The Filterscope: A Technical Guide & User’s Manual

Low-cost, remote, bandpass radiometers are a powerful spectroscopic tool used in high temperature plasmaphysics experiments throughout the world, particularly for fusion energy devices, i.e. those producing highlevels 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, Z_eff; B) scrape-o-layer (SOL) plasmatemperatures and densities; and C) plasma-wall interaction phenomenon. Over two decades ago, a versionof such a radiometer system, the Filterscope, was developed by scientists at ORNL. The Filterscope extendsthe 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 filterscopesystem. It gives an overview of the diagnostic philosophy and design as well as details on the implementationand operation of the complete system.