title: Versatile four-probe ac conductivity measurement system.
abstract: The design of a four-probe ac conductivity measurement system is described. The system is capable of making precision conductance measurements from 10(-8) to 10(-5) S at 20 to 200 Hz. Driven coaxial shields and a controlled current source are utilized to eliminate phase shift/attenuation errors, and make the measurement of conductances on a variety of materials a routine procedure requiring a minimum of operator intervention.
authors.affiliation: Department of Chemistry and Material Research Center, Northwestern University, Evanston, Illinois 60201, USA.
authors.forename: T E
authors.initials: TE
authors.lastname: Phillips
authors.forename: J R
authors.initials: JR
authors.lastname: Anderson
authors.forename: C J
authors.initials: CJ
authors.lastname: Schramm
authors.forename: B M
authors.initials: BM
authors.lastname: Hoffman