UNIVERSITY OF BUCHAREST
FACULTY OF PHYSICS

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Conference: Bucharest University Faculty of Physics 2002 Meeting


Section: Optics, Spectroscopy, Plasma and Lasers


Title:
Experimental setup for investigation of ionic species in a RF generated remote plasma


Authors:
D. Crintea, B. Mitu, S. Vizireanu, E. Raiciu, G. Dinescu


Affiliation:
D. Crintea, B. Mitu, S. Vizireanu, E. Raiciu, G. Dinescu

Low Temperature Plasma Physics Department

National Institute of Lasers, Plasma and Radiation Physics,

POB MG-36, Magurele, Bucharest, Romania


E-mail


Keywords:


Abstract:
The plasma content of ions is an important parameter for understanding the fundamental processes. Also, the ions play a key role in plasma applications. In the case of remote plasmas these species are hardly seen by emission spectroscopy, the high energy of their excited levels preventing the excitation by the electronic collisions. Therefore, other techniques have to be applied to investigate the ionic content of this plasma type. Mass spectrometry can be useful to detect the plasma ions, but the recombination of ions in their way from plasma to the detector strongly affects the results. In this contribution we present an experimental set-up in which the recombination is minimized by mounting the plasma source directly on the mass spectrometer. The experimental set-up consists of a plasma source, the transport section and the mass spectrometer. The plasma source is formed from a capacitively coupled RF discharge, operated at a pressure in the range 1-10 mbar. A nozzle connects the discharge to a vacuumed chamber where plasma species are transported at an intermediate pressure of 10-2 – 10-1 mbar. Finally, the species are transmitted in the measuring chamber (pressure 10-7 mbar-10-6 mbar) where the mass spectrometer is mounted, through a low diameter (~ 100 m) pinhole. The plasma source, the nozzle, the sampling pinhole and the mass spectrometer detector are placed on the same line, the recombination and the losses to wall being thus minimized. In addition, the device has a side window allowing optical emission spectroscopy investigation of neutrals present in the plasma expansion.