| 摘要 |
PURPOSE:To improve the electric power efficiency and reduce the maintenance by performing the ionization and excitation of gas with the microwave electric power, feeding electrons having the energy with the high sticking probability from a hot cathode to collide with the generated particles in an excitation state, and generating negative ions. CONSTITUTION:The microwave electric power generated by an oscillator 1 is fed through a microwave transmitting window 6 via a dummy load 2, a directional coupler 3, a stub tuner 4, and a wave guide 5, the ionization and excitation of gas is performed to generate plasma by utilizing the relative action with the magnetic field generated by a permanent magnet 8 provided on a vacuum container 9. Electrons emitted from a hot cathode 13 and having the energy with the high sticking probability collide with the particles flowing out from a plasma chamber 7 in an excitation state to generate negative ions. Therefore, the bias voltage in relation to the surrounding space potential is applied to a hot cathode 13, permanent magnets 10 are arranged around a negative ion generating chamber 14 so as to form the multi-cusp magnetic field, thus a larger quantity of negative ions can be extracted. Accordingly, the electric power efficiency is improved, and the maintenance can be reduced.
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