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Ray Chandra - Internship at KSTAR

Internship at KSTAR - Daejeon, South Korea
Reported by Ray Chandra. Powered by FuseNet

My name is Ray Chandra and I have been doing an internship project at Korea Superconducting Tokamak Advanced Research (KSTAR) in Daejeon, South Korea, which started in May and lasted until the end of July 2016. It was my first time visiting South Korea, but it has certainly been a wonderful experience. South Korea has its distinct culture with lots of interesting customs and places. The people are really friendly and the food is very nice. In addition, beautiful sceneries can be seen across the country and, as such, I had no worries about what I wanted to do in the weekends.

International KSTAR

KSTAR is a tokamak under the management of the National Fusion Research Institute (NFRI). Because of the colaborations with other institutes, the atmosphere at KSTAR is very international. Although local courtesy among South Koreans are common, fusion science and research are of utmost importance at KSTAR and, as such, internationals are welcomed in a way that they do not feel like strangers.

OFIT: optical detection of the plasma boundary

The main topic of my project was the implementation and verification of OFIT, which is a method to construct the plasma boundary. Using information from fast CCD cameras, the plasma position and shape could be obtained by looking at the maximum intensity of the pixels in the CCD-image, since most of the plasma radiation is emitted at the plasma edge. Transformation, interpolation and extrapolation were needed to construct a full plasma boundary from the set of detected pixels. Some machine-specific adjustments were needed for the method to work at KSTAR, since it had been developed to work on tokamaks in general. Also, some additional functionality were added to cater its implementation.

 

Verification of this method could be beneficial for plasma control

The boundary constructed by OFIT was then verified by comparing it with EFIT, an analysis tool that also constructs the boundary based on magnetic data. This verificiation has been done for different plasma regimes, including H-mode, L-mode, and limiter mode. Additional diagnostics, such as Beam Emission Spectroscopy and infrared cameras, have also been used to verify OFIT. Results of these comparison between different methods showed that OFIT works well, but only in diverted L-mode regimes. For OFIT to work well in different regimes, further improvements are necessary.

Since plasma control is crucial in fusion to compensate for plasma instabilities, as well as to protect machine components from very high temperatures, the development of OFIT for different plasma regimes could be very beneficial, since it can provide us with a real-time diagnostic for control purposes.

The complexity of fusion research

In addition to the work on my project, my internship has also been a great opportunity for me to experience working in a large international research facility, which was especially emphasised by the fact that KSTAR was running its research campaign, during my time in South Korea. I was shown how complex fusion research is and that there are still plenty of problems that need to be solved, but it was encouraging to see so many people working together to solve these problems, and ultimately, the energy problem. Thanks to my supervisor, Cheonho Bae, and some of my new Korean friends, I was able to work at KSTAR in relative ease. Furthermore, I would also like to thank FuseNet for supporting me during my internship.