PUMPING UNIT FOR PUMPING LIGHT GASES, AND USE OF THE PUMPING UNIT

摘要

A pumping unit for pumping light gases has a first dry vacuum pump (12) which is connected to the chamber (10) to be evacuated and a second dry vacuum pump (14) which is connected to the first dry vacuum pump (12). The pumping unit likewise has further dry vacuum pumps which are arranged in parallel or in series with respect to said pumps. According to the invention, they are dry vacuum pumps in order to avoid contamination of the light gases on account of the provision of oil-sealed pumps or on account of the provision of purge gas, which dry vacuum pumps are sealed hermetically with respect to the surroundings, with the result that low process pressures can be generated in the chamber (10) to be evacuated.