X-ray imaging arrays for impurity transport studies on the Texas Experimental Tokamak

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Abstract
Three multichannel soft x‐ray imaging arrays are used for impurity transport studies on the Texas Experimental Tokamak. The entire system has a total of 92 broadband x‐ray detectors that view the plasma at the same toroidal location from three different poloidal angles: Array A is a 40‐channel vertically viewing set of silicon surface barrier diodes (SBDs); array B is a 40‐channel horizontally viewing set of SBDs; and array C is a 12‐channel set of p‐intrinsic‐n (p‐i‐n) detectors viewing the plasma from 45° above the horizontal plane. Array B is absolutely calibrated; array A is relatively calibrated in situ; and array C is cross‐calibrated relative to array B. In this article we describe the primary components of the system: (1) the specific x‐ray diodes used for the arrays and their spectral sensitivities; (2) the corresponding electronics necessary for data acquisition; and (3) the vacuum system for the arrays. Furthermore, we describe a novel krypton edge absorption filter which discriminates between the resonance line radiation of He‐like and H‐like aluminum injected into TEXT plasmas.