9
Neutralizer
: An electron source downstream from the ion source
For DC sources, the neutralizer can be a hot filament, hollow cathode, or plasma bridge type. A
plasma bridge neutralizer (PBN) is where a hot filament is placed in a smaller discharge chamber
through which an inert process gas is supplied. For RF sources, the neutralizer can be either a PBN
or RF type. The RF neutralizer (RFN) consists of a small discharge chamber with an RF coil. The
RFN utilizes a collector and keeper to emit electrons.
The purpose of the neutralizer is to emit electrons into the environment downstream from the ion
beam source. The emitted electrons provide a charge balance for the ions leaving the source.
Typically, more electrons are emitted from the neutralizer than ions from the source. This is done
to minimize and/or eliminate the space or surface charging that may occur. In most situations,
electrons from the neutralizer do not directly combine with the ions in the beam to form high
energy neutrals.