Effects of large concentrations of helium on the mechanical properties of neutron-irradiated stainless steel

Several concepts of a controlled fusion reactor utilize a beam of neutral atoms with kinetic energy in the range of 200 keV. Presently existing beams in the range of 10 to 20 keV are converted to neutral beams with an efficiency of like 85 percent via the electron capture mechanism. At 200 keV this conversion efficiency drops to like 20 percent because of the rapidly decreasing electron capture cross-section with increasing beam energy. This note suggests recycling the charged beam back through the neutralizer cell while continually removing the neutralized particles thus improving the overall efficiency. In principal, this recycling can be accomplished by a properly designed magnetic guide field