ANGULAR-DISTRIBUTION AND ENERGY SPREAD OF A LITHIUM LIQUID-METAL ION-SOURCE

For a lithium liquid metal ion source (LMIS) an especially high angular intensity acid a low energy broadening is expected because of the low mass of lithium. For a Li LMIS the axial angular intensity and the FWHM of the energy distribution have been measured. The results have been compared with the theoretical predictions and with experimental results for gallium, the metal most widely used in LMIS. A correlation between angular intensity and the energy broadening is found. The Li LMIS has a high angular intensity, especially at low currents, compared to the Ga LMIS. The energy spread in the low-current range is 25% lower than for the Ga LMIS. With increasing emission current the rise of the angular intensity as well as the energy broadening is smaller than for the gallium source.