J de Urquijo

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  • J de Urquijo, E Basurto, +4 authors R D White
  • The Journal of chemical physics
  • 2014
The drift velocity of electrons in mixtures of gaseous water and helium is measured over the range of reduced electric fields 0.1-300 Td using a pulsed-Townsend technique. Admixtures of 1% and 2% water to helium are found to produce negative differential conductivity (NDC), despite NDC being absent from the pure gases. The measured drift velocities are used(More)
The ion mobility or drift velocity data important for modeling glow discharges in rare gas mixtures are not generally available, nor are the ion-neutral scattering cross sections needed to calculate these data. In this paper we propose a set of cross sections for Xe+ and Ne+ collisions with Xe and Ne atoms. Ion mobilities at 300 K calculated using this(More)
This paper reports a drift-tube-mass-spectrometer measurement of the relative abundances of N+ and N+2 in pure nitrogen, over a ratio of electric field to gas density, E/N, from 800 to 7200 Td [1 townsend (Td)=10(-17) V cm(2)]. A proposed charge transfer dissociation scheme between the above two ions and N2 allowed us to obtain spatial rate coefficients for(More)
Measurements of electron drift velocities were performed in pure Xe and He and in a number of mixtures ranging up to 70% of Xe. The data were obtained by using a pulsed Townsend technique over the density-normalized electric field strength E/N between 1 and 100 Td . Even for pure gases there are no data in the entire range covered here, and these data(More)
This paper reports on the mass-analyzed measurement of the drift velocity of the positive SF6 daughter ions, SF+x (x=1-3,5) in the mixture of SF6 with N2 for SF6 concentrations of 10% and 50%. A double mass spectrometer-drift tube was used for these measurements. The density-normalized electric field intensity E/N, was varied from 30 to 360 Td (1 Td=10(-17)(More)
Using a pulsed Townsend technique, we have measured the effective ionization coefficient and the electron drift velocities in CHF(3). The density-normalized electric field intensity E/N ranged from 4 to 250 townsends (Td) (1 Td=10(-17) V cm(2)). The E/N value at which the effective ionization coefficient becomes zero was estimated to be 66 Td. For E/N<20(More)
The measurement of the mobility of SF-6 in the mixtures SF6 -Ar and SF6 -Xe is reported over the density-reduced electric field strength E/N 1-180 Td (1 Townsend = 10(-17) V cm(2)), from a time-resolved pulsed Townsend technique. Simultaneously, the mobility of SF-6 in the same binary mixtures has been calculated from a set of collision cross sections for(More)
This paper deals with the measurement of the mobility of negative ions in the mixtures of SF6 with CF4 and the CH4-Ar (50:50) binary mixture with SF6 contents up to 50%. The pulsed Townsend technique was used to observe the integrated ionic avalanches over a range of the density-reduced electric field E/N for which ionization is either negligible or absent,(More)
A simple, easy to build electronic circuit consisting of an amplifying chain followed by a state-variable bandpass filter has been used to measure the thermal noise produced by a resistor. Using Johnson’s theory for thermal noise, Boltzmann’s constant could be derived with an accuracy of 1.4% of its accepted value. This simple instrument can be very useful(More)
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