X-rays to pierce plasma secrets
ITER Technical Responsible Officer Robin Barnsley presents the technical details of the Edge Imaging X-ray Spectrometer. Also present: Dhiraj Bora, head of the Directorate for CODAC, Heating & Diagnostics; Mike Walsh, Diagnostic Division head; and Dilshad Sulaiman, a young Indian Domestic Agency staff member presently working at ITER.
A hot plasma is a bit like a star: it gives out light all across the electromagnetic spectrum, from radio waves all the way through X-rays to gamma rays.
When astrophysicists want to know what happens inside a star—how hot it is, what elements it is composed of—they use a spectrometer. A fusion physicist does exactly the same with a fusion plasma.
The light spectrum carries a considerable amount of information. Aim the proper spectrometer toward a region of the plasma and it will tell you how many impurities are present, how the temperature varies, and how fast the tenuous gas rotates.
The Edge Imaging X-ray Spectrometer that the Indian Domestic Agency will procure for ITER will be a valuable diagnostic tool. Last Wednesday, 28 March, the Procurement Arrangement documents were signed by Director-General Motojima; this Monday the documents will be countersigned by ITER-India Project Director Shishir Deshpande.
The Edge Imaging X-ray Spectrometer is one of three X-ray subsystems that will look at different regions of the ITER plasma in order to provide accurate measurements of their behaviour and performance. It is a vacuum-coupled, multi-channel device that sits behind a port plug and will have a very narrow, direct line of sight to the upper edge region of the D-shaped plasma.
This first diagnostics Procurement Arrangement signed with India is an exemplary one. The whole process was a close collaboration between ITER and the Indian Domestic Agency which sent several staff members for long periods to Cadarache, creating strong bonds between the institutions. "Working with the ITER team has been a great pleasure," says Sanjeev Varshney, technical responsible officer at the Indian Domestic Agency.
Dhiraj Bora, head of the Directorate for CODAC, Heating & Diagnostics, was present on Wednesday along with Diagnostics Division Head Mike Walsh, ITER Technical Responsible Officer Robin Barnsley, and one of the young Indian Domestic Agency staff members presently working at ITER, Dilshad Sulaiman.
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