The Filterscope: A Technical Guide & User’s Manual

Abstract

Low-cost, remote, bandpass radiometers are a powerful spectroscopic tool used in high temperature plasma physics experiments throughout the world, particularly for fusion energy devices, i.e. those producing high levels of radiation. Examples of the measurements made using these types of radiometers are for: A) Core parameters such as the eective ion charge of the plasma, Ze f f ; B) scrape-o-layer (SOL) plasma temperatures and densities; and C) plasma-wall interaction phenomenon. Over two decades ago, a version of such a radiometer system, the Filterscope, was developed by scientists at ORNL. The Filterscope extends the band-pass radiometer technique to make the instrument extremely modular/expandable, robust, and very-fast (with digitization up to 1 MHz) and has been deployed on fusion devices throughout the world. Additionally, a fast band-pass radiometer has other potential uses beyond fusion plasma diagnosis, e.g. LIDAR, X-ray medical diagnostics, radiation monitoring, and solar radiation measurement. This technical report is intended as a user’s guide and a reference manual for the use of the ORNL filterscope system. It gives an overview of the diagnostic philosophy and design as well as details on the implementation and operation of the complete system.