Unipolar electrostatic quadrupole lens and switching methods for charged beam transport

A linear acceleration system comprising:

• one or more accelerating stages along an axis of the system;
• and
• a first electrostatic quadrupole lens in series with the one or more accelerating stages that focuses an ion beam in a direction transverse to the axis, wherein the first electrostatic quadrupole lens comprises:
• a switching circuit controllably connected to ground and a first voltage potential;
• a first pair of electrodes located opposite each other, connected to the switching circuit;
• and
• a second pair of electrodes located opposite each other, wherein the first pair of electrodes and the second pair of electrodes are equally spaced about a center point, the second pair of electrodes biased to a second voltage potential.

A method of operating an ion implantation system, comprising:

• extracting an ion beam from an ion source;
• determining whether a desired ion beam energy is greater than a first threshold;
• and
• configuring a quadrupole lens along a beam path of the ion beam in one of a bipolar configuration or a unipolar configuration based on the determination.