An electrically insulating plasma reactor with a Faraday shielded inductive source antenna permits direct control of the dc plasma potential of the discharge. This control may be used to provide a tailored ion energy distribution at a substrate of fixed potential or to fix the plasma potential at a chosen value. With a reactor constructed from Pyrex tubing and a Faraday shielded inductive source coil, all that is required to control the plasma potential is a small electrostatic probe in contact with the plasma. By applying a stairstep potential to the probe, it is possible to create an ion energy distribution possessing virtually any desired shape. Insulating reactors could provide a novel way to control ion production and ion energy separately without the need for direct substrate biasing. They may also provide a way to maintain a consistent plasma potential in a processing reactor in situations where the reactor walls are easily contaminated by the process. ©1997 American Institute of Physics.