TOMOGRAPHIC AND SPECTROSCOPIC X-RAY DIAGNOSTIC DESIGN FOR THE TARA MAGNETIC MIRROR

THE TARA TANDEM MAGNETIC MIRROR AT M.I.T. WILL PLAY AN IMPORTANT ROLE IN THE MIRROR FUSION RESEARCH PROGRAM. IT WILL TEST THE EFFICACY OF A MAGNETIC CONFIGURATION WHICH IS DIFFERENT FROM THOSE OF OTHER LEADING MIRROR DEVICES (SUCH AS TMX-U AND MFTF-B), AND IT WILL BE USED FOR STUDYING BASIC PHYSICAL PROCESSES WHICH IT SHARES WITH OTHER TANDEM MIRRORS. IMPORTANT CHARACTERISTICS OF THE ELECTRON AND ION CONFINEMENT IN TARA (AND IN THE OTHER MACHINES) ARE DETERMINED BY ELECTROSTATIC POTENTIALS WHICH ARE CREATED OR STRONGLY AFFECTED BY SPECIAL POPULATIONS OF ELECTRONS THAT ARE HEATED BY ELECTRON CYCLOTRON RESONANCE HEATING. THE EFFECTIVENESS OF THESE POTENTIALS DEPENDS LARGELY ON THE SPATIAL DISTRIBUTION OF ECRH POWER DEPOSITION IN THE PLASMA AND ON THE ENERGY DISTRIBUTIONS OF THE HEATED ELECTRONS. THESE CHARACTERISTICS OF ECRH HAVE NOT BEEN STUDIED IN DETAIL ON ANY MIRROR MACHINE, IN SPITE OF THEIR IMPORTANCES, BECAUSE OF THE LACK OF APPROPRIATE DIAGNOSTIC INSTRUMENTS. WE PROPOSE TO DESIGN AND BUILD A SET OF X-RAY DIAGNOSTIC INSTRUMENTS WHICH WILL BE USED TO MONITOR AND STUDY THESE PROCESSES IN TARA. TOMOGRAPHIC X-RAY IMAGING (WHICH HAS NEVER BEFORE BEEN APPLIED TO MIRROR DIAGNOSTICS) WILL BE USED TO STUDY THE 2-DIMENSIONAL DISTRIBUTION OF ECRH ON RESOPANT HEATING SURFACES, AND MULTICHORD SPECTROSCOPIC MEASUREMENTS WILL BE USED TO MONITOR ENERGY DISTRIBUTIONS. DESIGN OF AN APPROPRIATE INSTRUMENT SET, AND PRELIMINARY MEASUREMENTS TO BE USED IN THAT DESIGN, WILL BE UNDERTAKEN IN PHASE I. THE INSTRUMENTS WILL BE FABRICATED AND USED IN A PHASE II PROGRAM.