antenna. In the experimental campaign in FY2013, the duration time of ICRF heated long pulse plasma discharges has been extended to about 48 minutes with a plasma heating power of ∼1.2 MW and a line-averaged electron density of ∼1.2 × 10"1"9 m"-"3. The termination of the discharges was triggered by release of large amounts of carbon dusts from closed divertor regions, indicating that the control of dust formation in the divertor regions is indispensable for extending the duration time of long pulse discharges. (author)
Directory of Open Access Journals (Sweden)
Mari J. L.
2006-11-01
Full Text Available Les enregistrements des données acoustiques en champ total (fuit waveform ont conduit le géophysicien et le diagraphiste à utiliser des techniques de traitement du signal pour séparer les différentes ondes observées sur les enregistrements. L'une des tâches importantes du traitement des diagraphies acoustiques est le pointé des temps d'arrivée des différentes ondes enregistrées. Une démarche de type système expert a été utilisée pour mettre au point un algorithme multicanaux qui réalise le pointé des différentes ondes, à l'aide de règles faisant intervenir les caractéristiques ou attributs de chaque onde. Une onde est caractérisée par sa vitesse, sa fréquence, son amplitude et sa cohérence latérale. L'algorithme fournit un ensemble de logs accompagnés d'une estimation de la dispersion des mesures à chaque cote profondeur. Les logs fournis sont les logs de lenteur et les logs de fréquence. Les résultats obtenus sur un ensemble de diagraphies acoustiques enregistrées dans un puits vertical du Bassin parisien montrent que la dispersion des mesures reste faible en comparaison des pas d'échantillonnage en temps et profondeur. Les logs de dispersion peuvent aussi permettre de détecter des phénomènes physiques tels que caves, fractures, conversions d'ondes ou interférences, reliés à la lithologie. Dans une deuxième partie, nous montrerons différentes techniques de séparation d'ondes. La troisième partie illustrera, sur un cas particulier, l'utilisation des logs issus des diagraphies acoustiques pour caractériser les formations. The full waveforms recorded by an array of recievers in a borehole sonic tool contain a set of waves that can be fruitfully used to obtain detailed information about the nearborehole lithology and structure. The different waves that can be observed by full-waveform sonic data are described in this article. The main tools used in the recording of full-waveform data are then reviewed
International Nuclear Information System (INIS)
Mascali, D.; Neri, L.; Castro, G.; Celona, L.; Gammino, S.; Torrisi, G.; Sorbello, G.
2015-01-01
Electron Cyclotron Resonance (ECR) ion Sources are the most performing machines for the production of intense beams of multi-charged ions in fundamental science, applied physics and industry. Investigation of plasma dynamics in ECRIS still remains a challenge. A better comprehension of electron heating, ionization and diffusion processes, ion confinement and ion beam formation is mandatory in order to increase ECRIS performances both in terms of output beams currents, charge states, beam quality (emittance minimization, beam halos suppression, etc.). Numerical solution of Vlasov equation via kinetic codes coupled to FEM solvers is ongoing at INFN-LNS, based on a PIC strategy. Preliminary results of the modeling will be shown about wave-plasma interaction and electron-ion confinement: the obtained results are very helpful to better understand the influence of the different parameters (especially RF frequency and power) on the ion beam formation mechanism. The most important clues coming out from the simulations are that although vacuum field RF field distribution (that is a cavity, modal field distribution) is perturbed by the plasma medium, the non-uniformity in the electric field amplitude still persists in the plasma filled cavity. This non-uniformity can be correlated with non-uniform plasma distribution, explaining a number of experimental observations
2015-10-30
Coastal Inlets Research Program CMS -Wave CMS -Wave is a two-dimensional spectral wind-wave generation and transformation model that employs a forward...marching, finite-difference method to solve the wave action conservation equation. Capabilities of CMS -Wave include wave shoaling, refraction... CMS -Wave can be used in either on a half- or full-plane mode, with primary waves propagating from the seaward boundary toward shore. It can
Mengxuan, Zhong; Jun, Tan; Peng, Song; Xiao-bo, Zhang; Chuang, Xie; Zhao-lun, Liu
2017-01-01
The gradient preconditioning algorithms based on Hessian matrices in time-domain full waveform inversion (FWI) are widely used now, but consume a lot of memory and do not fit the FWI of large models or actual seismic data well. To avoid the huge
Upgrades to the 4-strap ICRF Antenna in Alcator C-Mod
International Nuclear Information System (INIS)
G. Schilling; J.C. Hosea; J.R. Wilson; W. Beck; R.L. Boivin; P.T. Bonoli; D. Gwinn; W.D. Lee; E. Nelson-Melby; M. Porkolab; R. Vieira; S.J. Wukitch; J.A. Goetz
2001-01-01
A 4-strap ICRF antenna suitable for plasma heating and current drive has been designed and fabricated for the Alcator C-Mod tokamak. Initial operation in plasma was limited by high metallic impurity injection resulting from front surface arcing between protection tiles and from current straps to Faraday shields. Antenna modifications were made in February 2000, resulting in impurity reduction, but low-heating efficiency was observed when the antenna was operated in its 4-strap rather than a 2-strap configuration. Further modifications were made in July 2000, with the installation of BN plasma-facing tiles and radio- frequency bypassing of the antenna backplane edges and ends to reduce potential leakage coupling to plasma surface modes. Good heating efficiency was now observed in both heating configurations, but coupled power was limited to 2.5 MW in H-mode, 3 MW in L-mode, by plasma-wall interactions. Additional modifications were started in February 2001 and will be completed by this meeting. All the above upgrades and their effect on antenna performance will be presented
RF-sheath assessment of ICRF antenna geometry for long pulses
International Nuclear Information System (INIS)
Colas, L.; Bremond, S.
2003-01-01
Monitoring powered ion cyclotron resonance frequency (ICRF) antennas in magnetic fusion devices has revealed localized modifications of the plasma edge in the antenna shadow, most of them probably related to an enhanced polarization of the scrape-off layer (SOL) through radio-frequency (RF) sheath rectification. Although tolerable on present short RF pulses, sheaths should be minimized, as they may hinder proper operation of steady-state antennas and other subsystems connected magnetically to them, such as lower hybrid grills. As a first step towards mitigating RF sheaths in the design of future antennas, the present paper analyses the spatial structure of sheath potential maps in their vicinity, in relation with the 3D topology of RF near fields and the geometry of antenna front faces. Various combinations of poloidal radiating straps are first considered, and results are confronted to those inferred from transmission line theory. The dependence of sheath potentials on RF voltages or RF currents is studied. The role of RF near-field symmetries along tilted field lines is stressed to interpret such effects as that of strap phasing. A generalization of the 'dipole effect' is proposed. With similar arguments, the behavior of Faraday screen corners, where hot spots concentrate on Tore-Supra (TS), is then studied. The merits of aligning the antenna structure with the tilted magnetic field are thus discussed. The effect of switching from TS (high RF voltage near corners) to ITER-like electrical configurations of the straps (high voltage near equatorial plane) is also analyzed. (authors)
International Nuclear Information System (INIS)
Bures, M.; Bhatnagar, V.; Christiansen, J.P.
1989-01-01
The performance of high current discharges can be improved by applying central ICRF heating before or shortly after the onset of sawtooth activity in the plasma current rise phase. Long sawtooth-free periods have been obtained which result in a transiently-enhanced discharge performance. High T c (0) = 9-10.5 keV with peaked profile T e (0)/ e > = 3-4 were obtained giving values of N e (0)T e (0) up to 6 x 10 20 (keV m -3 ). Improvements in T i (0) and neutron production are observed. A best value of n Dd (0)T i (0)τ E = 1.65 x 10 20 (m -3 keV s) was achieved. Local transport simulation shows that the electron and ion thermal diffusivities do not differ substantially in the two cases of current-rise (CR) and flat-top (FT) heating, the performance of the central plasma region being enhanced, in the case of current-rise, entirely by the elimination of the sawtooth instability. The maximum D-D reaction rate is enhanced by a factor of 2 compared to the flat-top value. An appreciable part of the reaction rate is attributed to 2nd harmonic deuterium (2ω CD ) heating. In all current-rise discharges radiation amounts to 25-50% of total power and Ζ eff remains roughly constant. (author)
International Nuclear Information System (INIS)
1988-01-01
The Phaedrus Program now consists of two major devices, the Phaedrus-B Tandem mirror and the Phaedrus-T tokamak. Phaedrus-B has been modified to operate as an axisymmetric tandem mirror with no quadrupole end cell fields and only circular baffles. Phaedrus-T is now under construction. The Phaedrus-T vacuum chamber is nearing completion and new toroidal field coils have been ordered (with completion expected in early 1989). As originally proposed, when Phaedrus-T is operational, our initial plan is to continue operating both devices (on alternating schedules). We will utilize the same control room, power supplies, and staff for both devices, and graduate students will have thesis project physics issues that can be studied on both devices. Investigations are currently and, will continue to be, centered around five physics areas. All involve ICRF. These are: edge physics; ponderomotive effects; mode conversion; mode control; and tandem mirror specific. The first four will ultimately involve activities on both Phaedrus-T and Phaedrus-B. The fifth includes work that is specifically related to tandem mirror issues. 4 figs
Analysis of 4-strap ICRF Antenna Performance in Alcator C-Mod
International Nuclear Information System (INIS)
Schilling, G.; Wukitch, S.J.; Boivin, R.L.; Goetz, J.A.; Hosea, J.C.; Irby, J.H.; Lin, Y.; Parisot, A.; Porkolab, M.; Wilson, J.R.
2003-01-01
A 4-strap ICRF antenna was designed and fabricated for plasma heating and current drive in the Alcator C-Mod tokamak. Initial upgrades were carried out in 2000 and 2001, which eliminated surface arcing between the metallic protection tiles and reduced plasma-wall interactions at the antenna front surface. A boron nitride septum was added at the antenna midplane to intersect electric fields resulting from radio-frequency sheath rectification, which eliminated antenna corner heating at high power levels. The current feeds to the radiating straps were reoriented from an E||B to E parallel B geometry, avoiding the empirically observed ∼15 kV/cm field limit and raising antenna voltage holding capability. Further modifications were carried out in 2002 and 2003. These included changes to the antenna current strap, the boron nitride tile mounting geometry, and shielding the BN-metal interface from the plasma. The antenna heating efficiency, power, and voltage characteristics under these various configurations will be presented
Loading, absorption, and Fokker-Planck calculations for upcoming ICRF experiments on ATF
International Nuclear Information System (INIS)
Shepard, T.D.; Carter, M.D.; Goulding, R.H.; Kwon, M.
1989-01-01
ICRF experiments on ATF at the 100-kW level are planned for the current 1989 operating period. These plans include the 2ω/sub cH/ regime at f/sub RF/ = 28.88 MHz, D(H) at 14.44 MHz, and 4 He( 3 He) and D( 3 He) at 9.63 MHz. ECH target plasmas have n/sub eO/ /approxreverse arrowlt/ 0.15 /times/ 10 20 m/sup /minus/3/ and B = 0.95 T. The density and temperature profiles obtained are broader than those from 1988, owing to recent field error corrections. The values used for target-plasma parameters in the calculations were taken from initial 1989 ATF data. Loading and absorption calculations have been performed using the 3D RF heating code ORION with a helically symmetric equilibrium, and Fokker-Planck calculations were performed using the steady-state code RFTRANS with two velocity dimensions and one spatial dimension. 6 refs., 3 figs
A study on the fusion reactor - Study of ICRF coupling in the KAIST tokamak plasma
Energy Technology Data Exchange (ETDEWEB)
Choi, Duk In; Chang, Hong Young; Lee, Sun Chil; Jun, Sang Jin; Kwon, Gi Chung; Seo, Sung Hun; Heo, Sung Hoi; You, Kwang Il; Song, Soo Bin; Lee, Sung Chul; Kim, Min Chul; Lee, Chan Hui [Korea Advanced Institute of Science and Technology, Taejon (Korea, Republic of)
1996-09-01
Research objectives are to design and fabricate the antenna, measure t property of absorption transmitted to the plasma, and research the physical phenomena about the ICRF coupling, Main heating method is ohmic heating at the KAIST tokamak. The power of the plasma produced by ohmic heating is about 100 kW. Because the toroidal field is 5 {approx} 8 kG, the RF system`s output power is about 10 kW and frequency range is 7 {approx} 30 MHz. In the first year, a 1 kW RF preamplifier was bought. In this year, a CW 2 kW RF main amp. and RF power monitoring system was bought. In the research on antenna, we study the method how to measure electric field emitted from antenna using piezo elements. The matching network composed of two VVC (35 kV), 100 {approx} 1000 pF match firmly up to 50 kW power. We studied the measurement method of antenna impedance theoretically, and measured power efficiency and antenna impedance in the helicon plasma. 32 refs., 5 tabs., 29 figs. (author)
Recycling behaviour during long pulse discharges after ICRF boronization in the HT-7 tokamak
International Nuclear Information System (INIS)
Huang, J.; Wan, B.N.; Li, J.G.; Gong, X.Z.; Zhang, X.D.; Wu, Z.W.; Zhou, Q.
2006-01-01
The evolution of recycling behaviour has been investigated during long pulse discharges in the HT-7 tokamak after ICRF boronization (C 2 B 10 H 12 ) using the H/(H+D) ratio and the edge recycling coefficient R. After boronization, impurity reduction is observed, attributed to the fresh boron film, but the recycling coefficient can exceed unity due to a large amount of hydrogen absorbed in the film, leading to an uncontrollable density rise and discharge termination. When the H/(H+D) ratio was reduced to less than 25%, the electron density was easily controlled. The longest discharge, up to 240 s with central electron temperature T e (0) of about 1.0 keV and central electron density n e (0) of 0.8 x 10 19 m -3 , was achieved following boronization. After many discharges the effectiveness of boron film was weakened, and the density rise was correlated with an increase in both carbon and oxygen radiation which limited the duration of long pulse discharges
Modelling of DC electric fields induced by RF sheath in front of ICRF antenna
International Nuclear Information System (INIS)
Faudot, E.; Heuraux, S.; Colas, L.
