https://doi.org/10.1140/epjd/e2012-20676-5
Regular Article
Measurement of electron swarm coefficients in C2F4-Xe and evidence of Penning ionization in C2F4-Ar
1
Instituto de Ciencias Físicas, Universidad Nacional Autónoma de
México, P.O. Box
48-3, 62251
Cuernavaca, Mor., México
2
Departamentos de Energía y de Ciencias Básicas, Universidad
Autónoma Metropolitana-Azcapotzalco, Av. San Pablo 210, 02200
México, D.F.
a e-mail: jdu@fis.unam.mx
Received:
24
November
2011
Received in final form:
25
January
2012
Published online:
27
March
2012
We have measured the electron drift velocity, the effective ionization coefficient, and the longitudinal diffusion coefficient of electrons in the C2F4-Xe mixtures with 1% and 5% amount of C2F4. The electron drift velocity curves show a well defined region of negative differential drift velocity, and a similar effect is found for the density-normalized longitudinal diffusion coefficients at low E/N values. Previous findings of possible Penning ionization effects on the pulse shapes in the C2F4-Ar mixtures were not found in C2F4-Xe. This effect is further explored in this paper and fully supported by the simulation of avalanche development in the C2F4-Ar mixtures in which, apart from electron transport and effective ionization, the formation of metastable Ar∗ followed by ionization of C2F4 has been included. In most cases the comparison between simulations and measurements is very good, thereby giving further support to the original hypothesis.
Key words: Topical issue: Electron/Positron Collision. Guest editors: Michael Brunger, Anne Lafosse, Gaetana Laricchia, Paulo Limao-Vieira and Nigel Mason
© EDP Sciences, Società Italiana di Fisica and Springer-Verlag 2012