A method for measuring the evaporation rate of in the vacuum vaporised substances, measurement apparatus to its carry out and use of this method

摘要

1,194,943. Electron beam tubes; ionization manometers. BATTELLE DEVELOPMENT CORP. 19 April, 1968 [21 April, 1967; 26 March, 1968], No. 18583/68. Heading H1D. [Also in Divisions G1 and G3] The rate of evaporation of a substance 9 emitted in the form of a jet 8 of vapour is measured by scanning an electron beam 5 through the jet, and collecting the ionization products resulting from collisions during scanning by electrode 4, the ionization current being composed of a continuous component due to collisions with residual gas atoms and a periodic component due to the collisions with the particles of the vapour jet, the amplitude of the latter component representing the numerical density of the vapour jet particles. The scanning action may be electrostatic or magnetic giving a rectilinear trace or a circular trace (Fig. 4, not shown). The waveform applied to the scanning plates from oscillator 19 may be sinusoidal, sawtooth, square wave or stepped. When the scan is circular, the electron collector 3 and the collision particle collector are of annular configuration. The collision products may be electrons or ions resulting from elastic or inelastic collisions respectively. The rate of evaporation of several vapour jets may be measured using one scanning electron beam.