Negative ion source on the secondary emission electrons

Summary form only given. The source of negative ions has been elaborated on the basis of the low pressure beam-plasma discharge. Negative ions are generated by electron-atom interaction (A+e/spl rarr/A/sup -/) and extracted across the magnetic field. The high concentration of low energetic electrons is reached with the help of secondary electron-electron emission by interaction of the primary stationary electron beam with target made of materials with high secondary emission rate. Secondary emission electrons is accumulating in electromagnetic trap like Penning cell with plug profile magnetic field. We have discovered that there are two operating conditions of the negative ion source that depend upon the correlation of discharge characteristics.