2003-01-01
Reducing the ICRF (ion cyclotron range frequency) antenna-plasma interaction is one of the key points for reaching very long tokamak discharges. One problem which limits such discharges, is the appearance of hot spots on the surface of the antenna: Radio Frequency (RF) sheaths modify the properties of the edge plasma by rectifying the RF potential along open magnetic field lines and can induce hot spots. This paper investigates the corrections to sheath potentials introduced by the interactions between adjacent flux tubes. Our theoretical study started from an oscillating double Langmuir probe model, in which a transverse influx of current was included. This model was confronted with 1D PIC simulations along a magnetic field line, and demonstrated that current exchanges can decrease mean potentials. A 2D electrostatic fluid code was then developed, which couples adjacent flux tubes in a poloidal cross section with collisional conductivity or polarization currents. It showed that transverse currents are able to smooth structures smaller than a characteristic size in the sheath potential maps (results for Tore Supra). These computed rectified potentials can be used to obtain the DC electric fields in front of the antenna. And then, it gives an estimate of the particle drift and the energy flux on the antenna structure, which can explain hot spots. (author)
VUV study of impurity generation during ICRF heating experiments on the Alcator C tokamak
International Nuclear Information System (INIS)
Manning, H.L.
1986-06-01
A 2.2 meter grazing incidence VUV monochromator has been converted into a time-resolving spectrograph by the addition of a new detector system, based on a microchannel plate image intensifier linked to a 1024-element linear photodiode array. The system covers the wavelength range 15 to 1200 A (typically 40 A at a time) with resolution of up to .3 A FWHM. Time resolution is selectable down to 0.5 msec. The system sensitivity was absolutely calibrated below 150 A by a soft x-ray calibration facility. The spectrograph was installed on the Alcator C tokamak at MIT to monitor plasma impurity emission. There, cross-calibration with a calibrated EUV monochromator was performed above 400 A. Calibration results, system performance characteristics, and data from Alcator C are presented. Observations of impurity behavior are presented from a series of ICRF heating experiments (180 MHz, 50 to 400 kW) performed on the Alcator C tokamak, using graphite limiters and stainless steel antenna Faraday shields
Performance of the JT-60 ICRF antenna with an open type Faraday shield
International Nuclear Information System (INIS)
Fujii, T.; Saigusa, M.; Kimura, H.; Moriyama, S.; Annoh, K.; Kawano, Y.; Kobayashi, N.; Kubo, H.; Nishitani, T.; Ogawa, Y.; Shinozaki, S.; Terakado, M.
1992-01-01
Performance of the JT-60 ICRF antenna in second and third harmonic heating schemes (f=120, 131 MHz) over past four years of operation is presented. The antenna is mainly composed of phased 2x2 loops, an open type Faraday shield and a metallic casing, forming a plug-in type. The antenna is operated for wide plasma parameters: anti n e =1-7x10 19 m -3 , I P =1-2.8 MA and B T =2.2-4.8 T. The open type Faraday shield shows no deterioration for impurity production and heating efficiency up to the maximum injected power of 3.1 MW (the power density of 16 MW/m 2 ) except the following particular condition. Only for (0, 0) phasing and less than 30 mm of the distance between the outermost magnetic surface and the antenna guard limiter, the radiation loss increases abruptly from ΔP rad /P IC ∝0.3 to ΔP rad /P IC ∝4 in carbon limiter discharges when the injected power exceeds a threshold value of ∝0.5 MW. Strong titanium impurity release from the Faraday shield is observed in coincidence with the increase in the radiation loss. This suggests that strong ion sputtering is induced on the Faraday shield by RF sheaths. (orig.)
Directory of Open Access Journals (Sweden)
Qi Zhang
2014-01-01
Full Text Available With the aim to analyze field-to-line coupling effects based on energy spectrum, parallel finite-difference time-domain (FDTD method is applied to calculate the induced voltage on overhead lines under high-power electromagnetic (HPEM environment. Firstly, the energy distribution laws of HEMP (IEC 61000-2-9, HEMP (Bell Laboratory, HEMP (Paulino et al., 2010, and LEMP (IEC61000-4-5 are given. Due to the air-earth stratified medium, both the absorbing boundary and the connecting boundary applied to scattering by finite-length objects are separately set in aerial and underground parts. Moreover, the influence of line length on induced voltage is analyzed and discussed. The results indicate that the half-peak width is wider with the increase of the line length. But the steepness of induced voltage on the overhead line is invariable. There is no further increase in the peak of induced voltage especially when the line length increases to be equivalent to the wavelength of the frequency bands with the maximum energy.
Directory of Open Access Journals (Sweden)
Arne Van Londersele
2017-01-01
Full Text Available Graphene-based electrical components are inherently multiscale, which poses a real challenge for finite-difference time-domain (FDTD solvers due to the stringent time step upper bound. Here, a unidirectionally collocated hybrid implicit-explicit (UCHIE FDTD method is put forward that exploits the planar structure of graphene to increase the time step by implicitizing the critical dimension. The method replaces the traditional Yee discretization by a partially collocated scheme that allows a more accurate numerical description of the material boundaries. Moreover, the UCHIE-FDTD method preserves second-order accuracy even for nonuniform discretization in the direction of collocation. The auxiliary differential equation (ADE approach is used to implement the graphene sheet as a dispersive Drude medium. The finite grid is terminated by a uniaxial perfectly matched layer (UPML to permit open-space simulations. Special care is taken to elaborate on the efficient implementation of the implicit update equations. The UCHIE-FDTD method is validated by computing the shielding effectiveness of a typical graphene sheet.
High field side launch of RF waves: A new approach to reactor actuators
Wallace, G. M.; Baek, S. G.; Bonoli, P. T.; Faust, I. C.; LaBombard, B. L.; Lin, Y.; Mumgaard, R. T.; Parker, R. R.; Shiraiwa, S.; Vieira, R.; Whyte, D. G.; Wukitch, S. J.
2015-12-01
Launching radio frequency (RF) waves from the high field side (HFS) of a tokamak offers significant advantages over low field side (LFS) launch with respect to both wave physics and plasma material interactions (PMI). For lower hybrid (LH) waves, the higher magnetic field opens the window between wave accessibility (n∥≡c k∥/ω >√{1 -ωpi 2/ω2+ωpe 2/ωce 2 }+ωp e/|ωc e| ) and the condition for strong electron Landau damping (n∥˜√{30 /Te } with Te in keV), allowing LH waves from the HFS to penetrate into the core of a burning plasma, while waves launched from the LFS are restricted to the periphery of the plasma. The lower n∥ of waves absorbed at higher Te yields a higher current drive efficiency as well. In the ion cyclotron range of frequencies (ICRF), HFS launch allows for direct access to the mode conversion layer where mode converted waves absorb strongly on thermal electrons and ions, thus avoiding the generation of energetic minority ion tails. The absence of turbulent heat and particle fluxes on the HFS, particularly in double null configuration, makes it the ideal location to minimize PMI damage to the antenna structure. The quiescent SOL also eliminates the need to couple LH waves across a long distance to the separatrix, as the antenna can be located close to plasma without risking damage to the structure. Improved impurity screening on the HFS will help eliminate the long-standing issues of high Z impurity accumulation with ICRF. Looking toward a fusion reactor, the HFS is the only possible location for a plasma-facing RF antenna that will survive long-term. By integrating the antenna into the blanket module it is possible to improve the tritium breeding ratio compared with an antenna occupying an equatorial port plug. Blanket modules will require remote handling of numerous cooling pipes and electrical connections, and the addition of transmission lines will not substantially increase the level of complexity. The obvious engineering
Directory of Open Access Journals (Sweden)
Gavin P.
2006-11-01
'ambiguïté sur l'origine des réflexions. The fule waveforms recorded by an array of receivers in a borehole sonic tool contain a set of waves that can be fruitfully used to obtain detailed information about the nearborehole lithology and structure. Each wave contains information that can be disturbed by the presence of the other waves. The great amount of full-waveform sonic data leads geophysicists and log analysts to implement algorithms for separating waves. The log analyst must pay attention to the choice of parameters for acquisition. The acoustic data must be recorded with well suited spatial and temporal sampling-rates to avoid spatial and temporal aliasings. The efficiency of the wave-separation algorithms depends on the choice of acoustic data gathers. Acoustic data are sorted either in a common-shot gather or in a constant-offset gather. The wave separation filters commonly used are apparent velocity filters. Less usual filters are a Wiener filter and a spectral matrix filter. The efficiency of an apparent velocity filter is enhanced by application of spectrum equalization. The signal to noise ratio is enhanced by spectral matrix filtering. We describe different processing sequences applied to a set of field examples. First field example: full-waveform sonic data in a vertical wellFull-waveform sonic data were acquired in a vertical well drilled in an anticline structure used for underground gas storage by Gaz de France. The sonic tool used was a Schlumberger Dipole Imaging tool. This tool is an eight-receiver/three-transmitter device. The receiver section contains eight dipole-monopole stations spanning 3. 5 ft, each station spaced 6 inches (15 cm from its neighbor. The distance between the monopole transmitter and the first receiver station is 9 ft. The source was fired at equal spacings of 6 inches throughout the open hole section. For this experiment, the monopole transmitter was activated with a low frequency pulse for the purpose of generating low frequency
Energy Technology Data Exchange (ETDEWEB)
Start, D F.H. [Commission of the European Communities, Abingdon (United Kingdom). JET Joint Undertaking; Righi, E [Imperial Coll. of Science and Technology, London (United Kingdom); Warrick, C [UKAEA Culham Lab., Abingdon (United Kingdom)
1994-07-01
A model is presented that can simulate the {gamma} emissivity in the poloidal cross-section during ({sup 3}He)D ICRF heated discharges in JET plasmas, by merging information obtained from the fast ion distribution and from nuclear reactions producing the observed {gamma} emissivity (production of {gamma} photons during {sup 3}He-{sup 9}Be reactions). This technique can play an important role in the identification of plasma instabilities that affect the redistribution of the fast ions in the plasma, like the TAE modes and the ripple in the tokamak magnetic field. 9 refs., 4 figs., 1 tab.
Three phase full wave dc motor decoder
Studer, P. A. (Inventor)
1977-01-01
A three phase decoder for dc motors is disclosed which employs an extremely simple six transistor circuit to derive six properly phased output signals for fullwave operation of dc motors. Six decoding transistors are coupled at their base-emitter junctions across a resistor network arranged in a delta configuration. Each point of the delta configuration is coupled to one of three position sensors which sense the rotational position of the motor. A second embodiment of the invention is disclosed in which photo-optical isolators are used in place of the decoding transistors.
Fast wave current drive experiment on the DIII-D tokamak
International Nuclear Information System (INIS)
Petty, C.C.; Pinsker, R.I.; Chiu, S.C.; deGrassie, J.S.; Harvey, R.W.; Lohr, J.; Luce, T.C.; Mayberry, M.J.; Prater, R.; Porkolab, M.; Baity, F.W.; Goulding, R.H.; Hoffman, J.D.; James, R.A.; Kawashima, H.
1992-06-01
One method of radio-frequency heating which shows theoretical promise for both heating and current drive in tokamak plasmas is the direct absorption by electrons of the fast Alfven wave (FW). Electrons can directly absorb fast waves via electron Landau damping and transit-time magnetic pumping when the resonance condition ω - κ parallele υ parallele = O is satisfied. Since the FW accelerates electrons traveling the same toroidal direction as the wave, plasma current can be generated non-inductively by launching FW which propagate in one toroidal direction. Fast wave current drive (FWCD) is considered an attractive means of sustaining the plasma current in reactor-grade tokamaks due to teh potentially high current drive efficiency achievable and excellent penetration of the wave power to the high temperature plasma core. Ongoing experiments on the DIII-D tokamak are aimed at a demonstration of FWCD in the ion cyclotron range of frequencies (ICRF). Using frequencies in the ICRF avoids the possibility of mode conversion between the fast and slow wave branches which characterized early tokamak FWCD experiments in the lower hybrid range of frequencies. Previously on DIII-D, efficient direct electron heating by FW was found using symmetric (non-current drive) antenna phasing. However, high FWCD efficiencies are not expected due to the relatively low electron temperatures (compared to a reactor) in DIII-D
Development of supersonic plasma flows by use of a magnetic nozzle and an ICRF heating
Energy Technology Data Exchange (ETDEWEB)
Inutake, M.; Ando, A.; Hattori, K.; Tobari, H.; Hosokawa, Y.; Sato, R.; Hatanaka, M.; Harata, K. [Tohoku Univ., Dept. of Electrical Engineering, Sendai (Japan)
2004-07-01
A high-beta, supersonic plasma flow plays a crucial role in MHD phenomena in space and fusion plasmas. There are a few experimental researches on production and control of a fast flowing plasma in spite of a growing significance in the magnetized-plasma flow dynamics. A magneto-plasma-dynamic arc-jet (MPDA) is one of promising devices to produce a supersonic plasma flow and has been utilized as an electric propulsion device with a higher specific impulse and a relatively larger thrust. We have improved the performance of an MPDA to produce a quasi-steady plasma flow with a transonic and supersonic Mach number in a highly-ionized state. There are two methods in order to control an ion-acoustic Mach number of the plasma flow exhausted from an MPDA: one is to use a magnetic Laval nozzle to convert a thermal energy to a flow energy and the other is a combined system of an ion heating and a divergent magnetic nozzle. The former is an analogous method to a compressible air flow and the latter is the method proposed in an advanced thruster for a manned interplanetary space mission. We have clarified the plasma flow characteristics in various shapes of a magnetic field configuration. It was demonstrated that the Mach number of the plasma flow could increase up to almost 3 in a divergent magnetic nozzle field. This paper reports recent results on the flow field improvements: one is on a magnetic-Laval-nozzle effects observed at the muzzle region of the MPDA, and the other is on ICRF (ion-cyclotron-range of frequency) heating of a supersonic plasma by use of a helical antenna. (authors)
Plasma enhanced RF power deposition on ICRF antennas in Tore Supra
International Nuclear Information System (INIS)
Goulding, R.H.; Harris, J.H.; Carter, M.D.; Hoffman, D.J.; Hogan, J.T.; Ryan, P.M.; Beaumont, B.; Bremond, S.; Hutter, T.
