An ion implanter. The ion implanter may include an ion source to generate an ion beam; and a linear accelerator, to transport and accelerate the ion beam, the linear accelerator comprising a plurality of acceleration stages. A given acceleration stage of the plurality of acceleration stages may include an RF power supply, arranged to output an RF signal, and a drift tube assembly, arranged to transmit the ion beam, and coupled to the RF power supply. The given stage may also include a resonator, the resonator comprising a resonator enclosure, having a tapered shape, wherein the resonator enclosure has a first width in a middle location, a second width at a first end and a third width at a second end, wherein the first width is greater than the second width and greater than the third width.

A filament alignment device for accommodating a PFG including a support plate, an insulator on the support plate, and a filament at an end portion of the insulator includes a main case having a first plate groove into which a first portion of the support plate is inserted and an open side surface, an auxiliary case for covering at least a first area of the open side surface of the main case and having a second plate groove into which a second portion of the support plate is inserted, a height adjuster including a height controller on an upper sidewall of the main case and a fixing hook provided on an end portion of the height controller and which the filament is hung, and a hinge for rotatably connecting a sidewall of the auxiliary case to a sidewall of the main case.