pump for pumping liquid molten metal

The specific character of employing the designed pump in high-power plasma X-ray and EUV sources in many respects specified the features of its design. First, the operating temperature of the pumped liquids should be no less than 350°C. Second, the liquid metal, e.g., tin, circulating through the vacuum volume evacuated to a pressure of 10–4 mbar, should be enclosed in the completely sealed contour. Third, the materials, of which assemblies and elements of the pump are made, including bearing mount assemblies, should be corrosion-resistant to the action of the pumped liquids. Fourth, the pump should develop a pressure sufficient for producing metal jets with a velocity of up to 15 m/s and a flow rate of up to 1 m3/h. Fifth, the design of the pump should be compact. At last, the liquid pressure pulsations at the pump output should be minimized.

The life tests of the pump showed that the ceramic bearings were the least wear-resistant element. Nevertheless, even if not the hardest ceramics was used, the operating life was ~200 h.

We hope that, when a VK-100 harder ceramics is used, the operating life of the pump will significantly increase. Now the pump with
other molten metals, in particular, liquid lithium, is being prepared for tests. For this purpose, some changes are brought into the pump design, and materials compatible with lithium are selected. We do not see limitations on applying the designed pump for pumping other liquid metals and alloys and aggressive high-temperature liquids with an operating temperature of up to 380°C.

The pump is successfully used in the high-power electric-discharge EUV source (λ = 13.5 nm), and, by means of it, liquid tin is pumped over the closed contour, and high-speed (up to 15 m/s) liquid tin jets used as electrodes with an unbounded service life are produced. The design of the magnetic coupling of the pump and the design of the pump itself were patented.