1997-01-01
The dual-strap Tore Supra ICRF antennas have been very successful in coupling high power fluxes > 16 MW/m2 to the plasma. In many cases it has been found that the power is limited not by the voltages and currents that can be sustained on antenna components, but rather by localized increases in antenna surface temperatures which are correlated with increased impurity levels. Hot spots have been observed using an IR imaging system with peak temperatures as high as 1,100 C after 2 s, and as little as 1.5 MW power coupled from a single launcher. The maximum temperature observed is highly dependent on antenna phasing, and is lowest with dipole (π) phasing of the relative antenna currents. Both toroidal and poloidal asymmetries in hot spot distribution have been observed, and interestingly, the toroidal asymmetry has been found to vary when the phase is changed from +π/2 to -π/2. Significant differences in the temperature profiles have been seen on the two types of Faraday shield in use, which appears to be related to the fact that one type has a recessed center septum between straps while the other does not. In some cases, the peak temperature has been observed to increase as the antenna/plasma gap is increased, while the peak remains in the same location. This behavior suggests that voltages generated by currents flowing in the Faraday shield structure itself may play a role in generating potentials responsible for the hot spots, in addition to rf fields in the plasma. In this paper data on antenna surface heating and loading data as a function of plasma density, antenna/plasma gap, and phasing will be presented. Calculations from the RANT3D electromagnetic code together with bench measurements of electric fields near the antenna surface will also be shown
Hellesen, C.; Mantsinen, M.; Conroy, S.; Ericsson, G.; Eriksson, J.; Kiptily, V. G.; Nabais, F.; Contributors, JET
2018-05-01
ICRF heating at the fundamental cyclotron frequency of a hydrogen minority ion species also gives rise to a partial power absorption by deuterium ions at their second harmonic resonance. This paper studies the deuterium distributions resulting from such 2nd harmonic heating at JET using neutron emission spectroscopy data from the time of flight spectrometer TOFOR. The fast deuterium distributions are obtained over the energy range 100 keV to 2 MeV. Specifically, we study how the fast deuterium distributions vary as ICRF heating is used alone as well as in combination with NBI heating. When comparing the different heating scenarios, we observed both a difference in the shapes of the distributions as well as in their absolute level. The differences are most pronounced below 0.5 MeV. Comparisons are made with corresponding distributions calculated with the code PION. We find a good agreement between the measured distributions and those calculated with PION, both in terms of their shapes as well as their amplitudes. However, we also identified a period with signs of an inverted fast ion distribution, which showed large disagreements between the modeled and measured results. Resonant interactions with tornado modes, i.e. core localized toroidal alfven eigenmodes (TAEs), are put forward as a possible explanation for the inverted distribution.
ICRF experiments and synergy with LHCD on HT-6M tokamak
International Nuclear Information System (INIS)
Li, J.; Yin, F.X.; Wan, B.N.
1997-01-01
The successful ion cyclotron heating (ICRH) experiment with high power density of nearly 1MW/m 3 was carried out in HT-6M tokamak. The good heating efficiency was achieved by using different wall conditioning techniques, such as He GDC, Ti gettering and boronization. With 300kW injected RF power, the ion temperature reach about 750eV and Te increases from 700eV to about 1keV. Synergy effects between lower hybrid current drive (LHCD) and ICRH have some unique features. The current driven efficiency improved in full current drive case from 0.8x10 19 AW -1 M -2 (without ICRH) to 1.75x10 19 AW -1 M -2 (with ICRH). The reason for this high current driven efficiency may because the mode conversion at ion-ion hybrid resonance to an Ion Bernstein Wave (IBW) which is damped on the fast electron. (author)
International Nuclear Information System (INIS)
Dumont, R.J.; Phillips, C.K.; Smithe, D.N.
2003-01-01
Auxiliary heating supplied by externally launched electromagnetic waves is commonly used in toroidal magnetically confined fusion experiments for profile control via localized heating, current drive and perhaps flow shear. In these experiments, the confined plasma is often characterized by the presence of a significant population of non-thermal species arising from neutral beam injection, from acceleration of the particles by the applied waves, or from copious fusion reactions in future devices. Such non-thermal species may alter the wave propagation as well as the wave absorption dynamics in the plasma. Previous studies have treated the corresponding velocity distributions as either equivalent Maxwellians, or else have included realistic distributions only in the finite Larmor radius limit. In this work, the hot plasma dielectric response of the plasma has been generalized to treat arbitrary distribution functions in the non-relativistic limit. The generalized dielectric tensor has been incorporated into a one-dimensional full wave all-orders kinetic field code. Initial comparative studies of ion cyclotron range of frequency wave propagation and heating in plasmas with nonthermal species, represented by realistic distribution functions or by appropriately defined equivalent Maxwellians, have been completed for some specific experiments and are presented
Validation of a 3D/1D Simulation Tool for ICRF Antennas
International Nuclear Information System (INIS)
Maggiora, R.; Lancellotti, V.; Milanesio, D.; Vecchi, G.; Kyrytsya, V.; Parisot, A.; Wukitch, S. J.
2005-01-01
TOPICA is an innovative tool for the simulation of the Ion Cyclotron Radio Frequency (ICRF) antenna systems that incorporates commercial-grade graphic interfaces into a fully 3D self-consistent description of the antenna geometry and an accurate description of the plasma; it can be considered as a 'Virtual Prototyping Laboratory' to assist the detailed design phase of the antenna system. Recent theoretical and computational advances of the TOPICA code has allowed to incorporate a CAD drawing capability of the antenna geometry, with fully 3D geometrical modeling, and to combine it with a 1D accurate plasma description that takes into account density and temperature profiles, and FLR effects; the profiles are inserted directly from measured data (when available), or specified analytically by the user. The coaxial feeding line is modeled as such; computation and visualization of relevant parameters (input scattering parameters, current and field distributions, etc.) complete the suite. The approach to the problem is based on an integral-equation formulation for the self-consistent evaluation of the current distribution on the conductors. The environment has been subdivided in two coupled region: the plasma region and the vacuum region. The two problems are linked self-consistently by representing the field continuity in terms of equivalent (unknown) sources. In the vacuum region all the calculations are executed in the spatial (configuration) domain, and this allows triangular-facet description of the arbitrarily shaped conductors and associated currents; in the plasma region a spectral representation of the fields is used, which allows to enter the plasma effect via a surface impedance matrix; for this reason any plasma model can be used, and at present the FELICE code has been adopted; special techniques have been adopted to increase the numerical efficiency. The TOPICA suite has been previously tested against assessed codes and against measurements of mock-ups and
International Nuclear Information System (INIS)
Beklaryan, Leva A
2011-01-01
A finite difference analogue of the wave equation with potential perturbation is investigated, which simulates the behaviour of an infinite rod under the action of an external longitudinal force field. For a homogeneous rod, describing solutions of travelling wave type is equivalent to describing the full space of classical solutions to an induced one-parameter family of functional differential equations of point type, with the characteristic of the travelling wave as parameter. For an inhomogeneous rod, the space of solutions of travelling wave type is trivial, and their 'proper' extension is defined as solutions of 'quasitravelling' wave type. By contrast to the case of a homogeneous rod, describing the solutions of quasitravelling wave type is equivalent to describing the quotient of the full space of impulsive solutions to an induced one-parameter family of point-type functional differential equations by an equivalence relation connected with the definition of solutions of quasitravelling wave type. Stability of stationary solutions is analyzed. Bibliography: 9 titles.
RF wave simulation for cold edge plasmas using the MFEM library
Shiraiwa, S.; Wright, J. C.; Bonoli, P. T.; Kolev, T.; Stowell, M.
2017-10-01
A newly developed generic electro-magnetic (EM) simulation tool for modeling RF wave propagation in SOL plasmas is presented. The primary motivation of this development is to extend the domain partitioning approach for incorporating arbitrarily shaped SOL plasmas and antenna to the TORIC core ICRF solver, which was previously demonstrated in the 2D geometry [S. Shiraiwa, et. al., "HISTORIC: extending core ICRF wave simulation to include realistic SOL plasmas", Nucl. Fusion in press], to larger and more complicated simulations by including a 3D realistic antenna and integrating RF rectified sheath potential model. Such an extension requires a scalable high fidelity 3D edge plasma wave simulation. We used the MFEM [http://mfem.org], open source scalable C++ finite element method library, and developed a Python wrapper for MFEM (PyMFEM), and then a radio frequency (RF) wave physics module in Python. This approach allows for building a physics layer rapidly, while separating the physics implementation being apart from the numerical FEM implementation. An interactive modeling interface was built on pScope [S Shiraiwa, et. al. Fusion Eng. Des. 112, 835] to work with an RF simulation model in a complicated geometry.
International Nuclear Information System (INIS)
Bhatnagar, V.P.; Taroni, A.; Ellis, J.J.; Jacquinot, J.; Start, D.F.H.
1989-01-01
The ion cyclotron resonance heating of monster sawtooth (period greater than the energy confinement time) and pellet-fueled peaked-density profiles in limiter discharges of JET Tokamak are studied. The monster sawtooth is a characteristic JET regime which is related to fast ions generated during the minority ion heating. In the ICRF heating of peaked-density profile discharges, we find typically the T i0 is higher roughly by a factor of 2 and T e0 roughly by 35% at a fixed P TOT /n e0 when compared to non-peaked profile cases. Here, T e0 and T i0 are central electron and ion temperatures, respectively, n e0 is the central electron density and P TOT is the total input power. The ion heating is improved in the pellet case, in part, due to a higher collisionality between the background ions and the energetic minority, but more significantly by a reduction of local ion energy transport in the central region. The transport-code simulation of these discharges reveals that there is a reduction of both χ e and χ i in the central region of the plasma in the ICRF heated peaked-profile discharges where χ e and χ i are the electron and ion heat conductivities, respectively. The improvement of confinement is not explained quantitatively by any of the existing η i -driven turbulence theories as the n i parameter (η i = d ln T i /d ln n i where T i is the ion temperature and n i is the ion density), instead of dropping below the critical value, remains above it for most of the duration of the improved confinement phase. The physical mechanism(s) that plays a role in this improvement is not yet clear. (author)
Pietrzak, Robert H.; Goldstein, Risë B.; Southwick, Steven M.; Grant, Bridget F.
2010-01-01
The present study used data from the Wave 2 National Epidemiologic Survey on Alcohol and Related Conditions (n=34,653) to examine lifetime Axis I psychiatric comorbidity of posttraumatic stress disorder (PTSD) in a nationally representative sample of U.S. adults. Lifetime prevalences±standard errors of PTSD and partial PTSD were 6.4%±0.18 and 6.6%±0.18, respectively. Rates of PTSD and partial PTSD were higher among women (8.6%±0.26 and 8.6%±0.26) than men (4.1%±0.19 and 4.5%±0.21). Respondents with both PTSD and partial PTSD most commonly reported unexpected death of someone close, serious illness or injury to someone close, and sexual assault as their worst stressful experiences. PTSD and partial PTSD were associated with elevated lifetime rates of mood, anxiety, and substance use disorders, and suicide attempts. Respondents with partial PTSD generally had intermediate odds of comorbid Axis I disorders and psychosocial impairment relative to trauma controls and full PTSD. PMID:21168991
Pietrzak, Robert H.; Goldstein, Risë B.; Southwick, Steven M.; Grant, Bridget F.
2011-01-01
Objectives To present findings on the prevalence, correlates, and psychiatric comorbidity of DSM-IV posttraumatic stress disorder (PTSD) and partial PTSD in a nationally representative sample of U.S. older adults. Design, Setting, and Participants Face-to-face interviews with 9,463 adults aged 60 years and older in the Wave 2 National Epidemiologic Survey on Alcohol and Related Conditions. Measurements Sociodemographic correlates, worst stressful experiences, comorbid lifetime mood, anxiety, substance use, and personality disorders, psychosocial functioning, and suicide attempts. Results Lifetime prevalences±standard errors of PTSD and partial PTSD were 4.5%±0.25 and 5.5%±0.27, respectively. Rates were higher in women (5.7%±0.37 and 6.5%±0.39) than men (3.1%±0.31 and 4.3%±0.37). Older adults with PTSD most frequently identified unexpected death of someone close, serious illness or injury to someone close, and own serious or life-threatening illness as their worst stressful events. Older adults exposed to trauma but without full or partial PTSD and respondents with partial PTSD most often identified unexpected death of someone close, serious illness or injury to someone close, and indirect experience of 9/11 as their worst events. PTSD was associated with elevated odds of lifetime mood, anxiety, drug use, and borderline and narcissistic personality disorders, and decreased psychosocial functioning. Partial PTSD was associated with elevated odds of mood, anxiety, and narcissistic and schizotypal personality disorders, and poorer psychosocial functioning relative to older adults exposed to trauma but without full or partial PTSD. Conclusions PTSD among older adults in the United States is slightly more prevalent than previously reported and associated with considerable psychiatric comorbidity and psychosocial dysfunction. Partial PTSD is associated with significant psychiatric comorbidity, particularly with mood and other anxiety disorders. PMID:22522959
Pietrzak, Robert H.; Goldstein, Risë B.; Southwick, Steven M.; Grant, Bridget F.
2010-01-01
Background While it is well known that personality disorders are associated with trauma exposure and PTSD, limited nationally representative data are available on DSM-IV personality disorders that co-occur with posttraumatic stress disorder (PTSD) and partial PTSD. Methods Face-to-face interviews were conducted with 34,653 adults participating in the Wave 2 National Epidemiologic Survey on Alcohol and Related Conditions. Logistic regression analyses controlling for sociodemographics and additional psychiatric comorbidity evaluated associations of PTSD and partial PTSD with personality disorders. Results Prevalence rates of lifetime PTSD and partial PTSD were 6.4% and 6.6%, respectively. After adjustment for sociodemographic characteristics and additional psychiatric comorbidity, respondents with full PTSD were more likely than trauma controls to meet criteria for schizotypal, narcissistic, and borderline personality disorders (ORs=2.1–2.5); and respondents with partial PTSD were more likely than trauma controls to meet diagnostic criteria for borderline (OR=2.0), schizotypal (OR=1.8), and narcissistic (OR=1.6) PDs. Women with PTSD were more likely than controls to have obsessive-compulsive PD. Women with partial PTSD were more likely than controls to have antisocial PD; and men with partial PTSD were less likely than women with partial PTSD to have avoidant PD. Conclusions PTSD and partial PTSD are associated with borderline, schizotypal, and narcissistic personality disorders. Modestly higher rates of obsessive-compulsive PD were observed among women with full PTSD, and of antisocial PD among women with partial PTSD. PMID:20950823
Investigation of electrostatic waves in the ion cyclotron range of frequencies in L-4 and ACT-1
International Nuclear Information System (INIS)
Ono, Masayuki.
