Internal probe array for the measurement of radial electric field

A multipoint radial electric field probe, paired with a Langmuir triple probe has been operated on a RF sustained field reversed configuration. Langmuir probe measurements confirm the approximation that Te (r)∼ constant , allowing for simpler interpretation of the floating potential, and the probe array was implemented with nonemissive, floating probes. Due to the large antenna potentials (multi-kilovolts), the electric field probe was designed taking advantage of the development of inexpensive, multichannel, portable digital storage oscilloscopes. This also made it possible to operate the internal plasma diagnostic with a minimum of electrical design work and fewer calibration issues. The diagnostic was electrically isolated (floated) separate from experiment ground, and has been used to measure transient electric fields as large as 2.5 kV / m .