Improved ion source for use with oxygen

When Kaufman ion sources are used with pure oxygen at high discharge powers, their operational lifetime is limited to minutes. The lifetime of the source can be significantly increased by using thoria-coated filaments for the cathodes. In addition, the lifetime can be increased further by coating the anode with a conductive oxide such as Ir02. This coating is deposited by sputter deposition. With these improvements the operational lifetime can be increased by a factor of 100. © 1988, American Vacuum Society. All rights reserved.