1993-05-01
Electrostatic waves in the ion cyclotron range of frequencies (ICRF) were studied in the Princeton L-4 and ACT-1 devices for approximately ten years, from 1975 to 1985. The investigation began in the L-4 linear device, looking for the parametric excitation of electrostatic ion cyclotron waves in multi-ion-species plasmas. In addition, this investigation verified multi-ion-species effects on the electrostatic ion cyclotron wave dispersion religion including the ion-ion hybrid resonance. Finite-Larmor-radius modification of the wave dispersion relation was also observed, even for ion temperatures of T i ∼ 1/40 eV. Taking advantage of the relatively high field and long device length of L-4, the existence of the cold electrostatic ion cyclotron wave (CES ICW) was verified. With the arrival of the ACT-1 toroidal device, finite-Larmor-radius (FLR) waves were studied in a relatively collisionless warm-ion hydrogen plasma. Detailed investigations of ion Bernstein waves (IBW) included the verification of mode-transformation in their launching, their wave propagation characteristics, their absorption, and the resulting ion heating. This basic physics activity played a crucial role in developing a new reactor heating concept termed ion Bernstein wave heating. Experimental research in the lower hybrid frequency range confirmed the existence of FLR effects near the lower hybrid resonance, predicted by Stix in 1965. In a neon plasma with a carefully placed phased wave exciter, the neutralized ion Bernstein wave was observed for the first time. Using a fastwave ICRF antenna, two parasitic excitation processes for IBW -- parametric instability and density-gradient-driven excitation -- were also discovered. In the concluding section of this paper, a possible application of externally launched electrostatic waves is suggested for helium ash removal from fusion reactor plasmas
Parametric analysis of change in wave number of surface waves
Directory of Open Access Journals (Sweden)
Tadić Ljiljana
2015-01-01
Full Text Available The paper analyzes the dependence of the change wave number of materials soil constants, ie the frequency of the waves. The starting point in this analysis cosists of wave equation and dynamic stiffness matrix of soil.
Developed Turbulence: From Full Simulations to Full Mode Reductions
Grossmann, Siegfried; Lohse, Detlef; Reeh, Achim
1996-01-01
Developed Navier-Stokes turbulence is simulated with varying wave-vector mode reductions. The flatness and the skewness of the velocity derivative depend on the degree of mode reduction. They show a crossover towards the value of the full numerical simulation when the viscous subrange starts to be
DEFF Research Database (Denmark)
Kofoed, Jens Peter; Frigaard, Peter
Wave Dragon is a wave energy converter of the overtopping type. The device has been thoroughly tested on a 1:51.8 scale model in wave laboratories and a 1:4.5 scale model deployed in Nissum Bredning, a large inland waterway in Denmark. Based on the experience gained a full scale, multi MW prototype...
International Nuclear Information System (INIS)
Lehrman, I.S.; Colestock, P.L.; McNeill, D.H.; Greene, G.J.; Bernabei, S.; Hosea, J.C.; Ono, M.; Shohet, J.L.; Wilson, J.R.
1989-04-01
Edge measurements have been conducted on the PLT tokamak under a variety of operating conditions in order to ascertain the relevant processes at work in coupling rf power to plasmas. The edge density is found to increase significantly with the application of ICRF, and electron heating occurs in the vicinity of the Faraday shield surrounding the antenna. Spectroscopic measurements indicate that the energized antenna is a significant particle source. The relative increase of metallic impurities was found to be /approximately/2.7 times larger than the corresponding increase in deuterium. In addition, the relative increase of deuterium and impurities was /approximately/3--4 times greater at the energized antenna than at other locations around the torus. Model calculations show that for deuterium released from the Faraday shield, the D/sub α/ emission is localized radially to a region within 4 cm of the antenna. A correlation was found between the edge density and the D/sub α/ intensity that justifies its use as a measure of the particle source rate. 26 refs., 14 figs
International Nuclear Information System (INIS)
Messiaen, A.; Vervier, M.; Dumortier, P.; Grine, D.; Lamalle, P.U.; Durodie, F.; Koch, R.; Louche, F.; Weynants, R.
2009-01-01
The reference design for the ICRF antenna of ITER is constituted by a tight array of 24 straps grouped in eight triplets. The matching network must be load resilient for operation in ELMy discharges and must have antenna spectrum control for heating or current drive operation. The load resilience is based on the use of either hybrid couplers or conjugate-T circuits. However, the mutual coupling between the triplets at the low expected loading strongly counteracts the load resilience and the spectrum control. Using a mock-up of the ITER antenna array with adjustable water load matching solutions are designed. These solutions are derived from transmission line modelling based on the measured scattering matrix and are finally tested. We show that the array current spectrum can be controlled by the anti-node voltage distribution and that suitable decoupler circuits can not only neutralize the adverse mutual coupling effects but also monitor this anti-node voltage distribution. A matching solution using four 3 dB hybrids and the antenna current spectrum feedback control by the decouplers provides outstanding performance if each pair of poloidal triplets undergoes a same load variation. Finally, it is verified by modelling that this matching scenario has the same antenna spectrum and load resilience performances as the antenna array loaded by plasma as described by the TOPICA simulation. This is true for any phasing and frequency in the ITER frequency band. The conjugate-T solution is presently considered as a back-up option.
Gyrokinetic approach to the propagation of electromagnetic waves in nonuniform bounded plasma slabs
International Nuclear Information System (INIS)
Sauter, O.; Vaclavik, J.
1994-05-01
A new code, SEMAL, has been developed which solves the linearized Vlasov-Maxwell wave equations to all orders in Larmor radii. Arbitrary density and temperature profiles as well as nonuniform magnetic fields are considered in slab geometry. The vacuum regions adjacent to the plasma slab are limited by perfect conducting walls and contain an antenna as an excitation source. The linear response is obtained by solving the system of one first-order and two second-order integro-differential equations using a non-polluting finite element discretization. The general equations in the Fourier space, derived in a new comprehensive way, and their inverse transform, using k y =0, are described as well as the convergence and non-polluting properties of the method. We present the results concerning the influence of alpha particles on ICRF heating schemes for ITER, where we show that small alphas concentration can alter the steady-state operation envisaged with ICRF fast wave current-drive. (author) 7 figs., 3 tabs., 28 refs
International Nuclear Information System (INIS)
Takase, Y.; Fiore, C.L.; McDermott, F.S.; Moody, J.D.; Porkolab, M.; Shepard, T.; Squire, J.
1987-01-01
Mode-converted and directly excited ion Bernstein waves (IBW) were studied using CO 2 laser scattering in the Alcator C tokamak. During the ICRF fast wave heating experiments, mode-converted IBW was observed on the high-field side of the resonance in both second harmonic and minority heating regimes. By comparing the relative scattered powers from the two antennas separated by 180 0 toroidally, an increased toroidal wave damping with increasing density was inferred. In the IBW heating experiments, optimum direct excitation is obtained when an ion-cyclotron harmonic layer is located just behind the antenna. Wave absorption at the ω = 3Ω/sub D/ = 1.5Ω/sub H/ layer was directly observed. Edge ion heating was inferred from the IBW dispersion when this absorption layer was located in the plasma periphery, which may be responsible for the observed improvement in particle confinement
Ion Bernstein wave heating experiments in HT-7 superconducting tokamak
International Nuclear Information System (INIS)
Zhao Yanping
2005-01-01
Ion Bernstein Wave (IBW) experiments have been carried out in recent years in the HT-7 superconducting Tokamak. The electron heating experiment has been concentrated on deuterium plasma with an injecting RF power up to 350 kw. The globe heating and localized heating can be seen clearly by controlling the ICRF resonance layer's position. On-axis and off-axis electron heating have been realized by properly setting the target plasma parameters. Experimental results show that the maximum increment in electron temperature has been more than 1 keV, the electron temperature profile has been modified by IBW under different plasma conditions, and both energy and particle confinement improvements have been obtained. (author)
Ion Bernstein wave heating on the Compact Ignition Tokamak (CIT)
International Nuclear Information System (INIS)
Ignat, D.W.; Ono, M.
1989-02-01
In the present plan, CIT is to be heated by power in the ion cyclotron range of frequencies (ICRF), and electron cyclotron heating (ECH) may be used if suitable rf sources can be developed. We consider the option of ion Bernstein wave heating (IBWH). The key points are that a simple vacuum waveguide launcher can be well- removed from high fluxes of heat and particles and that the development of a suitable source is straightforward. A practical point is that an IBWH waveguide launcher, including transition from coaxial power feeds, fits inside the shield wall surrounding CIT. To confirm IBWH as an option for CIT, experiments are needed on a shaped, H-mode plasma at high power. Successful experiments should be followed by a tube development program to allow CIT heating at 200 - 275 MHz. 2 refs., 3 figs
Phased antenna arrays for fast wave power generation
International Nuclear Information System (INIS)
Bosia, G.; Jacquinot, J.
1991-01-01
A method for the generation of travelling waves in the Ion Cyclotron frequency range in JET is presented. The success of the method relies on the control of the array toroidal current, which in turn, is obtained by a coordinated vectorial control of the array power sources and tuning networks. This method has general application to present and future ICRF arrays. For uninterrupted, periodically fed and resonant toroidal arrays, phased operation requires only conventional tuning devices. For localised arrays, phased operation is inefficient at low plasma coupling. This inefficiency can be however removed with the addition of external coupling structures either at the antenna or at the generator ends. The performances of JET A1 antennae in phased operation is presented. The design philosophy for the JET A2 phased arrays is also discussed. These methods are applicable and extensible to Next Step Devices design
Recent Developments in High-Harmonic Fast Wave Physics in NSTX
International Nuclear Information System (INIS)
LeBlanc, B.P.; Bell, R.E.; Bonoli, P.; Harvey, R.; Heidbrink, W.W.; Hosea, J.C.; Kaye, S.M.; Liu, D.; Maingi, R.; Medley, S.S.; Ono, M.; Podesta, M.; Phillips, C.K.; Ryan, P.M.; Roquemore, A.L.; Taylor, G.; Wilson, J.R.
2010-01-01
Understanding the interaction between ion cyclotron range of frequency (ICRF) fast waves and the fast-ions created by neutral beam injection (NBI) is critical for future devices such as ITER, which rely on a combination ICRF and NBI. Experiments in NSTX which use 30 MHz High-Harmonic Fast-Wave (HHFW) ICRF and NBI heating show a competition between electron heating via Landau damping and transit-time magnetic pumping, and radio-frequency wave acceleration of NBI generated fast ions. Understanding and mitigating some of the power loss mechanisms outside the last closed flux surface (LCFS) has resulted in improved HHFW heating inside the LCFS. Nevertheless a significant fraction of the HHFW power is diverted away from the enclosed plasma. Part of this power is observed locally on the divertor. Experimental observations point toward the radio-frequency (RF) excitation of surface waves, which disperse wave power outside the LCFS, as a leading loss mechanism. Lithium coatings lower the density at the antenna, thereby moving the critical density for perpendicular fast-wave propagation away from the antenna and surrounding material surfaces. Visible and infrared imaging reveal flows of RF power along open field lines into the divertor region. In L-mode -- low average NBI power -- conditions, the fast-ion D-alpha (FIDA) diagnostic measures a near doubling and broadening of the density profile of the upper energetic level of the fast ions concurrent with the presence of HHFW power launched with k// = -8m-1. We are able to heat NBI-induced H-mode plasmas with HHFW. The captured power is expected to be split between absorption by the electrons and absorption by the fast ions, based on TORIC calculation. In the case discussed here the Te increases over the whole profile when ∼2MW of HHFW power with antenna k// = 13m-1 is applied after the H-mode transition. But somewhat unexpectedly fast-ion diagnostics do not observe a change between the HHFW heated NBI discharge and the
Introduction to wave heating and current drive in magnetized plasmas
International Nuclear Information System (INIS)
Pinsker, R. I.
2001-01-01
The development of high-power wave heating and current drive in magnetized plasmas in the last 40 years is a major ongoing success story in plasma science. A hallmark of this area of research has been the detailed quantitative comparison of theory and experiment; the good agreement consistently found is indicative of the robustness and the predictive power of the underlying theory. This tutorial paper is a brief overview of the fundamental concepts and applications of this branch of plasma science. Most of the high-power applications have been in three frequency regimes: the ion cyclotron range of frequencies (ICRF), the lower hybrid range of frequencies (LHRF), and the electron cyclotron range of frequencies (ECRF). The basic physics of wave propagation and damping in these regimes is briefly discussed. Some of the coupling structures (antennas) used to excite the waves at the plasma boundary are described, and the high-power systems used to generate the wave energy are touched on. Representative examples of the remarkably wide range of applications of high-power wave heating and current drive in high-temperature fusion plasmas will be discussed
Coronal Waves and Oscillations
Directory of Open Access Journals (Sweden)
Nakariakov Valery M.
2005-07-01
Full Text Available Wave and oscillatory activity of the solar corona is confidently observed with modern imaging and spectral instruments in the visible light, EUV, X-ray and radio bands, and interpreted in terms of magnetohydrodynamic (MHD wave theory. The review reflects the current trends in the observational study of coronal waves and oscillations (standing kink, sausage and longitudinal modes, propagating slow waves and fast wave trains, the search for torsional waves, theoretical modelling of interaction of MHD waves with plasma structures, and implementation of the theoretical results for the mode identification. Also the use of MHD waves for remote diagnostics of coronal plasma - MHD coronal seismology - is discussed and the applicability of this method for the estimation of coronal magnetic field, transport coefficients, fine structuring and heating function is demonstrated.
Revivals of Rydberg wave packets
International Nuclear Information System (INIS)
Bluhm, R.; Kostelecky, V.A.; Tudose, B.
1998-01-01
We examine the revival structure of Rydberg wave packets. These wave packets exhibit initial classical periodic motion followed by a sequence of collapse, fractional (or full) revivals, and fractional (or full) superrevivals. The effects of quantum defects on wave packets in alkali-metal atoms and a squeezed-state description of the initial wave packets are also considered. We then examine the revival structure of Rydberg wave packets in the presence of an external electric field - that is, the revival structure of Stark wave packets. These wave packets have energies that depend on two quantum numbers and exhibit new types of interference behavior
International Nuclear Information System (INIS)
Kumazawa, R.; Mutoh, T.; Saito, K.
