A very extensive compilation of Stark widths and shifts for more than 125 Ar II visible spectral lines is presented in this work. These atomic parameters have been measured in a pulsed discharge lamp by using different mixtures of pure argon or argon and helium. The electron density, which typically ranges from 0.2 to 2.0 × 10 23 m −3 has been determined interferometrically and, in the case of pure argon plasmas, also spectroscopically from H α -Stark broadening. The Ar II excitation temperature (15 000-31 000 K) has been determined by Boltzmann-plot techniques from the intensity of Ar II lines. A detailed description of all the relevant points in this kind of measurement is given. Comparisons with most of the data published about this topic for Ar II are also included.

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We present, in this work, Doppler-free two-photon optogalvanic spectroscopy as a tool to measure the electric field strength in the cathode fall region of a hollow cathode discharge via the Stark splitting of the 2S level of atomic deuterium. The strong electric field strength (1 to 4 kV cm −1 ) present in the hollow cathode is determined for various discharge conditions (currents from 50 to 200 mA and pressures from 400 to 1350 Pa), which allows investigation of the corresponding variations of the cathode fall and its changes with discharge operation time.

In this work, Doppler-free two photon optogalvanic spectroscopy is used to measure the electric field strength in the cathode fall region of a hollow cathode discharge, operated in pure hydrogen, via the Stark splitting of the 2S level of atomic hydrogen. The cathode fall characteristics are analysed for various pressures and in a wide range of discharge currents. Tungsten is used as the cathode material, because it allows for reliable measurements in a fairly wide range of discharge conditions and because of its minimal sputtering. Two cathode diameters (10 mm and 15 mm) are used to study the dependence of the cathode fall on discharge geometry. The measurements reveal that the cathode fall characteristics are quite independent on the cathode diameter for equal cathode current density; hence the measurements can be used to test one dimensional modelling of the cathode fall region for low pressure hydrogen discharges using e.g. plane parallel electrodes.