An apparatus may include an ion source, arranged to generate an ion beam at a first ion energy. The apparatus may further include a DC accelerator column, disposed downstream of the ion source, and arranged to accelerate the ion beam to a second ion energy, the second ion energy being greater than the first ion energy. The apparatus may include a linear accelerator, disposed downstream of the DC accelerator column, the linear accelerator arranged to accelerate the ion beam to a third ion energy, greater than the second ion energy.