2008-10-01
A long pulse plasma discharge experiment was carried out using RF heating power in the Large Helical Device (LHD), a currentless magnetic confining system. Progress in long pulse operation is summarized since the 10th experimental campaign (2006). A scaling relation of the plasma duration time to the applied RF power has been derived from the experimental data so far collected. It indicates that there exists a critical divertor temperature and consequently a critical RF heating power P RFcrit =0.65 MW. The area on the graph of the duration time versus the RF heating power was extended over the scaling relation by replacing divertor plates with new ones with better heat conductivity. The cause of the plasma collapse at the end of the long pulse operation was found to be the penetration of metal impurities. Many thin flakes consisting of heavy metals and graphite in stratified layers were found on the divertor plates and it was thought that they were the cause of impurity metals penetrating into the plasma. In a simulation involving injecting a graphite-coated Fe pellet to the plasma it was found that 230 Eμm in the diameter of the Fe pellet sphere was the critical size which led the plasma to collapse. A mode-conversion heating method was examined in place of the minority ICRF heating which has been employed in almost all the long-pulse plasma discharges. It was found that this method was much better from the viewpoint of achieving uniformity of the plasma heat load to the divertors. It is expected that P RFcrit will be increased by using the mode-conversion heating method. (author)
Edge localized modes and edge pedestal in NBI and ICRF heated H, D and T-plasmas in JET
International Nuclear Information System (INIS)
Bhatnagar, V.; Lingertat, J.; Barnsley, R.
1998-12-01
Based on experiments carried out in JET in D:T mixtures varying from 100:0 to 5:95 and those carried out in hydrogen plasmas, the isotopic mass dependence of ELM parameters and the edge pedestal pressure in neutral beam (NBI) and ion cyclotron resonance (ICRF) heated H-mode plasmas is presented. The ELM frequency is found to decrease with the atomic mass number both in ICRH and NBI discharges. However, the frequency in the case of ICRH is about 8 - 10 times higher than in the NBI case. Assuming that ELMs occur at a critical edge pressure gradient, limited by the ballooning instability, the scaling of the maximum edge pressure is most consistent with the assumption that the width of the transport barrier scales as the ion poloidal Larmor radius governed by the average energy of fast ions at the edge. The critical edge pressure in NBI heated discharges increases with the isotopic mass which. is consistent with the higher deduced width of the edge transport, barrier in tritium than in deuterium and hydrogen. The critical edge pressure in ICRH discharges is smaller, presumably, due to the smaller fast-ion contribution to the edge region. As a consequence of the edge pressure scaling with isotopic mass, the edge operational space in the n e - T e diagram increases with operation in tritium. If the evidence that the edge pedestal width is governed by the average energy of fast ions in the edge prevails, the pedestal in ITER would be controlled by the slowing down energy spectrum of α-particles in the edge. (author)
ICRF antenna modifications and additions for TFTR: Relevance to BPX/ITER projections
International Nuclear Information System (INIS)
Hosea, J.; Phillips, C.K.; Raftopoulos, S.; Stevens, J.; Wilson, J.R.
1991-01-01
The TFTR Bay L and M antennas have been modified to improve their power handling capability. In particular, the Bay L antenna, which exhibited a lower than expected loading resistance, now has a configuration similar to that of Bay M -- slotted walls and septum -- and together with Bay M is expected to support 7 MW operations. The in situ loading enhancement achieved for the Modified Bay L design will serve to quantify models for the coupling effects of slots. Also, comparisons with Bay M loading performance will elucidate wave spectrum and antenna location (relative to in-vessel structures) effects. Two new antennas, with single/double row shields slanted at 6 degree (along B) are to be added in the near future to augment the power capability to ∼12.5 MW. The relevance of the four antenna array features to quantifying BPX/ITER antenna characteristic projections for heating and current drive is discussed. 8 refs., 5 figs
Numerical investigation of ICRF antenna designs and heating schemes for Alcator C
International Nuclear Information System (INIS)
Blackfield, D.T.; Blackwell, B.D.
1983-02-01
Initially, approximately 500 kW of rf power will be launched through one port of Alcator C at a frequency of 180 to 220 MHz. We use a hot-plasma slab model to examine antenna coupling and power deposition for second harmonic (H, B 0 = 6.7 T) heating regime. The plasma medium is assumed uniform in y and z and is stratified in x. Three-dimensional, four-mode field solutions are obtained by solution of the boundary condition equations in the x direction, and by Fourier transform methods in y and z. We study the dependence of radiation resistance upon coupling parameters such as antenna width and radial position. This is interpreted in terms of the spectral (k/sub y/, k/sub z/) distribution of power, the effect of the evanescent region at the edge, and the attenuation length of the waves
Full Plant STWAVE: SMS Graphical Interface
National Research Council Canada - National Science Library
McKee Smith, Jane; Zundel, Alan
2006-01-01
The purpose of this Coastal and Hydraulics Engineering Technical Note (CHETN) is to describe the graphical interface for the full-plane version of the wave model STWAVE (Smith et al. 2001; Smith 2001...
Determination of ICRF antenna fields in the vicinity of a 3-D Faraday shield structure
Energy Technology Data Exchange (ETDEWEB)
Ryan, P M; Rothe, K E; Whealton, J H; Shepard, T D [Oak Ridge National Lab., TN (USA)
1990-04-01
A three-dimensional (3-D) magnetostatic analysis developed at Oak Ridge National Laboratory has been used to calculate the electromagnetic transmission properties of representative Faraday shield designs. The analysis uses the long-wavelength approximation to obtain a 3-D Laplace solution for the magnetic scalar potential over one poloidal period of the Faraday shield, from which the complete magnetic field distribution may be obtained. Once the magnetic field distributions in the presence and absence of a Faraday shield are known, the flux transmission coefficient can be found, as well as any change in the distributed inductance of the current strap. The distrbuted capacitance of the strap can be found from an analogous 3-D electrostatic calculation, enabling the phase velocity of the slow-wave structure to be determined. Power dissipation in the shield may be estimated by equating the surface current on a perfect conductor with the surface magnetic field and using this surface current in conjunction with the finite conductivities of the shield materials to obtain the power distribution due to eddy current heating. (orig.).
Physics aspects and technical elements of an ICRF heating system for JET
International Nuclear Information System (INIS)
Adam, J.; Jacquinot, J.; Kuus, H.
1980-09-01
We first present an overview of the recent results obtained in existing Tokamaks. These experiments offer a critical test of the basic physics ideas, give an estimate of the overall heating performance and show the degree of development of the RF hardware. A second part is devoted to the basic water-particle physics. JET will have to work in a wide variety of plasma parameters which constitutes an unprecedented constraint. A range of frequency is found which accomodates, within limits, most of the operating scenarios foreseen in JET. Moving from the plasma to the outer world, the wave coupling theory determines the position, the surface and the voltage stand-off of the launching structure which is necessary to transmit the power. Modules capable of transmitting 5 MW per Octant are discussed in the light of the present technology. The most critical parameter influencing the antenna performance appears to be the distance from the antenna to the plasma. Finally we have summarized our experience and our discussions with the industrial firms to outline the components of the RF system: power tubes, power supply requirements, coaxial transmission lines and matching network. A lay out of the power plant is then given
Energetic particle destabilization of shear Alfven waves in stellarators and tokamaks
International Nuclear Information System (INIS)
Spong, D.A.; Carreras, B.A.; Hedrick, C.L.; Leboeuf, J.N.; Weller, A.
1994-01-01
An important issue for ignited devices is the resonant destabilization of shear Alfven waves by energetic populations. These instabilities have been observed in a variety of toroidal plasma experiments in recent years, including: beam-destabilized toroidal Alfven instabilities (TAE) in low magnetic field tokamaks, ICRF destabilized TAE's in higher field tokamaks, and global Alfven instabilities (GAE) in low shear stellarators. In addition, excitation and study of these modes is a significant goal of the TFIR-DT program and a component of the ITER physics tasks. The authors have developed a gyrofluid model which includes the wave-particle resonances necessary to excite such instabilities. The TAE linear mode structure is calculated nonperturbatively, including many of the relevant damping mechanisms, such as: continuum damping, non-ideal effects (ion FLR and electron collisionality), and ion/electron Landau damping. This model has been applied to both linear and nonlinear regimes for a range of experimental cases using measured profiles
Fast wave heating experiments in the ion cyclotron range of frequencies on ATF
Energy Technology Data Exchange (ETDEWEB)
Kwon, M; Shepard, T D; Goulding, R H [Oak Ridge National Lab., TN (United States); and others
1992-07-01
Fast wave heating experiments in the ion cyclotron range of frequencies (ICRF) were performed on target plasmas produced by 350 kW of electron cyclotron heating at 53 GHz and also by neutral beam injection in the Advanced Toroidal Facility (ATF). Various heating regimes were investigated in the frequency range between 9.2 MHz and 28.8 MHz with magnetic fields of 0.95 T and 1.9 T on axis. The nominal pulse lengths of up to 200 kW RF power were in the range between 100 and 400 ms. Data from spectroscopy, loading measurements, and edge RF and Langmuir probes were used to characterize the RF induced effects on the ATF plasma. In the hydrogen minority regime at low plasma density, large suprathermal ion tails were observed with a neutral particle analyser. At high density (n-bar{sub e} {>=} 5.0 x 10{sup 13} cm{sup -3}) substantial increases in antenna loading were observed, but ICRF power was insufficient to produce definitive heating results. A two-dimensional RF heating code, ORION, and a Fokker-Planck code, RFTRANS, were used to simulate these experiments. A simulation of future high power, higher density experiments in ATF indicates improved bulk heating results due to the improved loading and more efficient thermalization of the minority tail. (author). 29 refs, 16 figs, 3 tabs.
Auxiliary radiofrequency heating of tokamaks, Task 3
International Nuclear Information System (INIS)
Scharer, J.E.
1991-07-01
The research performed under this grant during the past three years has been concentrated on the following several key tokamak ICRF (Ion Cyclotron Range of Frequencies) coupling and heating issues: efficient coupling during the L- to H-mode transition by analysis and computer simulation of ICRF antennas edge plasma profiles; analysis of both dielectric-filled waveguide and coil ICRF antenna coupling to plasma edge profiles; benchmarking the codes to compare with current JET, D-IIID and ASDEX experimental results; ICRF full-wave field solutions, power conservation and heating analyses; and the effects of fusion alpha particle or ion tail populations on the ICRF absorption. Research progress, publications, and conference and workshop presentations are summarized in this report. 15 refs
Cycloidal Wave Energy Converter
Energy Technology Data Exchange (ETDEWEB)
Stefan G. Siegel, Ph.D.
2012-11-30
This program allowed further advancing the development of a novel type of wave energy converter, a Cycloidal Wave Energy Converter or CycWEC. A CycWEC consists of one or more hydrofoils rotating around a central shaft, and operates fully submerged beneath the water surface. It operates under feedback control sensing the incoming waves, and converts wave power to shaft power directly without any intermediate power take off system. Previous research consisting of numerical simulations and two dimensional small 1:300 scale wave flume experiments had indicated wave cancellation efficiencies beyond 95%. The present work was centered on construction and testing of a 1:10 scale model and conducting two testing campaigns in a three dimensional wave basin. These experiments allowed for the first time for direct measurement of electrical power generated as well as the interaction of the CycWEC in a three dimensional environment. The Atargis team successfully conducted two testing campaigns at the Texas A&M Offshore Technology Research Center and was able to demonstrate electricity generation. In addition, three dimensional wave diffraction results show the ability to achieve wave focusing, thus increasing the amount of wave power that can be extracted beyond what was expected from earlier two dimensional investigations. Numerical results showed wave cancellation efficiencies for irregular waves to be on par with results for regular waves over a wide range of wave lengths. Using the results from previous simulations and experiments a full scale prototype was designed and its performance in a North Atlantic wave climate of average 30kW/m of wave crest was estimated. A full scale WEC with a blade span of 150m will deliver a design power of 5MW at an estimated levelized cost of energy (LCOE) in the range of 10-17 US cents per kWh. Based on the new results achieved in the 1:10 scale experiments these estimates appear conservative and the likely performance at full scale will
CERN. Geneva
2016-01-01
In the past year, the LIGO-Virgo Collaboration announced the first secure detection of gravitational waves. This discovery heralds the beginning of gravitational wave astronomy: the use of gravitational waves as a tool for studying the dense and dynamical universe. In this talk, I will describe the full spectrum of gravitational waves, from Hubble-scale modes, through waves with periods of years, hours and milliseconds. I will describe the different techniques one uses to measure the waves in these bands, current and planned facilities for implementing these techniques, and the broad range of sources which produce the radiation. I will discuss what we might expect to learn as more events and sources are measured, and as this field matures into a standard part of the astronomical milieu.
Field and ray analyses of antenna excitations in ICRF heating of large Tokamaks
International Nuclear Information System (INIS)
Bers, A.; Lister, G.; Jacquinot, J.
1980-09-01
We present analytical and computational techniques for determining the electromagnetic fields and associated power flow excited by antenna systems external to large Tokamak plasmas. The finite poloidal and toroidal extension of the poloidal antenna current is modeled by a superposition of current sheets placed at a fixed radius outside the plasma. Antennae both with and without a screen between the current sheet and the plasma are considered. The plama is modeled by its cold dielectric tensor and inhomogeneous density and applied magnetic field. For large Tokamak plasmas in which the plasma dimensions are large compared to the antenna, the field excitation problem can be considered approximately in slab geometry. The field solution of this problem which we present, gives the electromagnetic fields excited in the edge plasma by the antennae and includes the effect of the cutoffs which may exist in this region. To proceed further into the plasma we consider a ray tracing analysis. Starting from an equiphase surface of the excited fields in the edge plasma, the group velocity rays can be followed in full toroidal geometry up to the cyclotron singular resonance region where the power is deposited in the particles. Both the amplitude and phase of the fields can be established in the vicinity of the angular surface so that the power deposition profile can be eventually calculated
Experimental study of the fast wave propagation in TFR
International Nuclear Information System (INIS)
1981-02-01
Several experiments (PLT, DIVA, ERASMUS, TFR) have shown that the heating mechanism of ICRF is dominated in Tokamaks by the presence of the ion-ion hybrid layer. The first experimental evidence of this effect came from propagation studies: a very strong damping was observed on magnetic probes since the hybrid layer was inside the plasma. Comparison with simple models which do not take into account boundary conditions have been undertaken. Recently a new theoretical model has been developped. Based on a plane, inhomogeneous, bounded plasma, it shows that the radial structure of the fast wave and hence the loading impedance of the launching coil depends on the position of the hybrid layer with respect to the plasma boundaries. This result is obtained by solving the wave equation, in the cold plasma approximation. We present here, a serie of experiments, performed in TFR. It confirms the validity of that model underlining thus the importance of radial eigenmodes, when the wave conversion layer is inside the plasma
International Nuclear Information System (INIS)
Kim, Hae Jin; Wang, Son Jong; Park, Byoung Ho; Kwak, Jong-Gu; Hillairet, Julien; Choi, Jin Joo
2015-01-01
Highlights: • Amplitude balanced 3 dB coaxial hybrid splitter has been designed and rf tested. • The proposed hybrid is applicable to ITER ICRF transmission line for load resilience. • Two-section, broadband coaxial hybrid can be tunable by changing dielectric insulator. - Abstract: RF design and network analyzer tests of broadband, amplitude-balanced coaxial hybrid junctions are presented. We have designed two 3 dB hybrid splitters with 9 and 12 in. coaxial transmission lines applicable to ITER ICRF for load-resilient operations using ANSYS HFSS. Amplitude-balanced broadband responses were obtained with the combination of impedance reductions of longitudinal and transverse branches in unequal proportion, length change of 50 Ω lines and diameter change of high impedance lines connected transversely to the T-section of the hybrid splitter, respectively. We have fabricated and RF tested the 9 in. coaxial hybrid coupler. We obtained an excellent coupling flatness of −3.2 ± 0.2 dB, phase difference of 4 degrees and return loss of 16 dB in 40–55 MHz. The measured data of 9 in. hybrid splitter is highly consistent with HFSS simulations. We found that the proposed 3 dB hybrid splitter can be tunable with amplitude-balanced, broadband response by changing dielectric insulators to keep the inner and outer conductors of coaxial line apart. The proposed 3 dB hybrid splitter can be utilized for load-resilient operations in a wide range of antenna load variations due to mode transitions or edge localized modes (ELMs) in fusion plasmas.
