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Proceedings Paper

Laser photodetachment measurements of the negative ion density in an oxygen currentless plasma
Author(s): Tsviatko K. Popov; Sanka V. Gateva
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Paper Abstract

Laser photodetachment measurements of the negative ion density in an oxygen currentless plasma are reported. For this experiments a DC gas discharge tube with a coaxial nickel sectional cathode (diameter 5.10-2 m) and a grid anode (diameter 2.10-2 m and length 0.2 m) is used. The measurements are made in pure oxygen at gas pressure 109 Pa and discharge current 40 - 80 mA. Inside the anode region the reduced electrical field E/Ng is near zero (Ng is the gas density). The currentless plasma is formed by plasma particles moving from the negative glow into the cavity inside the anode. The negative charged particles dominantly are negative ions with Maxwellian energy distribution. The negative ion density is measured on the axis in the center of the discharge tube by measurement of the relative absorption of the laser power. A 5 mW 785 nm diode laser is used for the measurements. The obtained values of the oxygen negative ion density at gas pressure 109 Pa and 80 mA are approximately 10-13 cm-3 and are in good agreement with the values obtained by second derivative Langmuir probe measurements.

Paper Details

Date Published: 9 April 2001
PDF: 5 pages
Proc. SPIE 4397, 11th International School on Quantum Electronics: Laser Physics and Applications, (9 April 2001); doi: 10.1117/12.425134
Show Author Affiliations
Tsviatko K. Popov, Institute of Electronics and Univ. of Sofia (Bulgaria)
Sanka V. Gateva, Institute of Electronics (Bulgaria)


Published in SPIE Proceedings Vol. 4397:
11th International School on Quantum Electronics: Laser Physics and Applications
Peter A. Atanasov; Stefka Cartaleva, Editor(s)

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