Broad beam high average current metal ion source

For industrial application in material surface modification it is necessary to obtain higher average beam current for metal ion implantation. Two new versions of MEVVA ion source, MEVVA-II and MEVVA-IIA, in which the size of the extraction area is expanded to 60 mm in diameter have been developed, based on MEVVA-I being constructed early. The sources are operated in pulsed mode with a maximum beam duty cycle of 6%. A time average beam current of up to 10–30 mA has been extracted from a range of different cathode materials, such as C, Mg, Al, Ti, V, Cr, Fe, Ni, Cu, Zn, Y, Zr, Mo, Nb, Sn, Ta, W, and Pb. In the MEVVA-IIA, particularly, a movable cathode is used for compensating the consumption of the cathode material during the source operation, so that the running time may be extended, for example, it has been operated stably more than 16 h with a 10 mA beam current with a Ti cathode. In this paper, we will describe the source and some preliminary results.