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 38 for “"maser"”.
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Pulsed mm-Wave electron cyclotron maser experiments
A pulsed Electron Cyclotron Maser (E. C. M.) was developed and used to generate high power mm-waves in the W-band (75-110GHz) and the G-band (150-220GHz) frequency ranges. The relativistic electron beam (R. E. B.) was produced from a field-immersed, field-emission, cold cathode. A shaped anode …
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Untersuchung von Photonenzahlzustaenden mit dem Ein-Atom-Maser
… are discussed, all of them using the one-atom-maser apparatus, which examines the interaction of single atoms of a weak thermal atomic beam with a single mode of a microwave resonator with a quality factor of 4 discussed in this thesis, shows how such a deterministic source for single photons …
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Noise analysis of circuit models representing maser operation.
Thesis: M.S., Massachusetts Institute of Technology, Department of Electrical Engineering, 1965
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Astrophysical maser radiation from Keplerian disks near active galactic nuclei
… performed that are relevant for understanding maser radiation emerging from gaseous disks at the nuclei of active galaxies. In at least one galaxy (NGC 4258), such maser radiation is observed and arises from a disk around a presumed massive black hole. The heating, cooling, and excitation …
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A molecular line and continuum study of water maser sources
… but which do lie close to otherwise isolated H2O masers. This thesis describes a search, based on catalogues of known water maser positions, for new deeply embedded cores similar to those found in S106 and M17. In addition to millimetre molecular line and submillimetre continuum observations, 22 …
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Progress towards an optimized ¹²⁹Xe / ³He Zeeman maser and a test of boost symmetry
… between co-located ¹²⁹Xe and ³He Zeeman masers that sets a stringent limit on boost-dependent Lorentz and CPT violation involving the neutron, consistent with no effect at the level of 150 nHz. In the framework of the general Standard-Model Extension, our result provides the first clean …
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An Optically-Pumped Frequency Stable Tunable Maser and Infrared-Microwave Double-Resonance Experiments in Ammonia
Microwave emission attributed to a linear cascade effect has been observed from ('14)NH(,3) optically pumped by a CO(,2) laser. The emission is tunable over the saturated homogeneous linewidth of the ground state sQ(5,4) inversion transition at 22.653 GHz. The circulating power density of the …
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Observational and theoretical studies of SiO maser polarization toward late-type evolved stars: Insights from EVPA reversal features
… responsible for the polarization of SiO masers toward late-type evolved stars continue to be a subject of debate. Possible primary sources include the local magnetic field or anisotropic pumping, while additional polarization may arise due to conversion from linear to circular modes …
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The Structure and Polarization Properties of the SiO Masers in the Extended Atmosphere of R Aquarii
Silicon monoxide (SiO) maser emission has been observed towards many late-type stars. The conditions necessary for the formation of SiO masers dictate that they be produced in a region which is inside the silicate dust formation point close to the surface of the star. Very Long Baseline …
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Propagation of radiation in astrophysical media: Gravitational lenses and astrophysical masers
… of the radiation emitted by astrophysical masers is studied by numerically solving the system of time dependent non-linear partial differential equations of radiative transfer through a masing gas. The calculations demonstrate for the first time how oscillations, with periods which are …
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EVLA imaging of methanimine and hydrogen cyanide in Arp 220
… also confirmed that the\meth\line is most like a maser; this represents the first independent confirmation of the only \meth\ maser ever detected. This \meth\ maser was found to have an isotropic luminosity of 5$L_\odot$, close to the luminosity (12$L_odot$) of a formaldehyde maser in Arp 220, and …
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Measurement of Magnetic Fields From Linear Polarization of Dust Emission
… monitoring the time variability of polarized SiO maser emission (RLeo, Orion IRc2) and studying the linear polarization of quasars.
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The radiation mechanism of fast radio bursts
… coherent radiation mechanisms are considered - maser and the antenna mechanism. We use the observed properties of the repeater FRB 121102 to constrain the plasma conditions needed for these two mechanisms. We have looked into a wide variety of maser mechanisms operating in either vacuum or …
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The transfer of polarized radiation in astrophysical masers in the presence of magnetic fields
Polarized emission from astrophysical masers can provide important information about physical conditions in both star forming and circumstellar environments. Calculations are performed which give the spectra of the emergent maser radiation for different magnetic fields, radiative intensities, decay …
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Development of Software to Measure the Gravitational Redshift with RadioAstron
… highly elliptical orbit. Utilizing the onboard H-maser frequency standard along with a Doppler compensation scheme that minimizes systematics, the gravitational redshift is anticipated to be determined with a relative accuracy of 10^-5. A third-order dynamical model has been implemented to predict …
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Continuously tapered dielectric matching transitions for waveguides
… waveguides into dielectric filled waveguides for maser work or into dielectric rod antennas. Also dielectric loading has been shown to improve the performance of the ferrite isolators.</p> <p>The dielectric matching transitions that have been analyzed in the literature are of the stepped type. The …
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Stochastic electron trajectories and wave interaction in relativistic gyro-traveling wave amplifiers
… which take advantage of the cyclotron maser instability to produce coherent electromagnetic (EM) radiation from electrons gyrating in an external magnetic field and interacting with fast traveling waves. For high power applications, gyrodevices often require relativistic electron beams …
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