Development and modeling of a sliding arc type intermediate plasma source with magnetic field and notched cylindrical cathode.

Name: Rafael Pires Ribeiro
Type: PhD thesis
Publication date: 11/08/2020

Namesort descending Role
Alfredo Gonçalves Cunha Advisor *

Examining board:

Namesort descending Role
Alfredo Gonçalves Cunha Advisor *
Davi Cabral Rodrigues Internal Examiner *
Gilberto Petraconi Filho External Examiner *
Gustavo Paganini Canal External Examiner *
José Rafael Cápua Proveti External Examiner *

Summary: The present work is dedicated to the development of an improved model of gliding arc (GA). The gliding arc is a non-stationary plasma, maintained by an electrical discharge, which develops between two parallel divergent electrodes; blown by a gas stream. It can be powered by a DC or alternating voltage source. The electric arc starts in the region of the shortest distance between the electrodes, with high electric current and, as it extends, the current decreases with the increase in voltage, until its interruption. Then, the arc restarts again, thus establishing a repetitive process. A new version of GA keeps the arc stable at low current, after reaching a certain length, and uses a magnetic field to move the arc. This plasma type was initially called plasma disk or magnetic gliding arc (MGA). This work deals with the development and improvement of a magnetic gliding arc (MGA), WHERE a significant change was made in the cathode geometry, which allowed to considerably increase the arc stability, reaching an arc length of 40 mm, plasma disc diameter of 102.0 mm, and currents I from 300 to 400 mA. For arc rotation characterization, a low-cost electro-optical device was developed, using LDRs, to determine the arc rotation frequency f. It was also deduced a theoretical equation that links f, I, magnetic field B and the cathode diameter D, among other parameters that can be approximated by an approximately constant factor, using the frequency measured by the previous apparatus. From these variables, it was possible to graphically obtain a linear behavior, that is, a line that passes through the origin. This makes it possible to represent the general experimental behavior of different MGAs, which operate in the air at atmospheric pressure. The experimental results of the developed MGA are very close to the theoretical model, and it is also possible to estimate the diameter d of the arc near the cathode.

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