The diffusion pump compresses the gas through the transfer of momentum. The electric furnace heats the diffusion pump oil in the pump body. After the diffusion pump oil vaporizes, it is pressurized in the internal injection tower. The high pressure in the injection tower pushes the pump oil molecules to eject from the annular nozzle. The oil molecules The gas molecules entering the pump body are captured and forced to move diagonally downward. The oil molecules condense on the cooled pump wall. After several consecutive cycles, the gas is compressed and transported to the exhaust port to be pumped away by the backing pump