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 14 of 14 for “"TWT"”.
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Design of an overmoded W-Band coupled cavity TWT
… of a novel, overmoded Traveling Wave Tube (TWT) capable of producing power levels in excess of 100 Watts at frequencies of 100 GHz and above. High power sources at frequencies from the W-Band (70 to 110 GHz) to the THz frequency range are needed for numerous applications including radar, …
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Design and test of a 94 GHz overmoded traveling wave tube amplifier
… test of an overmoded W-band Traveling Wave Tube (TWT). The TWT was designed to operate in the rectangular TM31 cavity mode at 94 GHz. The unwanted lower order, TM₁₁ and TM₂₁, modes were suppressed using selectively placed aluminum nitride dielectric loading. Simulations in 3-D CST Particle Studio …
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A 140 GHz gyro-amplifier using a confocal waveguide : theory and experimental results
… of a gyrotron travelling-wave-tube (TWT) amplifier at 140 GHz. The gyro-TWT uses the HE06 mode of a confocal geometry as its operating mode. The linear and nonlinear theory of the confocal waveguide is presented, along with a quasi-optical approach for describing the modes of a …
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A novel wideband gyrotron travelling wave amplifier
… quasioptical Gyrotron Traveling Wave Tube (gyro-TWT) amplifier and the first Vacuum Electron Device (VED) with a Photonic Band Gap (PBG) structure. The theory and experimental results from two other quasioptical gyrotron oscillator experiments are also presented. The gyro-TWT amplifier at 140 GHz …
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High linearity broad-band helix TWTs
Helix travelling-wave tubes (TWTs) are extensively employed as final power amplifiers in satellites. These applications demand low spectral noise and high efficiency across a broad band. Research has been carried out to achieve these criteria in a helix TWT design. A deeper understanding has been …
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Design of a 250 GHz gyrotron amplifier
… 250 GHz, 1 kW gyrotron traveling wave tube (gyro-TWT) amplifier with gain exceeding 50 dB. Calculations show that the amplifier will operate at 32 kV, 1 A with a saturated gain of 60 dB, an output power of 1 kW and a gain bandwidth of 3 GHz. The amplifier uses a novel photonic band gap (PBG) …
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Characterizing resistance of Erysiphe necator to fungicides belonging to the quinone outside inhibitors and demethylation inhibitors
… with increased resistance had either a TTT or TWT genotype; TWT indicated the presence of both wildtype and mutant alleles. Cyp51 was expressed 1.4 to 19 times more in mutants than in wildtype. It is not known whether the significant differences in cyp51 expression level among isolates and …
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Stratigraphic and structural interpretation of seismic reflection data across selected sections of the Kaapvaal Craton
… acquired by the vibroseis method to 6 seconds TWT, and totaling ~720 km in length. New stratigraphic and structural features are identified across three main regions: the Kaapvaal Craton's western margin, the northern margin or Bushveld lines (flanking the Thabazimbi-Murchison Lineament and …
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ΜΕΛΕΤΗ ΚΑΙ ΥΠΟΛΟΓΙΣΜΟΣ ΤΗΣ ΕΠΙΘΥΜΗΤΗΣ ΠΡΟΠΑΡΑΜΟΡΦΩΣΗΣ ΓΙΑ ΤΗΝ ΔΙΟΡΘΩΣΗ ΤΗΣ ΕΙΣΑΓΟΜΕΝΗΣ ΠΑΡΑΜΟΡΦΩΣΗΣ ΣΕ ΜΗ ΓΡΑΜΜΙΚΟΥΣ ΠΟΛΥΕΠΙΠΕΔΟΥΣ ΨΗΦΙ...
… NONLINEAR DISTORTION. AS IS KNOWN, TWT AMPLIFIERS, USED IN A SATELLITE TRANSPONDER OR A TERRESTRIAL REPEATER, ARE USUALLY WORKING NEAR SATURATION BECAUSE OF HIGH SYSTEM GAIN REQUIREMENTS [3,4]. IN THIS MODE OF OPERATION THE AMPLIFIEREXHIBITS AM/AM AND A CONVERSION EFFECTS, CAUSING …
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Estimation of seismic parameters from multifold reflection seismic data by generalized linear inversion of Zoeppritz equations
… mid-point (CMP) geometry, and two-way travel (twt) time. The equations in the time-offset domain have five independent variables that enable estimation of P- and S-wave velocities and density ratio for the upper and lower layers. The linearity and uniqueness of the inversion are investigated by …
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Correlative Analysis of Sperm Morphology, Seminiferous Epithelial Area and Testis Weight in the Boar
… positive correlation between testicular weight (TWT) and SEA while abnormal boars did not. Therefore, it appears that the SEA may be a relatively good indicator to determine testicular function. Regarding clinical evaluation of boars, the strong correlation of PD frequency with reduced SEA and …
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A 250 GHz photonic band gap gyrotron amplifier
… of a novel gyrotron traveling-wave-tube (TWT) amplifier at 250 GHz. The gyrotron amplifier designed and tested in this thesis has achieved a peak small signal gain of 38 dB at 247.7 GHz, with a 32 kV, 0.35 A electron beam and a 8.9 T magnetic field. The instantaneous -3 dB bandwidth of the …
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Quadrupole Strong Focusing for Space-Charge Dominated Electron Beams in Traveling-Wave Tubes
… quadrupole focusing lattices for high-frequency TWTs is presented. This work is motivated by recent work performed at the Naval Research Laboratory (NRL) which demonstrated an advantageous case for strong focusing employing a Halbach quadrupole lattice. Using realistic Permanent Magnet Quadruple …
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Numerical and experimental study of flow in a gas turbine chamber.
… Technology (TPT) and a Thermal Wind Tunnel (TWT). Both methods confirmed that the blade specimen with angle of injection of 45°, blowing ratio of BR=2 (which corresponds to 1000cm[3]/min), cooling holes diameter D=lmm and 42 holes developed a better film cooling effectiveness compared …