Ionization, electron attachment, and drift in CHF3

Using a pulsed Townsend technique, we have measured the effective ionization coefficient and the electron drift velocities in CHF3. 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 Td, the electron attachment coefficients are practically constant, and are compatible to within about +/-70% with previously measured values at thecal energies and above. [S1063-651X(99)08410-X].