Overview of the diagnostic suite for the Proto-Lite experiment.

Oak Ridge National Laboratory (ORNL) has been developing RF-driven, linear plasma devices for plasma-material interaction (PMI) studies. The physics basis for the Material Plasma Exposure eXperiment (MPEX), under construction at ORNL, was established through experimental measurements on the Proto-MPEX device. The Proto-MPEX device has recently been reconfigured as the "Proto-Lite" platform, with the removal of auxiliary electron and ion heating capabilities and the reduction of the number of magnet coils from 13 to 8. Proto-Lite is a risk-reduction platform for MPEX, where helicon wave RF-technologies can be tested, plasma scenarios developed, new workforce members trained, diagnostic systems explored, and control architectures vetted, in addition to short-pulse PMI target exposures. The diagnostic suite for Proto-Lite largely consists of systems that were ported from Proto-MPEX or that are being readied for deployment on MPEX. The current Proto-Lite diagnostic set includes (typical achieved range; data rate): double Langmuir probes (Te ∼ 1-20 eV, ne ∼ 1018-1020 m-3; 1 kHz), infrared camera imaging (T ∼ 20-150 °C; 50 Hz full frame), filtered visible camera imaging (1-18 kfps), neutral pressure gauges (P ∼ 10-4-10-2 Torr; 100 Hz), residual gas mass spectroscopy (1-100 amu), survey (400-900 nm; 1 Hz), and high-resolution optical emission spectroscopy (200 Hz). Plasma exposed samples are removed via a vacuum load-lock for ex situ analysis. This paper will give an overview of experimental measurements from Proto-Lite diagnostic systems and describe how those systems are contributing to risk-reduction research for MPEX.