A new type of effusion cell has been developed for thermal evaporation of materials up to 1300 °C under ultrahigh vacuum conditions. The evaporation rate, measured by a quadrupole mass spectrometer, is controlled by moving a mechanical shutter connected to the cell and not by varying the temperature. An electronic feedback circuit positions the shutter and allows computer programming of arbitrary profiles. Compared to common thermal control, any desired evaporation rate can be stabilized faster, for example, in less than 2 s.

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