Mass Filtering Function of Magnetic Boundaries in Multi‐Cusp Ion Source

In a multi‐cusp ion source, magnetic boundaries, together with the difference between plasma potential and plasma chamber potential, functioned as a mass filter which filters out heavier ions in multi‐component plasmas. This method was applied to mixed inert gas plasmas and hydrogen plasmas and found to be very effective for general purposes which require to decrease unwanted heavier ions. Using this method to the ion source of iG4, target boron current above 80 mA and proton current above 120 mA were obtained.