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Title: A study of electron dynamics in a single and dual frequency inductively coupled plasma system
Author: Zaka-ul-Islam, Mujahid
Awarding Body: Queen's University Belfast
Current Institution: Queen's University Belfast
Date of Award: 2012
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The single and dual frequency ICPs are studied in this thesis, mostly in oxygen; a simple electronegative gas. The diagnostics used here include; PROES, laser photodetachment and, Hairpin and Langmuir probes. Many issues of the fundamental understanding were investigated which include; the influence of the electronegativity on the electron density, E-H mode transition, collisionless heating, RF biased ICPs and the pulsed ICPs. The changes in the electronegativity are found here to be related to the heating mechanisms in the plasma. ICPs are well known to operate in E or H mode, depending on the applied power. The PROES measurements showed that both capacitive and inductive power couplings are simultaneously present in stable E and H modes, close to the transition. The individual contribution of capacitive and inductive power is also estimated here, using some new techniques. In pulsed ICPs, E and H like modes with simultaneous contribution of the capacitive and inductive couplings are also observed. The PROES measurements in the H-mode of ICPs, operated in the collisionless pressure regime, shows axially two maxima structure in the discharge, possibly because of the negative power absorption in the middle of the ICPs. The spatio-temporal excitation measurements in a RF biased ICPs (or dual frequency ICPs) showed that the coupling of the bias with tile capacitive coupling of the coil play a . significant role in the electron heating. The power and pressure regime where RF bias significantly influences the electron density and heating, is identified. The measurements also indicate the limitations of the independent control of the ion flux and energy. The phase between the ICP and bias could be used to decrease or enhance the influence of bias on electron heating. The electron density measurements showed that the RF bias can improve the radial uniformity and edge to centre electron density ratio.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available