An apparatus may include a main chamber, an entrance tunnel, having an entrance axis extending into the main chamber, and an exit tunnel, connected to the main chamber and defining an exit axis, wherein the entrance tunnel and the exit tunnel define a beam bend of less than 25 degrees therebetween. The apparatus may include an electrode assembly, disposed in the main chamber, on a lower side of the exit tunnel; and a catch assembly, disposed within the main chamber, in a line of sight from an exterior aperture of the exit tunnel.