Energy Technology Data Exchange (ETDEWEB)
Kim, Hae Jin, E-mail: haejin@nfri.re.kr [National Fusion Research Institute, Daejeon (Korea, Republic of); Wang, Son Jong; Park, Byoung Ho; Kwak, Jong-Gu [National Fusion Research Institute, Daejeon (Korea, Republic of); Hillairet, Julien [CEA/IRFM, Saint-lez-Durance (France); Choi, Jin Joo [Kwangwoon University, Seoul (Korea, Republic of)
2015-10-15
Highlights: • Amplitude balanced 3 dB coaxial hybrid splitter has been designed and rf tested. • The proposed hybrid is applicable to ITER ICRF transmission line for load resilience. • Two-section, broadband coaxial hybrid can be tunable by changing dielectric insulator. - Abstract: RF design and network analyzer tests of broadband, amplitude-balanced coaxial hybrid junctions are presented. We have designed two 3 dB hybrid splitters with 9 and 12 in. coaxial transmission lines applicable to ITER ICRF for load-resilient operations using ANSYS HFSS. Amplitude-balanced broadband responses were obtained with the combination of impedance reductions of longitudinal and transverse branches in unequal proportion, length change of 50 Ω lines and diameter change of high impedance lines connected transversely to the T-section of the hybrid splitter, respectively. We have fabricated and RF tested the 9 in. coaxial hybrid coupler. We obtained an excellent coupling flatness of −3.2 ± 0.2 dB, phase difference of 4 degrees and return loss of 16 dB in 40–55 MHz. The measured data of 9 in. hybrid splitter is highly consistent with HFSS simulations. We found that the proposed 3 dB hybrid splitter can be tunable with amplitude-balanced, broadband response by changing dielectric insulators to keep the inner and outer conductors of coaxial line apart. The proposed 3 dB hybrid splitter can be utilized for load-resilient operations in a wide range of antenna load variations due to mode transitions or edge localized modes (ELMs) in fusion plasmas.
Swanson, DG
1989-01-01
Plasma Waves discusses the basic development and equations for the many aspects of plasma waves. The book is organized into two major parts, examining both linear and nonlinear plasma waves in the eight chapters it encompasses. After briefly discussing the properties and applications of plasma wave, the book goes on examining the wave types in a cold, magnetized plasma and the general forms of the dispersion relation that characterize the waves and label the various types of solutions. Chapters 3 and 4 analyze the acoustic phenomena through the fluid model of plasma and the kinetic effects. Th
Effects of minority ions on the propagation of the Fast Alfven wave
International Nuclear Information System (INIS)
Wong, K.L.; Kristiansen, M.; Hagler, M.
1985-01-01
Minority ions play an important role in ICRF wave heating and fast wave current drive. The former provides supplemental heating to the plasma ions, and the latter enables a Tokamak reactor to operate in steady state. The injection of minority ions greatly perturbs the propagation and absorption properties of the fast waves provided that the excitation frequency and confining magnetic field strength make the hybrid layers exist inside the plasma. A cold-plasma slab model with gradient confining magnetic field, parabolic plasma density, vacuum layer, launching antenna and conducting walls was used in studying wave propagation with and without minority ions. The wave propagation was studied individually for each discrete toroidal eigenmode (N=Rk/sub z/). There exists an asymmetric density cutoff region which is mainly due to the density variation in a single-ion plasma. The larger the torodial mode number, the larger the density cutoff region. Therefore, there exists a maximum mode number N/sub m/, which can be excited for each operating frequency. With injection of minority ions, the cutoff region for each mode number is almost unchanged. But, if one carefully chooses the excitation frequency; the hybrid layers can exist inside the plamsa for all or part of the allowed eigenmodes. Those eigenmodes with hybrid layers inside the plasma will undergo drastic change in the propagation and absorption of the waves
Turbulent wind waves on a water current
Directory of Open Access Journals (Sweden)
M. V. Zavolgensky
2008-05-01
Full Text Available An analytical model of water waves generated by the wind over the water surface is presented. A simple modeling method of wind waves is described based on waves lengths diagram, azimuthal hodograph of waves velocities and others. Properties of the generated waves are described. The wave length and wave velocity are obtained as functions on azimuth of wave propagation and growth rate. Motionless waves dynamically trapped into the general picture of three dimensional waves are described. The gravitation force does not enter the three dimensional of turbulent wind waves. That is why these waves have turbulent and not gravitational nature. The Langmuir stripes are naturally modeled and existence of the rogue waves is theoretically proved.
Heat Waves Dangers we face during periods of very high temperatures include: Heat cramps: These are muscular pains and spasms due ... that the body is having trouble with the heat. If a heat wave is predicted or happening… - ...
DEFF Research Database (Denmark)
Kramer, Morten; Brorsen, Michael; Frigaard, Peter
Denne rapport beskriver numeriske beregninger af forskellige flydergeometrier for bølgeenergianlæget Wave Star.......Denne rapport beskriver numeriske beregninger af forskellige flydergeometrier for bølgeenergianlæget Wave Star....
Energy Technology Data Exchange (ETDEWEB)
Miller, Jonah Maxwell [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
2017-10-18
This report has slides on Gravitational Waves; Pound and Rebka: A Shocking Fact; Light is a Ruler; Gravity is the Curvature of Spacetime; Gravitational Waves Made Simple; How a Gravitational Wave Affects Stuff Here; LIGO; This Detection: Neutron Stars; What the Gravitational Wave Looks Like; The Sound of Merging Neutron Stars; Neutron Star Mergers: More than GWs; The Radioactive Cloud; The Kilonova; and finally Summary, Multimessenger Astronomy.
Full closure strategic analysis.
2014-07-01
The full closure strategic analysis was conducted to create a decision process whereby full roadway : closures for construction and maintenance activities can be evaluated and approved or denied by CDOT : Traffic personnel. The study reviewed current...
Towne, Dudley H
1988-01-01
This excellent undergraduate-level text emphasizes optics and acoustics, covering inductive derivation of the equation for transverse waves on a string, acoustic plane waves, boundary-value problems, polarization, three-dimensional waves and more. With numerous problems (solutions for about half). ""The material is superbly chosen and brilliantly written"" - Physics Today. Problems. Appendices.
DEFF Research Database (Denmark)
This book is dedicated to various aspects of electromagnetic wave theory and its applications in science and technology. The covered topics include the fundamental physics of electromagnetic waves, theory of electromagnetic wave propagation and scattering, methods of computational analysis......, material characterization, electromagnetic properties of plasma, analysis and applications of periodic structures and waveguide components, etc....
DEFF Research Database (Denmark)
Kofoed, Jens Peter; Frigaard, Peter; Sørensen, H. C.
1998-01-01
This paper concerns with the development of the wave energy converter (WEC) Wave Dragon. This WEC is based on the overtopping principle. An overview of the performed research done concerning the Wave Dragon over the past years is given, and the results of one of the more comprehensive studies, co...
An analysis of JET fast-wave heating and current drive experiments directly related to ITER
Energy Technology Data Exchange (ETDEWEB)
Bhatnagar, V P; Eriksson, L; Gormezano, C; Jacquinot, J; Kaye, A; Start, D F.H. [Commission of the European Communities, Abingdon (United Kingdom). JET Joint Undertaking
1994-07-01
The ITER fast-wave system is required to serve a variety of purposes, in particular, plasma heating to ignition, current profile and burn control and eventually, in conjunction with other schemes, a central non-inductive current drive (CD) for the steady-state operation of ITER. The ICRF heating and current drive data that has been obtained in JET are analyzed in terms of dimensionless parameters, with a view to ascertaining its direct relevance to key ITER requirements. The analysis is then used to identify areas both in physics and technological aspects of ion-cyclotron resonance heating (ICRH) and CD that require further experimentation in ITER-relevant devices such as JET to establish the required data base. (authors). 12 refs., 8 figs.
An analysis of JET fast-wave heating and current drive experiments directly related to ITER
International Nuclear Information System (INIS)
Bhatnagar, V.P.; Eriksson, L.; Gormezano, C.; Jacquinot, J.; Kaye, A.; Start, D.F.H.
1994-01-01
The ITER fast-wave system is required to serve a variety of purposes, in particular, plasma heating to ignition, current profile and burn control and eventually, in conjunction with other schemes, a central non-inductive current drive (CD) for the steady-state operation of ITER. The ICRF heating and current drive data that has been obtained in JET are analyzed in terms of dimensionless parameters, with a view to ascertaining its direct relevance to key ITER requirements. The analysis is then used to identify areas both in physics and technological aspects of ion-cyclotron resonance heating (ICRH) and CD that require further experimentation in ITER-relevant devices such as JET to establish the required data base. (authors). 12 refs., 8 figs
Parsimonious Surface Wave Interferometry
Li, Jing
2017-10-24
To decrease the recording time of a 2D seismic survey from a few days to one hour or less, we present a parsimonious surface-wave interferometry method. Interferometry allows for the creation of a large number of virtual shot gathers from just two reciprocal shot gathers by crosscoherence of trace pairs, where the virtual surface waves can be inverted for the S-wave velocity model by wave-equation dispersion inversion (WD). Synthetic and field data tests suggest that parsimonious wave-equation dispersion inversion (PWD) gives S-velocity tomograms that are comparable to those obtained from a full survey with a shot at each receiver. The limitation of PWD is that the virtual data lose some information so that the resolution of the S-velocity tomogram can be modestly lower than that of the S-velocity tomogram inverted from a conventional survey.
Parsimonious Surface Wave Interferometry
Li, Jing; Hanafy, Sherif; Schuster, Gerard T.
2017-01-01
To decrease the recording time of a 2D seismic survey from a few days to one hour or less, we present a parsimonious surface-wave interferometry method. Interferometry allows for the creation of a large number of virtual shot gathers from just two reciprocal shot gathers by crosscoherence of trace pairs, where the virtual surface waves can be inverted for the S-wave velocity model by wave-equation dispersion inversion (WD). Synthetic and field data tests suggest that parsimonious wave-equation dispersion inversion (PWD) gives S-velocity tomograms that are comparable to those obtained from a full survey with a shot at each receiver. The limitation of PWD is that the virtual data lose some information so that the resolution of the S-velocity tomogram can be modestly lower than that of the S-velocity tomogram inverted from a conventional survey.
Directory of Open Access Journals (Sweden)
Jin Lan (兰金
2015-12-01
Full Text Available A diode, a device allowing unidirectional signal transmission, is a fundamental element of logic structures, and it lies at the heart of modern information systems. The spin wave or magnon, representing a collective quasiparticle excitation of the magnetic order in magnetic materials, is a promising candidate for an information carrier for the next-generation energy-saving technologies. Here, we propose a scalable and reprogrammable pure spin-wave logic hardware architecture using domain walls and surface anisotropy stripes as waveguides on a single magnetic wafer. We demonstrate theoretically the design principle of the simplest logic component, a spin-wave diode, utilizing the chiral bound states in a magnetic domain wall with a Dzyaloshinskii-Moriya interaction, and confirm its performance through micromagnetic simulations. Our findings open a new vista for realizing different types of pure spin-wave logic components and finally achieving an energy-efficient and hardware-reprogrammable spin-wave computer.
Jaffe, Lionel F
2008-04-12
Waves through living systems are best characterized by their speeds at 20 degrees C. These speeds vary from those of calcium action potentials to those of ultraslow ones which move at 1-10 and/or 10-20 nm s(-1). All such waves are known or inferred to be calcium waves. The two classes of calcium waves which include ones with important morphogenetic effects are slow waves that move at 0.2-2 microm s(-1) and ultraslow ones. Both may be propagated by cycles in which the entry of calcium through the plasma membrane induces subsurface contraction. This contraction opens nearby stretch-sensitive calcium channels. Calcium entry through these channels propagates the calcium wave. Many slow waves are seen as waves of indentation. Some are considered to act via cellular peristalsis; for example, those which seem to drive the germ plasm to the vegetal pole of the Xenopus egg. Other good examples of morphogenetic slow waves are ones through fertilizing maize eggs, through developing barnacle eggs and through axolotl embryos during neural induction. Good examples of ultraslow morphogenetic waves are ones during inversion in developing Volvox embryos and across developing Drosophila eye discs. Morphogenetic waves may be best pursued by imaging their calcium with aequorins.
Full-wave receiver architecture for the homodyne motion sensor
Haugen, Peter C; Dallum, Gregory E; Welsh, Patrick A; Romero, Carlos E
2013-11-19
A homodyne motion sensor or detector based on ultra-wideband radar utilizes the entire received waveform through implementation of a voltage boosting receiver. The receiver includes a receiver input and a receiver output. A first diode is connected to the receiver output. A first charge storage capacitor is connected from between the first diode and the receiver output to ground. A second charge storage capacitor is connected between the receiver input and the first diode. A second diode is connected from between the second charge storage capacitor and the first diode to ground. The dual diode receiver performs voltage boosting of a RF signal received at the receiver input, thereby enhancing receiver sensitivity.
Full-wave receiver architecture for the homodyne motion sensor
Energy Technology Data Exchange (ETDEWEB)
Haugen, Peter C.; Dallum, Gregory E.; Welsh, Patrick A.; Romero, Carlos E.
