Temperature and velocity measurements of argon ions by resonance fluorescence with a single mode Ar-ion-laser

The spatial temperature distribution of the argon ions in front of the anode of a stationary hollow cathode arc was measured from the Doppler-width of the ArII-line at 488.0 nm. The radial velocities of the ions were derived from the shift of the line center. The line profiles were observed by resonance fluorescence scattering using an Ar+-laser operating at lambda 0=488.0 nm. The frequency of the single-mode laser was selected by an intracavity etalon. By tilting the etalon the laser was tuned over the gain profile. The typical ion temperatures in front of the anode are about 0.3 eV and slightly increase towards the arc column. In the anode region a strong radial ion velocity of about 1 km s-1 was detected.