| 摘要 |
<p>A magnetic deflection system (34) for scanning an ion beam over a selected surface comprising: a magnetic structure (50) having poles with respective scanning coils (58) and respective pole faces (52) that define therebetween a gap (54) through which the ion beam passes (13); a primary current source coupled to the scanning coils (58) adapted to apply to the scanning coils (58) an excitation current to generate a substantially unipolar oscillatory magnetic field (56) in the gap (54) that alternates in polarity as a function of time to cause scanning of the ion beam (13), the substantially unipolar magnetic field (56) having a magnitude sufficiently greater than zero to prevent the transverse cross section of the ion beam (13) from substantially fluctuating in size while the ion beam (13) is being scanned across the selected surface.</p> |
