Biased electrostatic deflector

A beamline assembly comprising:

• an accelerator component that selectively decelerates a ribbon shaped incoming ion beam;
• a tube focus component that further decelerates the ion beam and focuses the ion beam in a vertical direction;
• and
• an angular electrostatic filter that removes energy contaminants from the ion beam and directs the ion beam toward a target, wherein the angular electrostatic filter comprises:
• a top deflection plate extending from an entrance side to an exit side, wherein the top deflection plate is planar;
• a bottom deflection plate having a non-angled portion substantially parallel to the top deflection plate, extending from the entrance side toward the exit side and an angled portion extending from the non-angled portion to the exit side;
• an entrance electrode having an aperture that permits passage of the ion beam positioned at entrance side of the filter;
• an exit electrode positioned having an aperture that permits passage of the ion beam positioned at the exit side of the filter;
• a pair of edge electrodes extending from the entrance side to the exit side, substantially parallel to the top deflection plate and positioned midway between the top deflection plate and the bottom deflection plate;
• and
• an exit slit positioned downstream of the exit electrode that blocks energy contaminants and permits passage of ions having selected energies.

A method of removing energy contaminants form a ribbon shaped ion beam comprising:

• selecting an angle of deflection for a selected energy range for the ribbon shaped ion beam;
• applying an entrance focus field that focuses the ion beam in a vertical direction;
• applying an edge field that mitigates non-uniform fields near an end of a deflection field;
• and
• applying the deflection field according to the selected energy range at the selected angle of deflection, wherein applying the deflection field comprises applying a negative bias across a planar top deflection plate and a bottom deflection plate having an angled portion and a planar portion, wherein the ion beam travels between the top and bottom deflection plates, wherein the planar portion is parallel to the top deflection plates an is located at an entrance side of the deflection field.