High precision two photon spectroscopy in hydrogen isotopes for the measurement of the electric field in plasmas generated in hollow cathode discharges.

In this thesis, the intensity of the local electric field in the cathode region of a hollow cathode discharge operated in hydrogen was measured, in a wide range of pressures and currents to study the influence of the diameter (10 and 15 mm) and material of the cathode used (stainless steel and tungsten). The method is based on the Stark effect of the level n=2, via the absorption of two 243 nm photons, circularly polarized in opposite directions, to eliminate the Doppler effect. When the atom is in the 2S state, it photo-ionizes, modifying the impedance of the plasma, which can be detected as the voltage drop on a resistor (optogalvanic spectroscopy). The local electric field is determined by comparing the separation of the Stark components with the theoretical values. [ABSTRACT FROM AUTHOR]