Global ETD Search
Search theses and dissertations gathered from participating repositories worldwide. Every result links back to the library that holds it. No account is needed.
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Showing 1 to 20 of 35 for “"mode conversion"”.
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Mode conversion current drive experiments on Alcator C-Mod
… (FW) in the Ion Cyclotron Range of Frequency can mode convert to shorter wavelength modes at the Ion-Ion hybrid layer, leading to localized electron heating and current drive. Due to k1l upshifts associated with the poloidal magnetic field, only small net driven currents were predicted from mode …
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Mode conversion and wave -particle interaction processes in the solar wind
… the Alfven wave couples to the slow magnetosonic mode. In the inner corona, it seems that these two possible ways of coupling do not occur simultaneously in the same structures, while beyond 5--10 R⊙ , where the plasma beta is about unity, both of them can operate at the same time and the …
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Studies of ICRF mode conversion with phase contrast imaging and full-wave simulations in Alcator C-Mod
… resonance between the cyclotron resonances. The mode converted waves are of interest as actuators to optimize plasma performance through current drive and flow drive. Numerical simulations are essential to describe these processes accurately in a realistic tokamak geometry, and it is important …
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Characterization and modeling of multilayer interconnections for high-speed digital systems
… matrix method and by experiments of large scale models. It is observed that electromagnetic waves that propagate in multilayer interconnections can excite other electromagnetic modes when they encounter discontinuities. This phenomenon, the excitation of different electromagnetic modes at …
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Sparse signal representation based algorithms with application to ultrasonic array imaging
… one-layer imaging we also address the problem of mode conversion. We propose a sparse signal representation based method for imaging solid materials in the presence of mode conversion phenomenon. In the case of two-layer imaging we model the signal propagation effect using Huygens principle and …
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Evaluation of on-chip integration of magneto-optic isolators
… designs for waveguide isolator (nonreciprocal mode conversion and nonreciprocal phase shift) have both merits and short comings for integration. The advances in integration techniques and materials related developments in the last decade are a big step towards monolithic integration of isolator …
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2X-Thru, 1X-Reflection, and Thru-Line de-embedding: Theory, sensitivity analysis, and error corrections
… to non-ideal manufacturing effects of non-zero mode conversion terms, as well as the asymmetric, and manufacturing variations. The validations are performed on both theory and self-error reduction through simulation and measurements cases. The 2X-Thru de-embedding (2XTD) is discussed in details. …
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Numerical simulation of wave-plasma interactions in the ionosphere
… the effect of 2D density inhomogeneity on the O-mode to Z-mode conversion process and thus the shape of the conversion window, and the influence of EM wave polarisation and frequency on the growth of density irregularities. The O-to-Z-mode conversion process was shown to be responsible for a …
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Optimization and design of radio frequency piezoelectric MEMS resonators
… based on fundamental symmetric (S0) Lamb mode have shown great promise because they can offer high phase velocities (10,000 m/s), low dispersive phase velocity characteristic, small temperature-induced frequency drift, low motional resistance, and monolithic integration compatibility with …
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Identifying Signatures of Plasma Waves and Reconnection Associated with Kelvin-Helmholtz Activity
… Previous studies have also shown that mode conversion at the magnetopause can generate kinetic Alfvén wave (KAW) activity. Both magnetic reconnection and plasma wave activity can heat plasma. In this thesis we look for new cases of Kelvin-Helmholtz Instability (KHI) from Cluster …
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Beiträge zur Dispersionskompensation basierend auf der Modenkonversion in höhere Moden und der Ausbreitung dieser Moden in Lichtwellenleitern
… special propagation properties of higher order modes in custom-designed optical fibers. After a short introduction of state-of-the-art dispersion techniques and their parameters (chapter 2) the modeling and calculation of propagation properties of a particular mode in an optical fiber with an …
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Physics of the helicon antenna on the prototype materials exposure experiment
… has been operating in a high-density “helicon-mode” of operation. The helicon mode of operation is classified by an increase in target on-axis electron density (6e19 m^-3) and a decrease in electron temperature (2 – 3 eV) during a helicon pulse. This transition is observed when Deuterium gas is …
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Design of elastic metamaterials
… showed that using frame bending/stretching mode is more effective than applying beam bending mode to broaden bandgap. Furthermore, it is found that adding internal resonant components could enlarge the bandgap. The single negativity metamaterials were validated by numerical simulations of …
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Characterization of S-bend optical waveguides fabricated by impurity- and vacancy-induced layer disordering
… process is less than 300 $\mu$m for near single-mode guides. In addition, vacancy-induced layer disordering (VILD) of the native quantum-well region is investigated and is shown to increase the band gap to a point at which the material is low-loss for radiation generated by a laser made from the …
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Atomic alkali lasers pumped by the dissociation of photoexcited alkali-rare gas collision pairs
… (XPALs) attractive candidates for the spatial mode conversion of laser diode arrays with nominal linewidths of 2 nm in order to produce high quality (M2 1) beams. Quantum e ciencies exceeding 98% have been measured and may potentially mitigate heat extraction issues associated with high power, …
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Mode conversation losses in overmolded millimeter wave transmission lines
… transmission lines propagating the HE,1 mode with a high waveguide radius to wavelength ratio (a/X), the transmission line loss is predominantly a result of mode conversion in components such as miter bends. The theory for determining losses in miter bends though is only approximate, and …
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Rotation studies in fusion plasmas via imaging X-ray crystal spectroscopy
… intrinsic rotation in enhanced confinement modes, lower hybrid wave induced rotation and ICRF mode conversion flow drive. Each of these methods is discussed in detail with reference to how they might be used in next generation tokamaks.
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Pulsed mm-Wave electron cyclotron maser experiments
… optimum cavity Q, resonant frequencies, relative mode density, reflection coefficients and mode conversion in the output coupler. Two pulsed conventional field coils were used; coil#1 (maximum B-field : 9T) produced the uniform intra-cavity magnetic field and coil#2 (maximum B-field : 1T) acted as …
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I. Resonant two-proton reabsorption by exition-polaritons in cuprous chloride films ; II. Heat pulse progration across metal/sapphire interfaces ; III. Phonon focusing in piezoelectric crystals
… of transverse phonons near the critical cone for mode conversion from bulk transverse waves to longitudinal waves along the surface. It is found to be dependent on surface orientation and is very sensitive to surface quality. A theory by A. Every is described in which this feature is due to a …
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Study of phonon transmission through solid-solid interfaces and superlattices by phonon imaging
… phonons close to the critical cone for mode conversion of transverse to longitudinal waves at the diamond surface. The process is mediated by pseudo-surface waves, and provides information about the quality of the diamond surface and the mechanical bonding of the copper/diamond …
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