Untitled in english

Author(s)

Giuseppe Antonio Cirino

• Document type: Master's Dissertation
• Press: São Paulo.
• Institution: Universidade de São Paulo (USP). Escola Politécnica (EP/BC)
• Defense date: 1998-05-29

Examining board members

Patrick Bernard Verdonck; Homero Santiago Maciel; Gilberto Marrega Sandonato

• Advisor: Patrick Bernard Verdonck

Abstract

In this work we studied the characteristics of and the characterization by electrostatic probes. The plasma density, electron temperature, floating and plasma potentials for several cold plasmas were determined. Several probes were characterized: single probe with RF choke, single probe with RF choke and compensating electrode and double probe. The efficiency of the RF choke was characterized by coupling the probe to an oscilloscope and analyzing the AC-spectrum. This proved to be a simple and fast technique to verify the capability of the RF choke to reduce the RF field over the dark sheath of the probe. Argon plasmas were then characterized by three probes. The double probe proved to be the most precise. This probe and the single probe with RF choke and compensating electrode yielded compatible results for both electron temperature and plasma density. The single probe with RF choke and without compensating electrode overestimates the electron temperature and underestimates the plasma density. It is also the least reliable probe to determine the floating and plasma potentials. Finally, argon, oxygen and SF6 plasmas were characterized. (AU)