Process for generating a working gas stream

The invention is based on the object of providing a process by means of which a working gas stream can be generated, which can be controlled as accurately as possible with respect to temperature and flow rate. In the process according to the invention, the temperature and the flow rate of the working gas stream (3) are controlled by means of the flow rates of two partial gas streams (1, 2), the temperature of the first partial gas stream (1) lying below and the temperature of the second partial gas stream (2) lying above the desired temperature of the working gas stream (3). In this case, temperature and flow rate of the working gas stream (3) are measured and at least the measured value of the temperature is detected by means of a measuring and control unit (4), which controls the flow rates of the individual partial gas streams via two flow control units (5, 6), one of which respectively each controls the flow rate of one partial gas stream (1, 2), as a function of the differences between the desired values and actual values of the temperature of the working gas stream (3). The process according to the invention is used for generating a cold working gas stream for cooling in the production of optical waveguides.