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A technique which employs a laser-excited optical resonator has been developed to measure the electron density distribution, both temporal and spatial, in the collapse stage of a fast Z-pinch discharge. The resonator device has an experimentally determined time resolution of better than 0.05 µsec and is suitable for measuring electron densities in excess of 5 • 10¹⁶ /Lʎ cm⁻³, where L is the length of the plasma in cm and ʎ is the wavelength of the laser in microns. A novel feature of this instrument is the use of an unstable optical resonator. The technique is applied to a discharge in argon at filling pressures of 100 and 1000 µHg. The temporal and radial electron density distributions obtained exhibit several interesting features which are discussed from the point of view of the collapse process. / Science, Faculty of / Physics and Astronomy, Department of / Graduate

published_or_final_version / Electrical Engineering / Master / Master of Philosophy

In J.D. Jackson's Classical Electrodynamics textbook, the analysis of Dirac's charge quantization condition in the presence of a magnetic monopole has a mathematical omission and an all-too-brief physical argument that might mislead some students. This paper presents a detailed derivation of Jackson's main result, explains the significance of the missing term, and highlights the close connection between Jackson's findings and Dirac's original argument. (C) 2016 Sharif University of Technology. All rights reserved.

A dissertation submitted to the Faculty of Engineering and the Built Environment, University of the Witwatersrand, in ful lment of the requirements for the degree of Master of Science in Engineering. Johannesburg, 2015 / During a cloud to ground lightning event a charge centre within the storm cloud is discharged. The discharge of a charge centre within the cloud leads to a change in the electric eld radiated by the charge centre. It is theoretically possible to infer the lightning current from the derivative of the electric eld. It is only possible to infer the lightning current from the electric eld data where the noise is comparatively much smaller than the electric eld data. The changing electric elds for a lightning event that occurred on the 3rd January 2015 13:15:13 were recorded by a at plate electric eld sensor with a passive integrator. The oscilloscope used to capture the electric eld data has a relatively large measurement noise and a low resolution. A low pass digital lter was applied to the recorded electric eld data to reduce the e ects from the high frequency noise. The lightning strokes were recorded by the South African Lightning Detection Network. The Lightning Detection Network data is used to obtain the distance of the lightning event from the sensor, to scale the inferred lightning current. The Lightning Detection Network also provides a lightning peak current measurement to compare to the peak current inferred from the electric eld data. The lightning stroke current was inferred from the electric eld recording for various bandwidths of the low pass lter. Inconsistent changes to the inferred lightning stroke current as the lter bandwidth is changed shows that the frequency components for each stroke di ers. The peak stroke current was not constant for any lter bandwidth range implying that the measurement noise is relatively too large. The case study presented demonstrates that with a relatively large noise magnitude (3 to 4 discrete steps of the digital recording) compared to the electric eld signal (21 discrete steps) it is di cult to accurately infer the lightning current from the electric elds recorded. / MT2017

Thesis. 1976. Ph.D. cn--Massachusetts Institute of Technology. Dept. of Mechanical Engineering. / Vita. / Includes bibliographical references. / by Peter W. Huber. / Ph.D.cn

by Raymon, Wai-man Chan. / "March 1999." / Thesis (Ph.D.)--Chinese University of Hong Kong, 1999. / Includes bibliographical references. / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Mode of access: World Wide Web. / Abstracts in English and Chinese. / by Raymon, Wai-man Chan.

Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Chemical Engineering, 1979. / MICROFICHE COPY AVAILABLE IN ARCHIVES AND SCIENCE. / Bibliography: leaves 122-126. / by Peter Michael Hirsch. / M.S.

Thesis (M. Phil.)--University of Hong Kong, 1974. / Mimeographed.