High resolution soft x-ray tomography in the Madison Symmetric Torus

We present in this article the description of the upgraded soft x-ray tomographic diagnostic which has been installed in the Madison symmetric torus (MST) reversed field pinch. The previous diagnostic has been extended with two manipulators, for a total of three moveable probes and a fixed one. The line integrated emissivity (brightness) will be measured with arrays of photodiodes and the total number of channels has been increased from 24 to 74. The electronic layout has also been upgraded, and a type of custom made current-to-voltage amplifier has been developed. The diagnostic will be used to continue and extend the magnetohydrodynamics analysis of the MST plasma. The imaging of rotating coherent structures (one or, as recently showed, two) which appear during quasisingle helicity or pulsed poloidal current drive experiments will be performed in more detail. The photocameras can be easily extracted, modified, and inserted again, allowing applications and utilizations of the diagnostic. © 2004 American Institute of Physics.