AN X-RAY BEAM DEFLECTOR FOR HIGH RESOLUTION SPECTROSCOPY OF FUSION PLASMAS

SMALL QUANTITIES OF KRYPTON WILL BE INJECTED INTO THE INTERNATIONAL THERMONUCLEAR EXPERIMENTAL REACTOR (ITER) AS A MEANS OF RADIATIVELY COOLING THE EDGE OF THE PLASMA IN ORDER TO PROTECT THE COMPONENTS EXPOSED TO THE PLASMA. THE KRYPTON WILL BE IONIZED TO THE HELIUM-LIKE STAGE UNDER THE CONDITIONS EXPECTED AT THE CORE OF THE ITER PLASMA. HIGH RESOLUTION X-RAY SPECTROSCOPY OF THE K LINES OF HELIUM-LIKE KRYPTON HAS BEEN SUGGESTED AS A MEANS OF MEASURING THE CENTRAL ION TEMPERATURE OF ITER. THIS PROJECT WILL CONSTRUCT AN X-RAY OPTICAL SYSTEM THAT WILL DEFLECT THE 13 KEV KRYPTON K X-RAYS TOWARD THE APERTURE OF A SHIELDED HIGH RESOLUTION X-RAY SPECTROMETER WHILE THE PATHS OF NEUTRONS, GAMMA RAYS, AND X-RAYS OF OTHER ENERGIES TRAVEL IN A STRAIGHT LINE TOWARD AN ABSORBER. THIS OPTICAL SYSTEM WILL IMPROVE THE SIGNAL TO NOISE RATIO OF THE HIGH RESOLUTION SPECTROMETER IN TWO WAYS. IT WILL KEEP BACKGROUND RADIATION AWAY FROM THE POSITION SENSITIVE X-RAY DETECTOR, AND IT WILL ELIMINATE 6.5 KEV CONTINUUM X-RAYS WHICH WOULD OTHERWISE BE DIFFRACTED IN FIRST ORDER TO OVERLAP THE KRYPTON X-RAY LINES. DURING PHASE I, THE REQUIREMENTS FOR THE KRYPTON X-RAY BEAM DEFLECTOR, WILL BE ESTABLISHED, A PRELIMINARY DESIGN CONCEPT FOR THE BEAM DEFLECTOR WILL BE DEVELOPED AND THE X-RAY OPTICAL ELEMENTS WILL BE SPECIFIED AND MODELED IN ORDER TO ESTIMATE THE IMPROVEMENT TO BE EXPECTED WITH THIS SYSTEM. THIS INFORMATION WILL BE AVAILABLE IN TIME FOR CRITICAL DESIGN DECISIONS CONCERNING ITER DIAGNOSTICS. IN PHASE II, WE WILL BUILD AN ENGINEERING VERIFICATION PROTOTYPE BEAM DEFLECTION SYSTEM FOR INSTALLATION AT THE TOKAMAK PHYSICS EXPERIMENT (TPX).