Satoshi Nakamoto

Enhanced Energy Recovery in a Secondary Electron Direct Energy Converter through Reduction of the Magnetic Mirror Effect

Abstract With an aim to improve the total efficiency of a D-3He nuclear fusion direct energy conversion system, a secondary electron direct energy converter (SEDEC) is proposed. The incident high-energy protons in an SEDEC penetrate a large number of foil electrodes aligned in the direction of the proton beam, and emitted secondary electrons are recovered. The results of the initial experiments showed that most of the secondary electrons flowed into anteroposterior electrodes and did not arrive at the electron collector located alongside and perpendicular to the direction of the proton beam. A magnetic field was introduced to push the electrons toward the electron collector, but it was not effective for energy recovery. This technical note analyzes the trajectories of electrons in the presence of the magnetic field and proposes and examines a revised arrangement of permanent magnets. The arrangement of the magnets along one side of the proton beam greatly improved the energy recovery; however, the recovery level was lower than that without magnets.

Basic Characteristics of Secondary Electron Emission from Foil Electrodes for New Energy Recovery Scheme of High Energy Ions in an Advanced Fusion

The new energy recovery method using secondary electron emission has been studied in order to improve energy recovery from high energy protons of fusion products in D-3He nuclear fusion generation. The model experiments were performed by using the tandem electrostatic accelerator and the basic characteristics were investigated. According to our results, for penetration aluminum is better as a target material than copper, H+ is better than He2+, and higher energy beam is better which agree with numerical calculations. A qualitative characteristic of secondary electron emission dependence on beam energy was also obtained.

Examination on Plasma Production and Ion Heating for Electric Propulsion Using a Single Helical Antenna

A new structure of RF control of plasma for electric propulsion has been proposed. With excitation characteristics of a helical antenna and propagation characteristics of waves with rotating field, both plasma production and ion heating will be expected simultaneously by employing a single helical antenna. Basic experiments to examine the proposed structure have been performed, showing consistent results with expected scenario.