Laser photodetachment measurements of the negative ion density in an oxygen currentless plasma

Tsviatko K. Popov; Sanka V. Gateva

doi:10.1117/12.425134

9 April 2001 Laser photodetachment measurements of the negative ion density in an oxygen currentless plasma

Tsviatko K. Popov, Sanka V. Gateva

Proceedings Volume 4397, 11th International School on Quantum Electronics: Laser Physics and Applications; (2001) https://doi.org/10.1117/12.425134
Event: 11th International School on Quantum Electronics: Laser Physics and Applications, 2000, Varna, Bulgaria

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/N_g is near zero (N_g 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.

Citation Download Citation

Tsviatko K. Popov and Sanka V. Gateva "Laser photodetachment measurements of the negative ion density in an oxygen currentless plasma", Proc. SPIE 4397, 11th International School on Quantum Electronics: Laser Physics and Applications, (9 April 2001); https://doi.org/10.1117/12.425134

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