A variety of diagnostics have been fielded in different plasma sources to provide new information about the large area plasma processing system (LAPPS) at NRL. Specifically, a high resolution digital Langmuir probe system and ion flux/energy diagnostics have been employed in pulsed and dc electron beam produced plasmas as well as in an inductively coupled source as a baseline experiment. rf induced dc bias, ion flux, electron and ion temperature, and plasma potential in the proximity of rf powered electrodes placed into these plasmas were measured. It is found that the LAPPS plasma channel is essentially unaffected by the presence of the rf voltage, with the net ion flux unchanging in the presence of rf. These findings are consistent with earlier theoretical models of LAPPS [Manheimer et at.. Plasma Sources Sci. Technol. 9. 370 (2000)].