Ion sensitive probe measurement in the linear plasma device PSI-2

The suitability of an ion sensitive probe (ISP) with respect to ion temperature (Ti) measurements has been tested in the linear plasma generator in PSI-2. Current–voltage (I–V) characteristics were recorded as a function of two key parameters: shielding height (h) and potential differences between inner and outer electrodes (VB). It could be experimentally confirmed that the current within the electron saturation region is reduced with increasing h. Furthermore, the I–V characteristics change drastically when VB is varied. Radial profiles of the plasma parameters including plasma and floating potentials could be taken. Whereas the Ti values determined by ISP in the plasma core region agree fairly with those obtained by using a local optical probe, severe interpretation difficulties occurred for the outer regions.