The Dependence of Measured Drift Velocity on Shutter Open Time in the Four Gauze Time-of-Flight Method

Abstract

Measurements of ion transit time by the four gauze time-of-f1ight method have been shown previously to have a small dependence on the shutter open time. This effect has been investigated for the case of Kr + ions in Kr and found to be due to the combined effects of diffusion and the injection of asymmetric ion pulses into the drift space. The cause of the asymmetry and procedures for checking for the presence of an error from this source are discussed. It is estimated that the error incurred can be reduced to within the experimental scatter of the measured mobility; that is, to less than ±0·15%.