2015-09-29
A homodyne motion sensor or detector based on ultra-wideband radar utilizes the entire received waveform through implementation of a voltage boosting receiver. The receiver includes a receiver input and a receiver output. A first diode is connected to the receiver output. A first charge storage capacitor is connected from between the first diode and the receiver output to ground. A second charge storage capacitor is connected between the receiver input and the first diode. A second diode is connected from between the second charge storage capacitor and the first diode to ground. The dual diode receiver performs voltage boosting of a RF signal received at the receiver input, thereby enhancing receiver sensitivity.
Full Spectrum Conversion Using Traveling Pulse Wave Quantization
2017-03-01
range finder . While the measurement accuracy achieved is in the sub-picosecond range, the application did not require repeated measurements at very...a significantly improved Walden Figure of Merit (Figure 8). Furthermore the design builds upon the strengths of leading edge digital CMOS
Energy Technology Data Exchange (ETDEWEB)
Nazarenko, Sergey [Warwick Univ., Coventry (United Kingdom). Mathematics Inst.
2011-07-01
Wave Turbulence refers to the statistical theory of weakly nonlinear dispersive waves. There is a wide and growing spectrum of physical applications, ranging from sea waves, to plasma waves, to superfluid turbulence, to nonlinear optics and Bose-Einstein condensates. Beyond the fundamentals the book thus also covers new developments such as the interaction of random waves with coherent structures (vortices, solitons, wave breaks), inverse cascades leading to condensation and the transitions between weak and strong turbulence, turbulence intermittency as well as finite system size effects, such as ''frozen'' turbulence, discrete wave resonances and avalanche-type energy cascades. This book is an outgrow of several lectures courses held by the author and, as a result, written and structured rather as a graduate text than a monograph, with many exercises and solutions offered along the way. The present compact description primarily addresses students and non-specialist researchers wishing to enter and work in this field. (orig.)
Directory of Open Access Journals (Sweden)
Urbanczyk Guillaume
2017-01-01
Full Text Available Waves in the Ion Cyclotron (ICRF and Lower Hybrid (LH Range of Frequencies are efficient techniques respectively to heat the plasma and drive current. Main difficulties come from a trade-off between good RF coupling and acceptable level of impurities release. The mutual influence of both systems makes such equilibrium often hard to reach [1]. In order to investigate those interactions based on Scrape-Off Layer (SOL plasma parameters, a new reciprocating probe was designed allying a three tips Langmuir probe with an emissive wire. The emissive filament provides a precise measure of plasma potential [2], which can be used to calibrate Langmuir probe's results. This paper reports on experimental results obtained on EAST, where there are two ICRF antennas and two LH launchers. Among others diagnostics, the new reciprocating probe enabled to evidence the deleterious influence of ICRF power on LHWs coupling in L-mode plasmas. In areas connected with an active ICRF antenna, SOL potentials increase while densities tend to decrease, respectively enhancing impurities release and deteriorating LHWs coupling. This phenomenon has mostly been attributed to RF sheath; the one that forms on top of Plasma Facing Components (PFCs and causes ExB density convections [3]. From those experiments it seems ICRF has a strong influence on magnetically connected areas, both in the near field – influencing ICRF waves coupling – and in farther locations such as in front of LH grills. Moreover, influence of ICRF on LH system was observed both in L and H modes. Those results are consistent with RF sheath rectification process. Concerning the influence of LHWs on ICRF coupling, nothing was observed in L-mode. Besides during H-mode experiments, LHWs have been identified as having a mitigating effect on ELMs [4], which on average lowers the pedestal, increasing edge densities to the profit of ICRF waves coupling.
DEFF Research Database (Denmark)
Cortsen, Rikke Platz
2014-01-01
Alan Moore and his collaborating artists often manipulate time and space by drawing upon the formal elements of comics and making alternative constellations. This article looks at an element that is used frequently in comics of all kinds – the full page – and discusses how it helps shape spatio......, something that it shares with the full page in comics. Through an analysis of several full pages from Moore titles like Swamp Thing, From Hell, Watchmen and Promethea, it is made clear why the full page provides an apt vehicle for an apocalypse in comics....
Directory of Open Access Journals (Sweden)
Zheng-Johansson J. X.
2006-10-01
Full Text Available The electromagnetic component waves, comprising together with their generating oscillatory massless charge a material particle, will be Doppler shifted when the charge hence particle is in motion, with a velocity v, as a mere mechanical consequence of the source motion. We illustrate here that two such component waves generated in opposite directions and propagating at speed c between walls in a one-dimensional box, superpose into a traveling beat wave of wavelength Λd=vcΛ and phase velocity c2/v+v which resembles directly L. de Broglie’s hypothetic phase wave. This phase wave in terms of transmitting the particle mass at the speed v and angular frequency Ωd= 2πv/Λd, with Λd and Ωd obeying the de Broglie relations, represents a de Broglie wave. The standing-wave function of the de Broglie (phase wave and its variables for particle dynamics in small geometries are equivalent to the eigen-state solutions to Schrödinger equation of an identical system.
Fast wave power flow along SOL field lines in NSTX
Perkins, R. J.; Bell, R. E.; Diallo, A.; Gerhardt, S.; Hosea, J. C.; Jaworski, M. A.; Leblanc, B. P.; Kramer, G. J.; Phillips, C. K.; Roquemore, L.; Taylor, G.; Wilson, J. R.; Ahn, J.-W.; Gray, T. K.; Green, D. L.; McLean, A.; Maingi, R.; Ryan, P. M.; Jaeger, E. F.; Sabbagh, S.
2012-10-01
On NSTX, a major loss of high-harmonic fast wave (HHFW) power can occur along open field lines passing in front of the antenna over the width of the scrape-off layer (SOL). Up to 60% of the RF power can be lost and at least partially deposited in bright spirals on the divertor floor and ceiling [1,2]. The flow of HHFW power from the antenna region to the divertor is mostly aligned along the SOL magnetic field [3], which explains the pattern of heat deposition as measured with infrared (IR) cameras. By tracing field lines from the divertor back to the midplane, the IR data can be used to estimate the profile of HHFW power coupled to SOL field lines. We hypothesize that surface waves are being excited in the SOL, and these results should benchmark advanced simulations of the RF power deposition in the SOL (e.g., [4]). Minimizing this loss is critical optimal high-power long-pulse ICRF heating on ITER while guarding against excessive divertor erosion.[4pt] [1] J.C. Hosea et al., AIP Conf Proceedings 1187 (2009) 105. [0pt] [2] G. Taylor et al., Phys. Plasmas 17 (2010) 056114. [0pt] [3] R.J. Perkins et al., to appear in Phys. Rev. Lett. [0pt] [4] D.L. Green et al., Phys. Rev. Lett. 107 (2011) 145001.
Full PIC simulations of solar radio emission
Sgattoni, A.; Henri, P.; Briand, C.; Amiranoff, F.; Riconda, C.
2017-12-01
Solar radio emissions are electromagnetic (EM) waves emitted in the solar wind plasma as a consequence of electron beams accelerated during solar flares or interplanetary shocks such as ICMEs. To describe their origin, a multi-stage model has been proposed in the 60s which considers a succession of non-linear three-wave interaction processes. A good understanding of the process would allow to infer the kinetic energy transfered from the electron beam to EM waves, so that the radio waves recorded by spacecraft can be used as a diagnostic for the electron beam.Even if the electrostatic problem has been extensively studied, full electromagnetic simulations were attempted only recently. Our large scale 2D-3V electromagnetic PIC simulations allow to identify the generation of both electrostatic and EM waves originated by the succession of plasma instabilities. We tested several configurations varying the electron beam density and velocity considering a background plasma of uniform density. For all the tested configurations approximately 105 of the electron-beam kinetic energy is transfered into EM waves emitted in all direction nearly isotropically. With this work we aim to design experiments of laboratory astrophysics to reproduce the electromagnetic emission process and test its efficiency.
Full waveform inversion for mechanized tunneling reconnaissance
Lamert, Andre; Musayev, Khayal; Lambrecht, Lasse; Friederich, Wolfgang; Hackl, Klaus; Baitsch, Matthias
2016-04-01
In mechanized tunnel drilling processes, exploration of soil structure and properties ahead of the tunnel boring machine can greatly help to lower costs and improve safety conditions during drilling. We present numerical full waveform inversion approaches in time and frequency domain of synthetic acoustic data to detect different small scale structures representing potential obstacles in front of the tunnel boring machine. With the use of sensitivity kernels based on the adjoint wave field in time domain and in frequency domain it is possible to derive satisfactory models with a manageable amount of computational load. Convergence to a suitable model is assured by the use of iterative model improvements and gradually increasing frequencies. Results of both, time and frequency approach, will be compared for different obstacle and source/receiver setups. They show that the image quality strongly depends on the used receiver and source positions and increases significantly with the use of transmission waves due to the installed receivers and sources at the surface and/or in bore holes. Transmission waves lead to clearly identified structure and position of the obstacles and give satisfactory guesses for the wave speed. Setups using only reflected waves result in blurred objects and ambiguous position of distant objects and allow to distinguish heterogeneities with higher or lower wave speed, respectively.
Richter, Ján
2009-01-01
Aim of this master thesis is to describe the service of Full Service Leasing, as a modern form of financing and management of assets, primarily automobile fleet. Description of full service leasing is designed as a comprehensive and complete guide to support reader's position when deciding to finance and manage a fleet by this service. Whether the reader is an entrepreneur, CFO, fleet manager, new employee of leasing company, or anyone who is interested in this service, this master thesis wil...
CERN. Geneva
2005-01-01
We will present a brief introduction to the physics of gravitational waves and their properties. We will review potential astrophysical sources of gravitational waves, and the physics and astrophysics that can be learned from their study. We will survey the techniques and technologies for detecting gravitational waves for the first time, including bar detectors and broadband interferometers, and give a brief status report on the international search effort, with special emphasis on the LIGO detectors and search results.
Workflows for Full Waveform Inversions
Boehm, Christian; Krischer, Lion; Afanasiev, Michael; van Driel, Martin; May, Dave A.; Rietmann, Max; Fichtner, Andreas
2017-04-01
Despite many theoretical advances and the increasing availability of high-performance computing clusters, full seismic waveform inversions still face considerable challenges regarding data and workflow management. While the community has access to solvers which can harness modern heterogeneous computing architectures, the computational bottleneck has fallen to these often manpower-bounded issues that need to be overcome to facilitate further progress. Modern inversions involve huge amounts of data and require a tight integration between numerical PDE solvers, data acquisition and processing systems, nonlinear optimization libraries, and job orchestration frameworks. To this end we created a set of libraries and applications revolving around Salvus (http://salvus.io), a novel software package designed to solve large-scale full waveform inverse problems. This presentation focuses on solving passive source seismic full waveform inversions from local to global scales with Salvus. We discuss (i) design choices for the aforementioned components required for full waveform modeling and inversion, (ii) their implementation in the Salvus framework, and (iii) how it is all tied together by a usable workflow system. We combine state-of-the-art algorithms ranging from high-order finite-element solutions of the wave equation to quasi-Newton optimization algorithms using trust-region methods that can handle inexact derivatives. All is steered by an automated interactive graph-based workflow framework capable of orchestrating all necessary pieces. This naturally facilitates the creation of new Earth models and hopefully sparks new scientific insights. Additionally, and even more importantly, it enhances reproducibility and reliability of the final results.
Fusion plasma theory: Task 3, Auxiliary heating in tokamaks
International Nuclear Information System (INIS)
Scharer, J.E.
1989-07-01
The research that we have accomplished during the past year (1988--1989) includes the topics of ICRF fast wave waveguide coupling to H-mode profiles simulating CIT and full wave ICRF field solutions and a power conservation relation based on fundamental principles with JET and CIT heating applications. We have also published work on Fokker-Planck simulations of minority ion ICRF strong core electron sawteeth processes in JET, a publication on the effect of plasma edge density fluctuation and ponderomotive force effects on the coupling of ion Bernstein waves and a publication on the coupling of dielectric filled waveguides to plasmas in the ICRF. The analysis of ICRF H-mode coupling is crucial to the economic success of proposed ignition devices such as CIT and ITER. We have analyzed the coupling of ICRF waveguide launchers to H-mode density profiles modelled by a pedestal width and Gaussian edge variations with gradients comparable to current machines. We find that the launcher aperture spectrum, density gradients and width of the pedestal are important parameters in determining the coupling efficiency. The launcher-plasma admittance spectrum in k y -k z space is utilized to show that the H-mode launcher reflections increase when compared to the L-mode profile, but that they can be handled by launcher matching circuits and modest modifications of the H-mode profile. We plan to analyze the recent successful JET ICRF H-mode operation utilizing our formalism. We have also carried out a full wave ICRF field solution and the associated power conservation relation with expressions evaluated up to the third harmonic. We have implemented this in a computer code which utilizes invariant imbedding to solve the system of equations. 7 refs., 1 tab
Compressive full waveform lidar
Yang, Weiyi; Ke, Jun
2017-05-01
To avoid high bandwidth detector, fast speed A/D converter, and large size memory disk, a compressive full waveform LIDAR system, which uses a temporally modulated laser instead of a pulsed laser, is studied in this paper. Full waveform data from NEON (National Ecological Observatory Network) are used. Random binary patterns are used to modulate the source. To achieve 0.15 m ranging resolution, a 100 MSPS A/D converter is assumed to make measurements. SPIRAL algorithm with canonical basis is employed when Poisson noise is considered in the low illuminated condition.
Indian Academy of Sciences (India)
Lawrence
Full faith in myself. Meenakshi Banerjee. 12. Ihad my schooling at the Irish Convent, Loreto, in Asansol,. West Bengal. Perhaps the earliest memories I have are of myself as a very determined child with a deep appreciation of and inquisitiveness regarding nature although not understanding most of it at that tender age.
National Research Council Canada - National Science Library
Swanson, D. G
1989-01-01
... Swanson, D.G. (Donald Gary), D a t e - Plasma waves. Bibliography: p. Includes index. 1. Plasma waves. QC718.5.W3S43 1989 ISBN 0-12-678955-X I. Title. 530.4'4 88-34388 Printed in the United Sta...
DEFF Research Database (Denmark)
Tedd, James; Kofoed, Jens Peter; Friis-Madsen, Erik
2008-01-01
Since March 2003 a prototype of Wave Dragon has been tested in an inland sea in Denmark. This has been a great success with all subsystems tested and improved through working in an offshore environment. The project has proved the Wave Dragon device and has enabled the next stage, a production sized...
