Development of electron swarms in SF6

The electron swarm behaviour in SF 6 is calculated and analysed for a wide range of E/N values from 71 to 5656 Td by both a Boltzmann equation method and a Monte Carlo simulation, using a set of electron collision cross sections determined by the authors. The Monte Carlo result shows clearly that the difficulty in deducing the electron energy distribution increases as the E/N values decrease due to a large electron attachment probability, while the result of the Boltzmann equation analysis shows that the set of cross sections determined by the authors is again fully valid for E/N>707 Td, since the effective ionisation coefficient agrees with measurements at very high E/N. The swarm parameters for important experimental conditions are deduced and the validity of the usual two-term method is discussed in detail.