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 59 for “"Emittance"”.
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An emittance scanner for high-intensity, low-energy ion beams
… injected into the cyclotron needs to have a low emittance (a figure of merit for the beam quality). This is where the need for a way to measure our beam's emittance arises. This thesis covers the process of designing, fabricating, assembling, and commissioning an emittance scanner. The main …
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Beam emittance measurements in the SPC2 injection beamline at iThemba LABS
Beam emittance is a property of a charged particle beam in a particle accelerator that is used to estimate the beam quality. It is length-based measure of the average spread of particle coordinates in position and momentum phase space. This attribute makes emittance a crucial beam parameter that …
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Low emittance electron beam production and characterization with a 17 GHz photocathode RF gun
… "bead hang" technique. A beamline, including an emittance compensating solenoid, beam imaging system, and energy spectrometer, was designed and built for testing these guns. The RF guns were powered with up to 4 MW of microwave power from a 25 MW, 17 GHz relativistic klystron amplifier built in …
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Thermal emission measurement and calibration
… setup and experimental procedures for emittance measurements using a Fourier transform infrared spectrometer. We calibrate the FTIR measurement system using measurements of a blackbody source at two temperatures to obtain the true emittance and absolute spectral radiance of our samples.
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TRANSVERSE CHARACTERIZATION AND CONTROL OF BEAMS WITH SPACE CHARGE
… are presented for measurement of transverse emittance for beams with space charge, an important quality indicator of transverse phase space. It is also discussed the experimental work on orbit characterization and control done for space charge dominated beams of the University of Maryland …
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Modeling of electroluminescence in InSb quantum wells and inversion asymmetric effects
… expression for electroluminescence spectral emittance based entirely on quantum mechanical model, unlike the more usual semi classical models used in semiconductor physics. The final expression for the spectral emittance has a different dependence compared to the semi classical expression, …
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High-brightness electron beams from a DC, high-voltage, GaAs photoemission gun
… gun and used it to measure the rms transverse emittance and rms momentum spread of the highly-charged, short-duration electron bunches it generates. We report these measurements as functions of microbunch charge for different beam radii, pulse lengths, and voltages/field gradients at the …
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Development of a 300 KV DC High Voltage Photogun and Beam Based Studies of Alkali Antimonide Photocathodes
… the quality of the electron beams. The thermal emittance of the electron beam was measured with various conditions: different gun bias voltages, different laser spot sizes, and photocathodes with different substrate materials. It has been hypothesized that the photocathode surface roughness …
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Investigations of the physical properties of photoemission polarized electron sources for accelerator applications
… system was studied by measuring the beam emittance as a function of current. Finally, the thermal properties of GaAs were investigated by measuring the beam emittance as functions of the excitation laser wavelength and the laser spot size.
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Measurement of some radiative properties of solar absorber materials
… a Golay-cell detector. The overall error in the emittance values measured is estimated to be ± 5%. Using the emissometer all the samples in (ii) above were studied. The directional emittance behaviour of the metals and the non-selective absorbers agree well with theoretical predictions and with …
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Detailed thermal analysis of a thin-shell, spherical radiometer in Earth orbit
… detector consists of independent models of emittance, long wavelength absorptance; and solar absorptance. The emittance as a function of temperature was determined from the Davisson, and Weeks analytical expression. The long wavelength absorptance as a function of incident angle, wavelength, …
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Design and testing of an electron cyclotron resonance heating ion source for use in high field compact superconducting cyclotrons
… The two most important beam parameters are emittance and beam current. The emittance of the beam is a measurement of the rate of beam spread along the path of the beam and beam current is a measurement of the energy and quantity of particles within a charged particle beam. This thesis …
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Timing Diagnostics and Coherent Harmonics from a test-FEL
… of 200 pC of electrons with a normalized emittance of 5.5 mmmrad and a quantum efficiency of 1.1 10-4. To ensure the electron bunch overlap with the 500 fs seed laser pulse and to measure the bunch length, an electro-optical spectral decoding setup was built. The bunch length of about 1 ps …
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Photonic crystals for high temperature applications
… as selective thermal emitters that approach the emittance of a blackbody below a cutoff wavelength, and zero emittance above the cutoff. The theory behind the enhancement of thermal emission is explored, leading to design handles that enable optimization for different applications. The …
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Electron Beam Diagnostic at the ELBE Free Electron Laser
… #2 describes measurements of the transverse emittance we did at ELBE including an explanation of the experimental methods and the measurement error analysis. The transverse emittance was measured with the multislit method in the injector where the beam is space charge dominated. The …
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Inverse Design and Optimization Methods for Thermophotovoltaic Emitters made of Tungsten Gratings
… systems. These gratings work by altering the emittance spectrum incident on the photovoltaic cell to better match the band gap of the cell. Photons at slightly higher energies than the band gap are the most efficient as they generate electron-hole pairs while minimizing thermalization losses. …
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High Power Cyclotrons: The Bridge Between Beyond the Standard Model Physics, Computation, and Medical Applications
… an Ht ion source with the necessary excellent emittance parameters and low contamination of non-Ht ions. In this thesis, we report results from a multi-cusp ion source that meets these requirements and produces a record level of high purity, low emittance Ht current. The second has been to …
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Radiative Heat Transfer for Emitting, Absorbing and Scattering Planar Media
… path length concept. The total hemispherical emittance for a single gas species in an isothermal planar layer with scattering particulate is developed. Exact results for a gas species of H(,2)O or CO(,2) are presented. A factor to incorporate scattering is presented to more easily utilize the …
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Inverse Compton Light Source: A Compact Design Proposal
… gun allows for an extremely small transverse emittance, increasing the brilliance of the resulting X-ray source. In order to achieve sufficiently small emittances, optimization was done regarding both the geometry of the gun and the initial electron bunch distribution produced off the cathode. …
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