Instability in low energy beams extracted from BF3 plasma

摘要

Ion beam instabilities on a wide ribbon beam which cross-section is 150 cm × 10 cm are discussed. At low energy conditions, we detected two kinds of instabilities on the ion beam extracted from BF plasmas. One kind of the instabilities is that onset of the instability is dependent on the extraction current from the ion source. This instability occurred when the extraction current exceeded 300 – 350 mA at the energy of 15keV. Another is that the onset is dependent on the BF beam current. The BF beam current became unstable when it exceeded about 20 µA/cm at 15keV. Energy dependence of these instabilities is also discussed.