Performance improvement due to additional collectors in a secondary electron direct energy converter simulator

•Performance improvement of secondary electron direct energy converter was studied.•Additional electron collectors succeeded in enhancing secondary electron emission.•Blocking plates succeeded in suppressing scattered protons.•Recovered power increased by 75% compared with the conventional structure. The structure of secondary electron (SE) direct energy converter (SEDEC), which was proposed as an additional energy recovery device settled in the downstream of traveling wave direct energy converter for D-3He fusion, was investigated to improve its performance. Additional electron collectors (A-ECs) were settled near foil electrodes for quick collection of SEs. As the location of the A-ECs was close to the proton beam, scattered protons were incident on the A-ECs, leading to a decrease in the net electron current. Blocking plates were used to suppress incident of protons. The net electron current recovered and overcame the level measured in the conventional structure. The recovered power increased by 75%.