The power carried out through the ends of a mirror fusion reactor by escaping plasma can be converted directly into electricity by a plasma direct converter. Test results from three plasma direct converters are described. The first two tests were performed with a steady-state power density up to 70 W/cm2 to simulate the predicted conditions on a reactor (∼100 W/cm2). A single-stage unit and a two-stage unit of the venetian-blind type were tested up to 100 kV and 6 kW for a total time of ∼80 h. In scaling up in energy from previous experiments, the new effects that became important were the ionization of background gas and the release of secondary electrons at surfaces. In the third test, a single-stage unit was mounted on the end wall of the Tandem Mirror Experiment (TMX) device where it intercepted some of the end-loss plasma. Of the 138 W incident on the direct converter, 79 W were recovered and 12 W were used to power the suppressor grid. The net efficiency was therefore 48%; this was in good agreement with predictions for a single-stage unit and the TMX plasma parameters. These test results lend confidence to our direct-converter designs for fusion reactors. The remaining area of concern includes the general problem imposed by high-voltage breakdown in a large direct converter with many joules of stored energy.