DEFF Research Database (Denmark)
Kramer, Morten; Brorsen, Michael; Frigaard, Peter
Nærværende rapport beskriver numeriske beregninger af den hydrodynamiske interaktion mellem 5 flydere i bølgeenergianlægget Wave Star.......Nærværende rapport beskriver numeriske beregninger af den hydrodynamiske interaktion mellem 5 flydere i bølgeenergianlægget Wave Star....
Centers for Disease Control (CDC) Podcasts
The Eagle Books are a series of four books that are brought to life by wise animal characters - Mr. Eagle, Miss Rabbit, and Coyote - who engage Rain That Dances and his young friends in the joy of physical activity, eating healthy foods, and learning from their elders about health and diabetes prevention. Plate Full of Color teaches the value of eating a variety of colorful and healthy foods.
Centers for Disease Control (CDC) Podcasts
2008-08-04
The Eagle Books are a series of four books that are brought to life by wise animal characters - Mr. Eagle, Miss Rabbit, and Coyote - who engage Rain That Dances and his young friends in the joy of physical activity, eating healthy foods, and learning from their elders about health and diabetes prevention. Plate Full of Color teaches the value of eating a variety of colorful and healthy foods. Created: 8/4/2008 by National Center for Chronic Disease Prevention and Health Promotion (NCCDPHP). Date Released: 8/5/2008.
International Nuclear Information System (INIS)
Bhatnagar, V.P.; Bosia, G.; Jacquinot, J.; Porcelli, F.
1993-01-01
A controlled local modification of the plasma-current profile, the safety factor q or shear (dq/dr) in a tokamak can lead to an improvement in its performance. For example, enhanced confinement in JET discharges with deep pellet injection is found to be associated with a reversal of the shear. Also, a significant control over the sawteeth behaviour in the JET tokamak has been found to occur when the shear at the q = 1 surface is modified by a dipolar-current driven by ICRF in the minority-ion heating regime. This could give a handle on the ejection of fast particles and hence on burn control in a reactor. The above sawtooth control may also be used to ease the ash removal in a reactor. When an ICRH antenna array is phased (Δφ ≠ 0 or π), the excited asymmetric k // -spectrum can drive non inductive currents by interaction of waves both with electrons (TTMP and e-Landau damping) and ions at minority (fundamental) or harmonic cyclotron resonances depending upon the scenario. Therefore, in any modeling of ICRF current drive, both (electron and ion) current drive mechanisms must be included simultaneously to correctly represent the non inductive current drive profile. To devise scenarios of shear control by minority current drive, that take advantage of the inherent electron current drive as well, we have developed a model based on earlier theories to calculate, for the first time, the two effects simultaneously. (author) 11 refs., 5 figs
Multi-parameter full waveform inversion using Poisson
Oh, Juwon
2016-07-21
In multi-parameter full waveform inversion (FWI), the success of recovering each parameter is dependent on characteristics of the partial derivative wavefields (or virtual sources), which differ according to parameterisation. Elastic FWIs based on the two conventional parameterisations (one uses Lame constants and density; the other employs P- and S-wave velocities and density) have low resolution of gradients for P-wave velocities (or ). Limitations occur because the virtual sources for P-wave velocity or (one of the Lame constants) are related only to P-P diffracted waves, and generate isotropic explosions, which reduce the spatial resolution of the FWI for these parameters. To increase the spatial resolution, we propose a new parameterisation using P-wave velocity, Poisson\\'s ratio, and density for frequency-domain multi-parameter FWI for isotropic elastic media. By introducing Poisson\\'s ratio instead of S-wave velocity, the virtual source for the P-wave velocity generates P-S and S-S diffracted waves as well as P-P diffracted waves in the partial derivative wavefields for the P-wave velocity. Numerical examples of the cross-triangle-square (CTS) model indicate that the new parameterisation provides highly resolved descent directions for the P-wave velocity. Numerical examples of noise-free and noisy data synthesised for the elastic Marmousi-II model support the fact that the new parameterisation is more robust for noise than the two conventional parameterisations.
Waves in geophysical fluids tsunamis, rogue waves, internal waves and internal tides
Schneider, Wilhelm; Trulsen, Karsten
2006-01-01
Waves in Geophysical Fluids describes: the forecasting and risk evaluation of tsunamis by tectonic motion, land slides, explosions, run-up, and maps the tsunami sources in the world's oceans; stochastic Monte-Carlo simulations and focusing mechanisms for rogue waves, nonlinear wave models, breather formulas, and the kinematics of the Draupner wave; the full story about the discovery of the very large oceanic internal waves, how the waves are visible from above through the signatures on the sea surface, and how to compute them; observations of energetic internal tides and hot spots from several field campaigns in all parts of the world's oceans, with interpretation of spectra. An essential work for students, scientists and engineers working with the fundamental and applied aspects of ocean waves.
COMPARISON STUDY OF EXPERIMENTS AND PREDICTIONS OF WAVE KINEMATICS FOR ROGUE WAVE
Directory of Open Access Journals (Sweden)
Hae Jin Choi
2018-01-01
Full Text Available To investigate the wave kinematics under the rogue wave crest, a series of experiments were performed in 2-D wave tank with the application of PIV technique to measure the velocities under the free surface. Three different prediction methods of linear extrapolation, Wheeler stretching, and modified stretching were applied to estimate water wave kinematics and compared with PIV experimental results under the highest wave crest of irregular wave trains satisfying with rogue wave criteria. Also, the cut-off frequency dependence for three prediction methods was investigated with varying spectral peak frequencies to estimate wave kinematics including velocities and accelerations in horizontal and vertical directions. It was suggested that the cut-off frequency for the reasonable prediction of the wave kinematics under the rogue wave crest could be chosen three times of spectral peak wave frequency for the linear extrapolation and higher frequency than four times of spectral peak wave frequency for Wheeler stretching and modified stretching method.
INTERFERENCE OF UNIDIRECTIONAL SHOCK WAVES
Directory of Open Access Journals (Sweden)
P. V. Bulat
2015-05-01
Full Text Available Subject of study.We consider interference of unidirectional shock waves or, as they are called, catching up shock waves. The scope of work is to give a classification of the shock-wave structures that arise in this type of interaction of shock waves, and the area of their existence. Intersection of unidirectional shock waves results in arising of a shock-wave structure at the intersection point, which contains the main shock wave, tangential discontinuity and one more reflected gas-dynamic discontinuity of unknown beforehand type. The problem of determining the type of reflected discontinuity is the main problem that one has to solve in the study of catching shock waves interference. Main results.The paper presents the pictures of shock-wave structures arising at the interaction of catching up shock waves. The areas with a regular and irregular unidirectional interaction of shocks are described. Characteristic shock-wave structures are of greatest interest, where reflected gas-dynamic discontinuity degenerates into discontinuous characteristics. Such structures have a number of extreme properties. We have found the areas of existence for such shock-wave structures. There are also areas in which the steady-state solution is not available. The latter has determined revival of interest for the theoretical study of the problem, because the facts of sudden shock-wave structure destruction inside the air intake of supersonic aircrafts at high Mach numbers have been discovered. Practical significance.The theory of interference for unidirectional shock waves and design procedure are usable in the design of supersonic air intakes. It is also relevant for application possibility investigation of catching up oblique shock waves to create overcompressed detonation in perspective detonation air-jet and rocket engines.
Wave attenuation in the Agulhas current
CSIR Research Space (South Africa)
Grundlingh, M
1995-07-01
Full Text Available The enlargement of surface wave height in the Agulhas Current, caused by waves propagating in the opposite direction to the current, is well known for its danger to large vessels traversing the Cape route. Occurrence characteristics...
DEFF Research Database (Denmark)
Bregnbæk, Susanne; Bunkenborg, Mikkel
As critical voices question the quality, authenticity, and value of people, goods, and words in post-Mao China, accusations of emptiness render things open to new investments of meaning, substance, and value. Exploring the production of lack and desire through fine-grained ethnography, this volume...... examines how diagnoses of emptiness operate in a range of very different domains in contemporary China: In the ostensibly meritocratic exam system and the rhetoric of officials, in underground churches, housing bubbles, and nationalist fantasies, in bodies possessed by spirits and evaluations of jade......, there is a pervasive concern with states of lack and emptiness and the contributions suggest that this play of emptiness and fullness is crucial to ongoing constructions of quality, value, and subjectivity in China....
From the Somigliana waves to the evanescent waves
Directory of Open Access Journals (Sweden)
Pietro Caloi
2010-02-01
Full Text Available The Rayleigh equation has real coefficients; therefore, also the case of complex conjugated roots may be explained physically. The Author proves that the Somigliana waves may be formed for Poisson ratio values until 0.30543; for gradually less rigid media, they are missing altogether and degenerate into evanescent waves.
Full Dynamic Analysis of Mooring Solution Candidates - First Iteration
DEFF Research Database (Denmark)
Thomsen, Jonas Bjerg; Ferri, Francesco
This report covers an initial full dynamic analysis of the mooring solutions for the four wave energy converters in the project “Mooring Solutions for Large Wave Energy Converters”. The analysis tends to provide the first understanding of the layouts and provide discussion on what parameters that...
DEFF Research Database (Denmark)
Kramer, Morten; Frigaard, Peter
Nærværende rapport beskriver modelforsøg udført på Aalborg Universitet, Institut for Byggeri og Anlæg med bølgeenergianlæget Wave Star.......Nærværende rapport beskriver modelforsøg udført på Aalborg Universitet, Institut for Byggeri og Anlæg med bølgeenergianlæget Wave Star....
DEFF Research Database (Denmark)
Kramer, Morten; Andersen, Thomas Lykke
Nærværende rapport beskriver modelforsøg udført på Aalborg Universitet, Institut for Vand, Jord og Miljøteknik med bølgeenergianlægget Wave Star.......Nærværende rapport beskriver modelforsøg udført på Aalborg Universitet, Institut for Vand, Jord og Miljøteknik med bølgeenergianlægget Wave Star....
Laëtitia Pedroso
2011-01-01
Ten years ago, standard issue clothing only gave CERN firemen partial protection but today our fire-fighters are equipped with state-of-the-art, full personal protective equipment. CERN's Fire Brigade team. For many years, the members of CERN's Fire Brigade went on call-outs clad in their work trousers and fire-rescue coats, which only afforded them partial protection. Today, textile manufacturing techniques have moved on a long way and CERN's firemen are now kitted out with state-of-the-art personal protective equipment. The coat and trousers are three-layered, comprising fire-resistant aramide, a protective membrane and a thermal lining. The CERN Fire Brigade' new state-of-the-art personal protection equipment. "This equipment is fully compliant with the standards in force and is therefore resistant to cuts, abrasion, electrical arcs with thermal effects and, of course, fire," explains Patrick Berlinghi, the CERN Fire Brigade's Logistics Officer. You might think that su...
DEFF Research Database (Denmark)
de Koning, Jaap; Layard, Richard; Nickel, Stephen
European unemployment is too high, and employment is too low. Over 7½ per cent of Europe's workforce is unemployed, and only two thirds of people aged 15-64 are in work. At the Lisbon summit two years ago the heads of government set the target that by 2010 the employment rate should rise from 64...... per cent to at least 70 per cent. And for older workers between 55 and 64 the employment rate should rise from 38 per cent to at least one half. These are ambitious targets. They will require two big changes: more people must seek work, and among those seeking work a higher proportion must get a job....... So we need higher participation, and (for full employment) we need a much lower unemployment rate. Can it be done? A mere glance at the experience of different European countries shows that it can. As Table 1 shows, four E.U. countries already exceed the overall target for 2010 (Britain, Denmark...
DEFF Research Database (Denmark)
Tedd, James; Kofoed, Jens Peter; Knapp, W.
2006-01-01
Wave Dragon is a floating wave energy converter working by extracting energy principally by means of overtopping of waves into a reservoir. A 1:4.5 scale prototype has been sea tested for 20 months. This paper presents results from testing, experiences gained and developments made during this ext......Wave Dragon is a floating wave energy converter working by extracting energy principally by means of overtopping of waves into a reservoir. A 1:4.5 scale prototype has been sea tested for 20 months. This paper presents results from testing, experiences gained and developments made during...... this extended period. The prototype is highly instrumented. The overtopping characteristic and the power produced are presented here. This has enabled comparison between the prototype and earlier results from both laboratory model and computer simulation. This gives the optimal operating point and the expected...... power of the device. The project development team has gained much soft experience from working in the harsh offshore environment. In particular the effect of marine growth in the draft tubes of the turbines has been investigated. The control of the device has been a focus for development as is operates...
Full traveltime inversion in source domain
Liu, Lu
2017-06-01
This paper presents a new method of source-domain full traveltime inversion (FTI). The objective of this study is automatically building near-surface velocity using the early arrivals of seismic data. This method can generate the inverted velocity that can kinetically best match the reconstructed plane-wave source of early arrivals with true source in source domain. It does not require picking first arrivals for tomography, which is one of the most challenging aspects of ray-based tomographic inversion. Besides, this method does not need estimate the source wavelet, which is a necessity for receiver-domain wave-equation velocity inversion. Furthermore, we applied our method on one synthetic dataset; the results show our method could generate a reasonable background velocity even when shingling first arrivals exist and could provide a good initial velocity for the conventional full waveform inversion (FWI).
Skeletonized wave equation of surface wave dispersion inversion
Li, Jing
2016-09-06
We present the theory for wave equation inversion of dispersion curves, where the misfit function is the sum of the squared differences between the wavenumbers along the predicted and observed dispersion curves. Similar to wave-equation travel-time inversion, the complicated surface-wave arrivals in traces are skeletonized as simpler data, namely the picked dispersion curves in the (kx,ω) domain. Solutions to the elastic wave equation and an iterative optimization method are then used to invert these curves for 2D or 3D velocity models. This procedure, denoted as wave equation dispersion inversion (WD), does not require the assumption of a layered model and is less prone to the cycle skipping problems of full waveform inversion (FWI). The synthetic and field data examples demonstrate that WD can accurately reconstruct the S-wave velocity distribution in laterally heterogeneous media.
DEFF Research Database (Denmark)
Frigaard, Peter; Kofoed, Jens Peter; Tedd, James William
2006-01-01
's first offshore wave energy converter. During this period an extensive measuring program has established the background for optimal design of the structure and regulation of the power take off system. Planning for full scale deployment of a 7 MW unit within the next 2 years is in progress. The prototype...