Fast electron temperature measurements using a "multicolor" optical soft x-ray array

• Published in: Journal of applied physics Vol. 102; no. 7; pp. 073304 - 073304-7
• Main Authors: Delgado-Aparicio, L. F., Stutman, D., Tritz, K., Finkenthal, M., Bell, R., Hosea, J., Kaita, R., LeBlanc, B., Roquemore, L., Wilson, J. R.
• Format: Journal Article
• Language: English
• Published: United States American Institute of Physics 01.10.2007
• Subjects: 70 PLASMA PHYSICS AND FUSION TECHNOLOGY; BERYLLIUM; BRIGHTNESS; ELECTRON TEMPERATURE; EMISSIVITY; FOILS; ION TEMPERATURE; PHOSPHORS; PLASMA; PLASMA CONFINEMENT; PLASMA DIAGNOSTICS; PLASMA SIMULATION; SOFT X RADIATION; SPHERICAL CONFIGURATION; THICKNESS
• ISSN: 0021-8979; 1089-7550
• DOI: 10.1063/1.2786034

A fast ( ⩽ 0.1 ms ) and compact "multicolor" scintillator-based optical soft x-ray (OSXR) array has been developed for time- and space-resolved measurements of the electron temperature [ T e ( R , t ) ] profiles in magnetically confined fusion plasmas. The 48-channel tangential multicolor OSXR prototype was tested on the National Spherical Torus Experiment. Each sight line views the same plasma volume at the midplane ( 0 ⩽ r ∕ a ⩽ 1 ) , in three distinct energy ranges determined by beryllium foils with different thicknesses. A tangential view of the toroidally (circular) symmetric plasma allows an Abel inversion of the line-integrated SXR brightness to obtain the x-ray emissivity profiles which are then used to constrain the reconstruction of the fast T e ( R , t ) . The first assessment of the electron temperature is obtained by modeling the slope of the continuum radiation with the ideal double-foil method using both the line-integrated intensity measurements as well as the inverted SXR emissivity profiles.