Motion studies of high current arcs using an optical fibre array imaging system

This paper presents an integrated portable measurement system for thestudy of high speed and high temperature unsteady plasma flows such as thosefound in the vicinity of high current switching arcs. The system permits direct andnon-intrusive measurement of arc light emission images with a capture rate of 1million images per second (1MHz), and 8 bit intensity resolution. Novel softwaretechniques are reported to measure arc trajectories. Results are presented on singlehigh current (2kA) discharge events where the electrode and arc runner surfaces areinvestigated using 3D laser scanning methods; such that the position of the arc rootson the runner can be correlated to the measured trajectories. The results showevidence of the cathode arc root stepping along the arc runners<br/

Motion studies of high current arcs using an optical fibre array imaging system

This paper presents an integrated portable measurement system for thestudy of high speed and high temperature unsteady plasma flows such as thosefound in the vicinity of high current switching arcs. The system permits direct andnon-intrusive measurement of arc light emission images with a capture rate of 1million images per second (1MHz), and 8 bit intensity resolution. Novel softwaretechniques are reported to measure arc trajectories. Results are presented on singlehigh current (2kA) discharge events where the electrode and arc runner surfaces areinvestigated using 3D laser scanning methods; such that the position of the arc rootson the runner can be correlated to the measured trajectories. The results showevidence of the cathode arc root stepping along the arc runners<br/

Motion studies of cathode roots in high current arcs using an optical fibre array based imaging system

This paper presents an integrated portable measurement system for the study of high speed and high temperature unsteady plasma flows such as those found in the vicinity of high current switching arcs. The system permits direct and non-intrusive measurement of arc light emission images with a capture rate of 1 million images per second (1MHz), and 8 bit intensity resolution. Novel software techniques are reported to measure arc trajectories. Results are presented on single high current (2kA) discharge events where the electrode and arc runner surfaces are investigated using 3D laser scanning methods; such that the position of the arc roots on the runner can be correlated to the measured trajectories. The results show evidence of the cathode arc root stepping along the arc runners, and regions of where the arc runner is eroded by a stationary arc

Protons as Intercellular Messengers

Muscle contractions are driven by neurotransmitters released at neuromuscular junctions. In this issue, Beg et al. (2008) report that protons, in the absence of neurotransmitters and neurons, can stimulate muscle contractions involved in the defecation cycle of the worm Caenorhabditis elegans. Their results identify protons as a new intercellular messenger and suggest that proton-mediated intercellular communication may be a widespread phenomenon

On the Treatment of Neutrino Oscillations Without Resort to Weak Eigenstates

We discuss neutrino oscillations in the framework of the quantum field theory without introducing the concept of neutrino weak eigenstates. The external particles are described by wave packets and the different mass eigenstate neutrinos propagate between the production and detection interactions, which are macroscopically localized in space-time. The time-averaged cross section, which is the measurable quantity in the usual experimental setting, is calculated. It is shown that only in the extremely relativistic limit the usual quantum mechanical oscillation probability can be factored out of the cross section.Comment: LaTeX-18pages, JHU-TIPAC-930011,DFTT 22/9

Graph polynomials and statistical physics

Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Mathematics, 2007.Includes bibliographical references (p. 53-54).We present several graph polynomials, of which the most important one is the Tutte polynomial. These various polynomials have important applications in combinatorics and statistical physics. We generalize the Tutte polynomial and establish its correlations to the other graph polynomials. Finally, our result about the decomposition of planar graphs and its application to the ice-type model is presented.by Jae Ill Kim.S.M

A theorem for the beam splitter entangler

It is conjectured that the an entanglement output states from a beam splitter requires the nonclassicality in the input state(M.S. Kim, W. Son, V. Buzek and P. L. Knight, Phys. Rev. A, 65, 032323(2002)). Here we give a proof for this conjecture.Comment: Two relevant literatures added. To appear in Phys. Rev.

Neutrino Wave Packets in Quantum Field Theory

We present a model of neutrino oscillations in the framework of quantum field theory in which the propagating neutrino and the particles participating to the production and detection processes are described by wave packets. The neutrino state is a superposition of massive neutrino wave packets determined by the production process, as naturally expected from causality. We show that the energies and momenta of the massive neutrino components relevant for neutrino oscillations are in general different from the average energies and momenta of the propagating massive neutrino wave packets, because of the effects of the detection process. Our results confirm the correctness of the standard expression for the oscillation length of extremely relativistic neutrinos and the existence of a coherence length.Comment: 25 page