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Side-Extraction-Type Secondary Emission Electron Gun Using Wire Ion Plasma Source

A secondary emission electron gun applicable for gas treatment was designed, fabricated and tested. The gun is set beside an ion source, which is called a wire ion plasma source (WIPS). Ions extracted from WIPS are accelerated toward the cathode surface, which is set oblique to the ion loci. Secondary electrons emitted from this cathode surface by the collision of ions are then accelerated toward the electron window and form a very wide electron beam. The electron window is set orthogonal to the ion extraction window and has earth potential. In order to inject the electron beam perpendicular to the electron window, the ion and electron trajectories were numerically simulated for several conditions. A wide electron-beam current distribution was observed inside the gas treatment chamber when a honeycomb board and an Al film were placed at the electron window. The electron-beam current density of 6.4 mA/cm2 measured at the cathode voltage of 80 kV possesses sufficient energy to irradiate gaseous pollutants such as NOx.