Liq. helium pump with superconductive electromagnetic drive - capable of working in magnetic fields of several tesla density giving constant differential pressure and constant flow

摘要

A liq. helium pump with a superconductive electromagnetic drive has a fixed superconductive exciter coil joined to the body of the pump and a mobile element of superconductive construction across the field of the exciter coil and fixed to the piston of the pump. The superconducting electromagnetic drive consists of an electromagnet with annular air-gap placed in the pump body and enclosed on all sides by a superconductive magnetic screen. The electromagnet has a ferromagnetic core which is connected at one front part to a ferromagnetic yoke surrounding the core, which forms with the core an annular air-gap in the region of the other front part. The core carries a superconductive exciter winding. A superconductive plunger coil is placed in the annular air-gap, coaxially with the superconductive exciter winding, on a coil holder displaceable in the direction of the axis of the electromagnet with annular air-gap. The superconductive drive device is free from construction elements lying across the pump body, and the pump can work without perturbations even in strong external magnetic fields of a density of several teslas. It gives a constant differential press. between the inlet and outlet of the pump and consequently a constant quantity at a suitable flow rate.