Linear ion source with closed drift and extended acceleration region.

Ion source with closed drift, which is caused by E x B field, and extended acceleration region is discussed. Though conventional circular-type closed drift ion source has advantages of high efficiency of gas ionization and low ion beam energy, there is a limitation in enlarging the beam size. Linear ion source with horse-track shape with 270 mm ceramic channel width is newly designed and tested. Inert gas (Ar) and reactive gas (O(2)) are discharged. Discharge is ignited with voltage of 90 V. Discharge current is proportional to discharge voltage and increases up to 16.3 A in argon and 15.6 A in oxygen at discharge voltage of 320 V. Extracted ion beam current is also proportional to discharge voltage and is saturated after 280 V for both gases. It is measured up to 0.78 mA/cm(2) in argon beam and 0.73 mA/cm(2) in oxygen beam at a distance of 100 mm from the ion source. Argon ion beam shows better space uniformity than oxygen across the beam extraction region.