ELECTROMAGNETIC PUMP TECHNOLOGY FOR SPACE FLIGHT APPLICATIONS

摘要

Electromagnetic (EM) pumps have been used in every space reactor power system flown in space since April 3,1965 when the SNAP-10A Flight System (FS-4) was launched on an Atlas-Agena launch vehicle into a 700 NM sun synchronous orbit. Since that time, the Russians have launched more that 30 satellites powered by nuclear reactor heat sources. All of these space power systems have used a liquid metal coolant to transport the reactor's thermal energy to an external heat exchanger. Thermoelectric- and thermionic-powered DC conduction EM pumps were used in these missions. As a class of EM pumps, the DC conduction pump, known as a Faraday pump, requires high current densities and low voltage drop to operate efficiently. Thermoelectric and thermionic power sources provide these electrical bus qualities with a minimum mass impact and have been integrated into the space reactor power system EM pump assembly in various forms using the DC conduction pump. These include the thermoelectric-powered EM pump (or TEM pump) and the thermionic EM pump (or TIEM pump). Most of these applications were for relatively low power applications (i.e., <100 kWt) heat source. As the size of the space reactor thermal power level increases, the need for higher hydraulic power levels from these pumps has brought into consideration a second class of electromagnetic pump. Known as induction machines, these EM pumps use a traveling magnetic field to induce a voltage across the liquid metal fluid in the pump throat, which causes a current path to form at right angles to the impressed magnetic field and a Lorenz force acts on the fluid based again on the Faraday principle. Hundreds of these EM pumps in various forms and sizes have been built and operated in terrestrial applications over the past 40 years. They generally employ a three-phase AC, high voltage power supply that provides moderate current levels per phase depending on the size of the pump and its application. They have provided highly reliable service for the pumping of high temperature molten metals in commercial applications. Previous studies (SP-100 Program, MMW, and others) have examined the induction EM pump design for higher power level space power system applications. The paper will briefly review the general principles and past applications of EM pump technology applied to space power applications.