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December 27, 2013
The Seventeenth Cycle of Experiments Has Ended: The Performance of Plasma Has Improved Further

The seventeenth cycle of experiments using the Large Helical Device (LHD) concluded on December 25, 2013. This year’s cycle of experiments, the seventeenth since the beginning of experiments in 1998, began on October 2, and there were 7,300 plasma discharges over 52 days. Conducting joint research with many researchers from universities in Japan and abroad, during this period we moved forward in various experiments and research, and we concluded the plasma experiments without occurrence. During the experiment period, on October 30 the 120,000th plasma discharge since 1998 was conducted. Conducting the 120,000th plasma discharge in the sixteenth year of experiments is an unmatched speed for a large device such as the LHD. Because of this pace we are able to introduce various research results one after another. The high operational reliability of the superconducting coils system has made this possible.

In this year’s experiments, too, numerous results were obtained, and together with the LHD’s enhancement of plasma performance we succeeded in greatly advancing our research. We achieved high ion temperature that exceeded the 85,000,000 degrees Celsius recorded last year, and the special qualities of that high ion-temperature plasma were investigated. Further, we greatly improved our world record for consecutive heat inputs of energy that the LHD had achieved in the past. And we succeeded in steadily maintaining high performance plasma for more than 45 minutes. Research aimed at achieving future fusion energy advanced. Parallel with those achievements, we investigated in detail the behaviors of the boundaries of plasma as it is floating in space while confined in the magnetic field container. We energetically conducted physics experiments in order to clarify the complicated phenomena that occur together with enhancing the performance of plasma. And we were able to deepen further our scientific understanding for the design of the future fusion power plant. Regarding this year’s research results, from now we will advance our analysis of the data and introduce the findings later. Please look forward to that report.

Accompanying the completion of the plasma experiments, from December 26, 2013, we are conducting operations that raise the temperature of the superconducting magnet from -270 degrees Celsius, to which it had been cooled, to room temperature. After the end of year-new year break, over a period of four weeks we will gradually raise the temperature to room temperature. Then from the last third of January, when the raising of the temperature will conclude, we plan to begin maintenance checks. As visits to observe the LHD are restricted during the plasma experiment period, we encourage people nearby to visit until the eighteenth plasma experiment cycle begins in the fall of 2014.