ALPHA PARTICLE DIAGNOSTICS USING MILLIMETER SCATTERING TECHNIQUES

A FAST, RELIABLE, QUANTITATIVE ALPHA PARTICLE DIAGNOSTIC MEASURING SYSTEM IS AN IMPORTANT COMPONENT IN BOTH THE NEAR TERM AND FUTURE MAGNETIC FUSION PROGRAM. BURNING PLASMA EXPERIMENTS IN THE TOKAMAK FUSION TEST REACTOR AND OTHER EXISTING TOKAMAKS, AND IGNITED PLASMA CONDITIONS IN THE COMPACT IGNITION TOKAMAK, ARE EXPECTED TO ESTABLISH THE ALPHA PARTICLE PHYSICS BASIS NEEDED FOR THE FUSION ENERGY DEVELOPMENT PROGRAM. FOR HOMOGENEOUS MAGNETOPLASMAS, RF SCATTERING OFF ELECTRON FLUCTUATIONS CAN BE USED TO DETERMINE ALL OF THE CHARACTERISTICS OF THE ALPHA PARTICLE DISTRIBUTION FUNCTION NEEDED TO EVALUATE THE IMPORTANT ALPHA-INDUCED MODIFICATIONS OF TOKAMAK PERFORMANCE. IN ADDITION, THIS SAME DIAGNOSTIC SYSTEM CAN BE USED TO DETERMINE OTHER KEY PLASMA AND FIELD DATA, AND, IN PRINCIPLE, CAN DO ALL OF THIS IN A DIRECT INTERPRETIVE WAY WITHOUT PERTURBING THE PLASMA. THE PHASE I RESEARCH PROGRAMWILL DETERMINE THE FULL ELECTROMAGNETIC ELECTRON FLUCTUATION SPECTRAL FUNCTION AND EVALUATE THE SCATTERING STRENGTH IN IMPORTANT PARAMETER REGIONS FOR ALPHA PARTICLE DETECTION. THESE RESULTS WILL ALSO BE ASSESSES FOR SENSITIVITY TO INHOMOGENEITIES BECAUSE SUCH REAL SYSTEM EFFECTS CAN CRITICALLY MODIFY THE QUANTITATIVE AND INTERPRETIVE NATURE OF THIS DIAGNOSTIC SCHEME. PLASMA AND FIELD INHOMOGENEITIES, FINITE DETECTOR DISTANCE AND RESOLUTION, INCIDENT AND SCATTERING WAVE REFRACTION, AND BACK-SCATTER OFF WALLS CAN PRODUCE STRONG COMPETING SCATTERED SIGNAL EFFECTS. MANY OF THESE EFFECTS CAN BE MINIMIZED, IF THEY ARE IDENTIFIED, THROUGH DIAGNOSTIC SYSTEM DESIGN. THE OTHERS CAN BE EVALUATED USING STANDARD RAY-TRACING CODES. THE EXPECTED PRODUCT OF THE SUCCESSFUL COMPLETION OF THIS ENTIRE RESEARCH PROGRAM WILL BE A SET OF NECESSARY DESIGN CHARACTERISTICS TO MINIMIZE DELETERIOUS FINITE SYSTEM EFFECTS AND A CODE THAT RAPIDLY EVALUATES THE INHOMOGENEOUS FEATURES AND QUANTITATIVELY INTERPRETS THE SCATTERING DATA IN TERMS OF ALPHA PARTICLE CHARACTERISTICS.