Several techniques for suppressing the electrons before they form part of the extracted beam have been studied in a small multicusp H⁻ source. It is found that some schemes reduce both the electron and the H⁻ output currents. Other approaches, such as the installation of a collar at the extraction aperture, the addition of xenon or cesium to the hydrogen discharge, or the reduction of the source plasma potential, not only can reduce the electron current substantially, but bring about an enhancement in the extracted H⁻ current.

Compact neutron generators can provide a high flux of neutrons with energies ranging from thermal (0.025 eV) to 14 MeV. The application of the deuterium-deuterium, D-¹⁰B, and D-⁷Li nuclear reactions and new advancements in high-flux neutron generator technology along with the commercial availability of high-voltage direct current power supplies enables the production of high-flux 2.45-, 6-, 10-, and 13-MeV neutrons. The high-energy neutrons or the moderated epithermal neutrons from the new compact neutron generator can greatly advance cancer therapy, radioisotope production, neutron yield measurement, special nuclear materials detection, and neutron transmutation doping of silicon.

A system to determine the density and temperature of ground‐state hydrogen atoms in a hydrogen plasma by measurement of the absorption of Lyman‐beta or Lyman‐gamma radiation is described. The Lyman‐series radiation is generated by resonant four‐wave sum‐frequency mixing in mercury vapor. A wide range of hydrogen atom densities can be measured by employing these two transitions. A sample measurement on a H⁻ ion‐source discharge is presented. Extensions to Lyman‐alpha and other vacuum‐ultraviolet wavelengths are discussed.

A small microwave ion source has been fabricated from a quartz tube with one end enclosed by a two-grid accelerator. The source is also enclosed by a cavity operated at a frequency of 2.45 GHz. Microwave power as high as 500 W can be coupled to the source plasma. The source has been operated with different geometries and for various gases in a cw mode. For hydrogen, ion current density of 200 mA/cm2 with atomic species concentration as high as 80% has been extracted from the source. It has been demonstrated that low-energy oxygen ion beams can also be extracted from the source. Beam-energy spread has been measured to be less than 1 eV.