High-density and low electron temperature direct current reflex plasma source

A new type of direct current, high-density, and low electron temperature reflex plasma source, obtained as a hybrid between a modified hollow-cathode discharge and a Penning ionization gauge discharge is presented. The plasma source was tested in argon, nitrogen, and oxygen over a range pressure of 1.0-10(-3) mbar, discharge currents 20-200 mA, and magnetic field 0-120 Gauss. Both external parameters, such as breakdown potential and the discharge voltage-current characteristic, and its internal parameters, like the electron energy distribution function, electron and ion densities, and electron temperature, were measured. Due to the enhanced hollow-cathode effect by the magnetic trapping of electrons, the density of the bulk plasma is as high as 10(18) m(-3), and the electron temperature is as low as a few tenths of electron volts. The plasma density scales with the dissipated power. Another important feature of this reflex plasma source is its high degree of uniformity, while the discharge bulk region is free of an electric field. (C) 2004 American Institute of Physics.

Is the flow tube reactor with NO2 titration a reliable absolute source for atomic hydrogen?

The H+NO2 titration scheme for the determination of atomic hydrogen densities within a microwave excited flow tube reactor has been investigated by laser-induced fluorescence spectroscopy in the vacuum UV. Absolute hydrogen densities are determined on the basis of calibration by Rayleigh scattering from argon. The measurement is performed at a gas mixture containing 0.5% of D2 added to the main gas H2. The ground state density of the hydrogen atoms generated in the flow tube reactor was inferred from the fluorescence radiation of the spectrally shifted optically thin D-Lyman-a transition.