ION SOURCE FOR COMBINED USE BY POSITIVE AND NEGATIVE POLARITY

摘要

PURPOSE:To improve working speed and analytical sensibility through making it possible to take out the positive and negative ion beam from the same source by forming the material of ion emitter through mixing and sintering of a mate rial having high work function and that having low work function. CONSTITUTION:A sleeve 2 including a porous emitter 6 provided therein, formed through mixing and sintering of the material having high work function such as tungsten, etc. and the material having low work function such as lanthanum boride, etc. is attached to the top end of an ion source raw material storage 1, an electron ray heating filament 5 is provided around its circumference, furthermore a wehnelt electrode 4 a control electrode 7 and a take out electrode 8 for controlling the electron beam, are provided to form the surface ionized type ion source. When the potential of the emitter 6 is positive to the take out electrode 8, positive ions are taken out and when the potential of the emitter 6 is negative to the take out electrode 8, negative ions are taken out. Thereby, an ion beam of the element having different chemical characteristic can be easily taken out and high efficiency of working or analysis can be established.