THE DEVELOPMENT OF SHIELDED X-RAY PLASMA DIAGNOSTIC DETECTORS FOR HIGH RADIATION BACKGROUNDS

X-RAY DIAGNOSTIC INSTRUMENTS ARE CONVENIENT FOR DEFINING SUCH PLASMA PARAMETERS AS THE ELECTRON TEMPERATURE, ION TEMPERATURE, DENSITY, AND IMPURITY CONCENTRATION AS A FUNCTION OF POSITION WITHIN A MAGNETICALLY CONFINED PLASMA. THERE IS, HOWEVER, A NEED TO PROTECT THE INSTRUMENT FROM THE ADVERSE EFFECTS OF THE PLASMA UNDER STUDY. SOME X-RAY DETECTORS AND DISPERSING ELEMENTS CAN BE DAMAGED OR DESTROYED BY THE RADIATION ENVIRONMENT ASSOCIATED WITH FUSION EXPERIMENTS. IN ADDITION, SENSITIVE DETECTORS CAN BE SUBJECT TO VERY HIGH BACKGROUND COUNTING RATES. MANY OF THE STANDARD X-RAY PLASMA DIAGNOSTIC INSTRUMENTS ARE UNABLE TO WITHSTAND THE RADIATION BACKGROUND OF TFTR (THE TOKAMAK FUSION TEST REACTOR), CIT (THE COMPACT IGNITION TOKAMAK), OR FUTURE FUSION REACTORS. THE SOLUTION IS TO DESIGN INSTRUMENTS IN WHICH THE SENSITIVE COMPONENTS ARE SHIELDED FROM THE FUSION ENVIRONMENT WHILE THE X-RAY FLUX IS CONVEYED TO THEM. THIS CAN BE ACCOMPLISHED THROUGH THE USE OF X-RAY-TRANSMITTING FIBER OPTICS. X-RAY FIBER OPTICS ARE BROADBAND, COMPACT, AND HIGHLY DIRECTIONAL. IT IS THEREFORE POSSIBLE TO DESIGN DETECTORS THAT ARE INSENSITIVE TO THE HIGH RADIATION BACKGROUND. TO PROVE THE CONCEPT, THIS PROJECT WILL DEVELOP A RADIATION-RESISTANT DETECTOR ASSEMBLY FOR THE SOXMOS (SOFT X-RAY MONOCHROMATOR-SPECTROMETER) AT TFTR.