Ion source repeller shield comprising a labyrinth seal

An ion source, comprising:

• an arc chamber having a body defining an interior region of the arc chamber;
• a liner operably coupled to the body of the arc chamber, wherein the liner is unitary and generally encloses the interior region of the arc chamber, the liner having a first surface and a second surface, wherein the second surface is recessed from the first surface, therein defining a liner recess region, the liner further having a hole defined therethrough in the liner recess region, wherein the hole has a first diameter, and wherein the liner further comprises a liner lip extending upwardly from the second surface toward the first surface, wherein the liner lip surrounds the hole and has a second diameter associated therewith;
• and
• an electrode having a shaft and a head, wherein the shaft has a third diameter that is less than the first diameter, wherein the shaft passes through the body and the hole in the liner and is electrically isolated from the liner by an annular gap, wherein the head has a fourth diameter and comprises a third surface having an electrode lip extending downwardly from the third surface toward the second surface, wherein the electrode lip has a fifth diameter associated therewith, wherein the fifth diameter is between the second diameter and the fourth diameter, wherein a spacing between the liner lip and electrode lip generally defines a labyrinth seal and generally prevents contaminants from entering the annular gap, and wherein the shaft further comprises an annular groove defined therein having a sixth diameter, wherein the sixth diameter is less than the third diameter;
• and
• a boron nitride seal, wherein the boron nitride seal engages the annular groove, therein sealing the interior region of the arc chamber from an exterior region thereof.

An apparatus for preventing a leakage of gases from an interior region of a body of an arc chamber to an exterior region of the body of the arc chamber, the apparatus comprising:

• a liner having a first surface and a second surface, wherein the second surface is recessed from the first surface, therein defining a liner recess region, wherein the liner is unitary and generally encloses the interior region of the arc chamber, the liner further having a hole defined therethrough in the liner recess region, wherein the hole has a first diameter, and wherein the liner further comprises a liner lip extending upwardly from the second surface toward the first surface, wherein the liner lip surrounds the hole and has a second diameter associated therewith;
• and
• an electrode having a shaft and a head, wherein the shaft has a third diameter that is less than the first diameter, wherein the shaft passes through the body and the hole in the liner and is electrically isolated from the liner by an annular gap, wherein the head has a fourth diameter and comprises a third surface having an electrode lip extending downwardly from the third surface toward the second surface, wherein the electrode lip has a fifth diameter associated therewith, wherein the fifth diameter is between the second diameter and the fourth diameter, wherein a spacing between the liner lip and electrode lip is approximately equal to the annular gap between the shaft and the liner and generally defines a labyrinth seal and generally prevents contaminants from entering the annular gap, and wherein the shaft further comprises an annular groove defined therein having a sixth diameter, wherein the sixth diameter is less than the third diameter;
• and
• a boron nitride seal, wherein the boron nitride seal engages the annular groove, therein sealing the interior region of the arc chamber from the exterior region thereof, wherein the labyrinth seal generally protects a sealing surface of the shaft from corrosive gases associated with the interior region of the arc chamber by reducing conductance of the corrosive gases into an area associated with the boron nitride seal.