Experimental Investigations of Closed-Loop MPD Power Generation

Modifications and previously unreported results of an investigation of plasma properties and generator performance in a closed-loop facility employing caesium-seeded helium are described. The facility and generator have been modified to allow operation at channel inlet conditions of 1 atm static pressure. 1700°K static temperatur, and 0.5 Mach number. The magnetic induction is 2 tesla. The 0.02 x 0.03 x 0.45 m3 generator channel incorporates 47 pairs of electrodes which can be connected in continuous, segmented, or Hall configuration. Provisions were made to avoid electrode shorting and reduce Hall field shorting. Caesium is metered as a liquid by positive displacement, evaporated, and injected as a vapour through a multi-orifice manifold. Injection rate is electronically controllable over a seed-ratio range from 0.001 to 0.03. Consideration has been given to the measurement of non-equilibrium plasma properties and performance due to magnetically induced ionization. Theoretical calculations are presented for non-equilibrium conductivity and generator performance. A maximum electric conductivity increase factor of 3.3 within the channel for the prescribed conditions is predicted. Prohibitive losses are predicted for the Hall configuration due to shorts to ground in upstream and downstream transition sections. Facility modification and reassembly are completed. (author)