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Plasma and Beam Physics

Old Dominion University

2006

Articles 1 - 4 of 4

Full-Text Articles in Physical Sciences and Mathematics

Plasma Emission Redistribution In A Single Cylce Of A Pulsed Dc Magnetron, W. Zhu, G. Buyle, J. Lopez, S. Shanmugmurthy, A. Belkind, K. Becker, R. De Gryse Jan 2006

Plasma Emission Redistribution In A Single Cylce Of A Pulsed Dc Magnetron, W. Zhu, G. Buyle, J. Lopez, S. Shanmugmurthy, A. Belkind, K. Becker, R. De Gryse

Physics Faculty Publications

Time-resolved images of the optical emissions from a pulsed dc titanium target planar rectangular sputtering magnetron plasma were taken using Argon spectral filters and a Roper Scientific ICCD camera with a time resolution of 0.05-0.2 μs. At the beginning of the 'on-time', when the power is turned on, the discharge initially starts preferentially in two opposite curved sections ('cross corners') of the magnetron race track, where it exhibits the most intense plasma emissions. During the rest of the 'on-time', the emissions from the straight sections of the race track of the magnetron are always slightly more intense than the emissions …

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Plasma Treatment Of Bulk Niobium Surfaces For Srf Cavities, M. Rašković, L. Vuškovic, S. Popović, L. Phillips, A. -M. Valente-Feliciano, S. B. Radovanov, L. Godet Jan 2006

Plasma Treatment Of Bulk Niobium Surfaces For Srf Cavities, M. Rašković, L. Vuškovic, S. Popović, L. Phillips, A. -M. Valente-Feliciano, S. B. Radovanov, L. Godet

Physics Faculty Publications

Two types of electric discharges were used to demonstrate the validity of plasma surface treatment for superconducting radio-frequency (SRF) cavities. The experiments were performed on disc-shaped Nb samples and compared with identical samples treated with buffer chemical polishing (BCP) techniques. Surface analysis indicates comparable or superior properties of plasma-treated samples. These promising results are still preliminary and additional work is in progress.

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Electron Bernstein Wave Simulations And Comparison To Preliminary Nstx Emission Data, Josef Preinhaelter, Jakub Urban, Pavol Pavlo, Gary Taylor, Steffi Diem, Linda L. Vahala, George Vahala Jan 2006

Electron Bernstein Wave Simulations And Comparison To Preliminary Nstx Emission Data, Josef Preinhaelter, Jakub Urban, Pavol Pavlo, Gary Taylor, Steffi Diem, Linda L. Vahala, George Vahala

Electrical & Computer Engineering Faculty Publications

Simulations indicate that during flattop current discharges the optimal angles for the aiming of the National Spherical Torus Experiment (NSTX) antennae are quite rugged and basically independent of time. The time development of electron Bernstein wave emission (EBWE) at particular frequencies as well as the frequency spectrum of EBWE as would be seen by the recently installed NSTX antennae are computed. The simulation of EBWE at low frequencies (e.g., 16 GHz) agrees well with the recent preliminary EBWE measurements on NSTX. At high frequencies, the sensitivity of EBWE to magnetic field variations is understood by considering the Doppler broadened electron …

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Dynamics Of An Atmospheric Pressure Plasma Plume Generated By Submicrosecond Voltage Pulses, Xinpei Lu, Mounir Laroussi Jan 2006

Dynamics Of An Atmospheric Pressure Plasma Plume Generated By Submicrosecond Voltage Pulses, Xinpei Lu, Mounir Laroussi

Electrical & Computer Engineering Faculty Publications

Nonequilibrium plasmas driven by submicrosecond high voltage pulses have been proven to produce high-energy electrons, which in turn lead to enhanced ionization and excitations. Here, we describe a device capable of launching a cold plasma plume in the surrounding air. This device, "the plasma pencil," is driven by few hundred nanosecond wide pulses at repetition rates of a few kilohertz. Correlation between current-voltage characteristics and fast photography shows that the plasma plume is in fact a small bulletlike volume of plasma traveling at unusually high velocities. A model based on photoionization is used to explain the propagation kinetics of the …

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