KSTAR, a nuclear fusion reactor which is also called Korea’s “artificial sun,” has successfully achieved a plasma core ion fusion temperature of 100 million degrees, becoming the first tokamak fusion device to achieve the milestone.
KSTAR is short for Korea Superconducting Tokamak Advanced Research. It is a magnetic fusion device intended to study magnetic fusion energy, which is considered a next-generation energy source.
The National Fusion Research Institute (NFRI) announced on Jan. 13 that KSTAR maintained the plasma core temperature of 100 million degrees (9 keV) for 1.5 seconds in an experiment conducted from August to December last year.
A plasma ion temperature of 100 million degrees is seven times higher than the temperature of the core of the sun (15 million degrees). The temperature is regarded as the most critical operating condition of a nuclear fusion reactor.
A fusion power plant puts hydrogen gas in a plasma state at a temperature 10 times higher than the temperature inside the sun and produces a large amount of energy during the fusion process of deuterium and tritium into helium. This process does not produce radiation.
To produce energy through nuclear fusion, high-density deuterium and tritium ions must be stably held at a high temperature for a long time and be induced to spontaneous fusion without external auxiliary heating. A technology to convert energy generated by nuclear fusion into heat energy is also necessary. "The optimal temperature at which fusion between deuterium and tritium occurs is 150 million degrees. Nuclear fusion energy has no carbon dioxide emissions, and fuel can be supplied indefinitely from seawater,"said Yoo Suk-jae, director of the NFRI.
Previously, the Institute of Plasma Physics of the Chinese Academy of Sciences announced that it succeeded in making an artificial sun that produces hundred million degrees of heat using EAST, a thermonuclear experimental reactor.
But the NFRI says that the Chinese reactor raised the temperature of the electron, not ion. In July 2017, China succeeded in maintaining the ultra-high-temperature plasma state for 101.2 seconds. The Chinese Institute of Plasma Physics said at the time, "We are close to meeting various physical conditions for stable nuclear fusion operation, and we have established an important technological basis for development of clean nuclear energy for humanity." China aims to build a thermonuclear power plant in 2035.
However, the NFRI argues that KSTAR's plasma ion temperature of 100 million degrees is technically superior to China's since it increases the ion temperature by effectively heating the center of the plasma using the neutron particle beam heater (NBI-1). In 2017, KSTAR has succeeded in high-performance plasma mode (H-mode) operation in which plasma with an electron temperature of 70 million degrees was maintained for about 90 seconds.
KSTAR’s goal for this year is to use NBI-2 to maintain super-high-temperature plasma over 100 million degrees for more than 10 seconds. This will allow Korea to lead the high-performance plasma experiment at the international thermonuclear experimental reactor (ITER), which is under construction in Kadaracheu, France. Currently, seven countries, including China, the United States, South Korea, Japan, Russia, the European Union (EU) and India, are pushing to complete the ITER by 2025. ITER is working on enabling experimental verification of the maintenance of voluntary nuclear fusion at 150 million degrees without supplementary heating starting from 2035.
The NFRI will hold the KSTAR Conference 2019, an international thermonuclear conference, along with the 10th anniversary celebration of KSTAR operation at COEX from Jan. 20 to 22. "There are many technical difficulties to overcome in order to establish a thermonuclear power plant," said Yoon Si-woo, director of the KSTAR Research Center. "The good news is that research has been accelerated due to the Fourth Industrial Revolution technologies, such as artificial intelligence and virtual reality (VR). The United States, Europe, and Japan have begun their nuclear fusion research earlier than Korea, but latecomers Korea and China have provided breakthroughs."
KSTAR’s latest achievement has brought Korea one step closer to achieving the goal of constructing a nuclear fusion power plant in the 2050s.