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Sjak Jansen - Internship at EAST in China

Reported by Sjak Jansen. Powered by FuseNet

In the spring of 2016, I went to Hefei in China for an internship of 10 weeks at the EAST tokamak. During this period I worked on X-ray crystal spectroscopy under supervision of Prof. Dr. Bo Lyu and Prof. Dr. Roger Jaspers. The Experimental Advanced Superconducting Tokamak (EAST) is one of two large tokamaks in China.

Using X-ray Crystal Spectroscopy to measure ion temperatures

For future tokamak experiments, like ITER and DEMO, the diagnostic tools have to improve. The ion temperature, currently measured with charge exchange recombination spectroscopy (CXRS), faces the engineering challenge of developing a neutral beam able to penetrate the core. One alternative that is investigated at EAST in Hefei, is to measure the ion temperature by measuring the x-ray spectrum (XCS) of injected argon particles. The current installed XCS is able to measure the spectra of Helium-like (16+) and Hydrogen-like (17+) argon. The hydrogen-like argon measurement is relatively new and under development.

For increased electron temperatures the relative abundance of H-like Argon increases while the population of He-like Argon decreases. Therefore by measuring the radiation of H-like Argon, information about the ion temperature can be extracted. In high temperature plasmas, the intensity by the He-like Argon component will decrease while the its counterpart from the H-like Argon component will increase. This development should improve the ion temperature measurement.

During my research I worked on a method for extracting the ion temperature from the measured line radiation with a XCS setup. In order to improve the accuracy of the ion temperature measurement, I investigated whether the measured spectrum is better fitted with a Gaussian or a so-called Voigt shape. I also worked on improving and justifying the ground level background intensity that is subtracted, before the Gaussian shape is fitted.

Enjoying Hefei: from local dumplings to amazing parties

During my research, I met many internationals who were staying in Hefei. My stay included a variety of activities and experiences: from making homemade dumplings, a local speciality to amazing parties in the Hefei nightlife. The hard work of my research was paired nicely with a lot of fun outside the workplace. I had the opportunity to meet many great scientists and fellow expats.

I would like to thank all of my friends and colleagues who made my stay so memorable. Especially, I would like to thank my supervisor for his help with the accomodation arrangement as well as his valuable advice for my project. Furthermore I would like thank my office mates for helping me to find my way around Hefei.

Finally I would like to thank FuseNet for the financial support, without which I would not have been able to go abroad for my internship and experience a different research environment and culture.