Basic Processes of Gaseous Electronics

The Measurement of Electron Drift Velocities

“…Lucas (1964) has derived an expression for the spatial electron distribution in an avalanche when ionization occurs and this result (equation (2) of Lucas 1964) can be used in an analysis of the current-frequency curves similar to that carried out by Lowke (1962). Assuming that dWjD ~ 1 the expression for W' then becomes…”

“…When E /p is sufficiently small so that ionization in the gas does not contribute significantly to the total measured current, Lowke (1962) has shown that the value W' of the drift velocity calculated using equation (1) is related to the true drift velocity W by the equation…”

“…Several methods (Loeb 1955;Breare and von Engel 1964;Raether 1964) have been devised to measure the drift velocity W of electrons moving under the influence of an electric field E through a gas at pressure p. The most accurate method is that of Bradbury and Nielsen (1936) (see also Lowke 1963), but for reasons discussed below this technique has been limited to low values of E/p. We have found that the useful range of this method can be greatly extended by some modification to the conventional form of the apparatus.…”

“…This type of shutter has been used for the measurement of positive ion mobilities (Loeb 1955). With this arrangement, maximum transmission through each shutter occurs when the a.c. voltage is a maximum and in the same sense as the applied d.c. field.…”

Simple template-based method to produce bradbury-nielsen gates

“…BNGs were first proposed by Loeb [2] and demonstrated by Cravath [3] in 1929 as electron filters. They were further developed by Bradbury and Nielsen in 1936, where the name of the device originates [4].…”