First results of reverse field experiment vertical time-of-flight

The charge exchange neutral particle outfluxes and ion temperature are important quantities for the determination of the power balances and the plasma’s energetic content; therefore they constitute a long term issue of reversed field pinch research. In order to improve the experimental knowledge of these plasma quantities, in the reversed field experiment a vertical time-of-flight (TOF) neutral particle analyzer (NPA) has been recently installed. It sees the plasma along a vertical chord, whose impact parameter is about half radius, and it is meant to complement the other two NPAs, which are installed on the equatorial plane. In this article, the new vertical TOF is reported, with particular attention to its more original components. An “in situ” method to calibrate the electron multiplier gain absolutely is described in detail. The first measurements of the ion temperature are reported, showing the reliable operation of the system and the acceptable signal-to-noise ratio obtained up to now. The results are also compared with the measurements of the horizontal NPAs mainly in the experimental regime of high plasma density. Possible improvements of the new diagnostic and its use in combination with a neutral particle beam are also briefly described and discussed.