National Institute for Fusion Science

During 2013, in the Large Helical Device (LHD) we collected 891.6 gigabytes of diagnostic data per experiment, an average which became a new world record for the amount of data collected in this field. This figure is a record that approaches the approximately one terabyte of data that will be collected from each experiment to be conducted at the International Thermonuclear Experimental Reactor (ITER), which is under construction in southern France, upon its opening in 2020. (One terabyte is 1,000 gigabytes, or a quantity of information that is equal to approximately 230 movies or to newspapers stacked to approximately 2,000 meters.) At present, among fusion experiment devices in operation around the world, it is well known that the LHD is at the forefront regarding data collection. In storing the important “big data” born of the LHD experiments, cutting edge information technologies that have been produced in Japan are being used. Here, we will introduce an example from the development of the LHD’s data collection technology that has had great influence upon the direction of development within the information technology industry.

Among devices that preserve a variety of data are devices with semiconductor flash memories such as magnetic discs, magnetic tape, and USB memory. Further, there are DVDs, Blu-ray discs, and other optical discs. Among these discs, for the long-term preservation of invaluable data optical discs, in particular, Blu-ray discs that combine high reliability and long life are considered most appropriate. In the LHD experiments, too, we are using the Blu-ray disc’s library device for the long-term preservation and use of data. The library device is an automatic device that selects the optical disc entered into each of the approximately 1,000 slots and removes that disc by the robot’s arm, and then conveys the information to the reading/writing drive. This is also called a “jukebox,” an object that older people know well, due to its function and movement. Optical disc technology is a field in which Japanese companies are leading the world, with Sony and Matsushita’s “Blu-ray Disc” and Toshiba’s “HD-DVD” competing for supremacy. Some readers may recall that the Blu-ray disc emerged victorious.

When compared to magnetic discs and magnetic tape, the Blu-ray disc, which was appropriate for long-term preservation, had the weaknesses of insufficient memory capacity and of being slow in reading speed and writing speed. Just two years ago, even using eight Blu-ray discs simultaneously recording data from one day of experiments took more the 24 hours. Improvement in long-term preservation and archiving of “big data,” about which reports have appeared on television news and in newspapers, could not be overlooked. As a result, two Japanese Blu-ray disc makers have reduced 12 Blu-ray discs to one cartridge, and each company announced in 2012-2013 the introduction of products that have been improved by one digit in quantity and speed, and improved also in efficiency.

In response, the LHD, which at that time already was a big user of Blu-ray discs, rather than make each maker’s technology compete, directly informed each maker that it would be desirable for the Blu-ray discs’ specifications to be broader and for there to be standards that could be relied upon for long-term development. At the same time, by publishing articles in industry magazines the National Institute for Fusion Science appealed to the entire optical disc industry in Japan. As a result, two Japanese companies agreed to introduce unified specifications for the next-generation Blu-ray disc. That was announced in March, 2014.

Fusion research is a large-scale research project sometimes called “big physics.” Leading-edge technologies in numerous fields are being utilized, and, as introduced here, this extends an important influence also over the future development of the information technology industry in Japan. One of those influences may perhaps be said to be the ripple effect from one field to another of technology born from developments in fusion research.