Measurements of partial outgassing rates

To investigate the surface composition and outgassing rates of a series of samples, the size of these should be small and the measuring time variable. Because the species of desorbed gases vary with dependence on time and temperature, the outgassing measurements using total pressure gauges include some errors caused by the conductance and the gas correction factor for the gauges. To reduce these errors we developed an outgassing measurement system on the basis of a modified throughput method with quadrupole mass spectrometers. By this method it is possible to measure partial outgassing rates. The change of major gas components is discussed. Some examples of the outgassing behaviour of stainless steel, nickel and chromium coated brass are given.